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Posted by: deglr6328 Nov 20 2005, 06:49 AM

What is going on with SETI@home? I have in the past, (like many of the other users of this board I suspect!) run the SETI@home screensaver on my computer. I ran it for about 4 years and then uninstalled it. Not because I was fed up with not having an ET directly send to me personally a big "HELLO THERE" message, but rather because I saw little in the way of actual science being done with the SETI results we volunteers were all producing and because there seemed to be no plan for any kind of endpoint of the project in the future.

I recall seeing in a 2000 edition of Scientific American a plot of the already searched parameter space by SETI@home and it looked like most of our galaxy was searched and found empty obviously, of "type I civilizations" and higher. (ah. http://%27http://stuff.mit.edu/people/etekle/Articles/0700crawfordbox5.html%27) Now, its been 6 years since then and we've since viewed ~97% of the observable sky from Arecibo at least once since the start of the project (~86% at least twice). Why are there no papers published on this result? It IS a significant result even if its negative one. Were there SETI papers published that I've just not seen? The SETI and SETI@home web sites are of very little help when looking for actual peer reviewed published papers that the projects have produced.

Posted by: Richard Trigaux Nov 20 2005, 10:06 AM

I think this is an interesting topic, and that it fully deserves its place here as a science/technology concern, if we left besides any childish a priori in the style "life on other planets must/cannot exist" and any mockery about "little green men" or fear about "aliens".

Like many others I ran the SETI@home screensaver, but I abandonned because I have only an old slow computer which took too long to analyse one block.

The diagram deglr6328 http://stuff.mit.edu/people/etekle/Articles/0700crawfordbox5.html summarizes the actual result of SETI searches:

-SETI cannot detect the equivalent of Earth at any distance, even very close (Barnard, Sirius)
-there is nobody at least than 100 light-years aiming at us powerfull radio beams. We know for long that the Arecibo radio telescope can communicate with its equivalent at about 5000 light-years. But nothing such was found.
-there are no type I civilization in our part of the galaxy.
-there is no type II civilization in our galaxy and local cluster.


But these results are still very incomplete, and just reflect a lesser blindness that previous studies. There are still plenty of place for many discreete civilizations and some larger ones. We can only rule out a powerful starwars-like galactic civilization sending a tremendous amount of energy in space. But we have still many possible scenarios:

-many civilization using "environmental friendy" radio communication
-they use laser communication instead, which are believed to be more efficient (thanks to a better focusing, or larger transmission rate).
-they use some quatum non-local technology, which cannot be detected. (I evoke this possibility in my fiction novels "The missing planets" and "Dumria")
-the civilizations evolve in a different way that just increasing technology power (I also evoke this possibility in a third novel to come, and many other possibilities can be imagined)


So, I think, we cannot yet say "there is nobody". We just tested a possibility. We are not with SETI as we are now with Mars, grasping to the last hope of finding life in very special places.


The fact that astrophysics predicts that there can be perhaps millions (or billions) of planets suitable for life in our galaxy, and the fact that we did not received any past visit or did not detected any radio communication, this is a riddle that nobody yet can answer.
It is the equivalent of the astronomy paradox of the black sky. The black sky paradox was solved with an element we could not predict (the universe has a finite past time) so I think some elements are missing to fully understand what we know today about SETI. Some possible hints:

-something we do not know makes civilisation much more rare than expected from astrophysics results
-we were very fast compared to others, and thus appeared among the firsts
-the assumptions describing type I or II civilisations are false
-they use other communication means
-they developed other type of behaviours than just colonialism/predation, and left planets evolve in their own way, so far as avoiding any interference, just like we are doing now with the last unspoiled tribes in Amazonia/Papua.
-they evolve in a different way than just increasing technology achievements in an exponential way.

Examining how life can emerge on a given star system is a matter of astrophysics and biology, but examining how civilisations (like ours) can last and evolve in the future is much more speculative and rather a matter of philosophy.

Posted by: helvick Nov 20 2005, 10:54 AM

I'm also a lapsed SETI@home participant. I had a bunch of systems running under the name Dennis D. Gnome for the Ars Technica Team Lamb Chop group. I think I pulled the plug on the last one in 2002 after I'd clocked in 4331 work units (about 5 years of total CPU time). I had a chunk of systems in a test environment that weren't doing anything most of the time so SETI seemed like a good use for them.

Richard,

You left out out overt aggression as a possible reason for the silence. Even if intelligent life and space faring civilisations are common then even a tiny percentage that tended towards aggression\predation would create very strong evolutionary pressure that encourages "silent" civilisations that tend not to broadcast their presence. Greg Bear's "The Forge of God" and "Anvil of the Stars" set explores some of the possibilities that might result. This is a very pessimistic idea but one that I think is plausible.

There is also the "Intelligence Singularity" concept that Vernor Vinge explores in "Across Realtime". As the overall intelligence\information density of a civilisation rises the rate at which it increases also expands leading to a singularity effect. Since all bets are off at that point it is quite plausible that the resulting civilisation\intelligence might be unrecognizable and undetectable to us. Charlie Stross deals with similar ideas in Singularity Sky, one of the better Sci Fi books of the last year IMO. I'm not 100% sold on the singularity idea but I certainly think that it has merit as an idea beyond being a useful literary conceit.

Posted by: Richard Trigaux Nov 20 2005, 12:20 PM

Richard,

You left out out overt aggression as a possible reason for the silence. Even if intelligent life and space faring civilisations are common then even a tiny percentage that tended towards aggression\predation would create very strong evolutionary pressure that encourages "silent" civilisations that tend not to broadcast their presence. Greg Bear's "The Forge of God" and "Anvil of the Stars" set explores some of the possibilities that might result. This is a very pessimistic idea but one that I think is plausible.

Richard,
There is also the "Intelligence Singularity" concept that Vernor Vinge explores in "Across Realtime". As the overall intelligence\information density of a civilisation rises the rate at which it increases also expands leading to a singularity effect. Since all bets are off at that point it is quite plausible that the resulting civilisation\intelligence might be unrecognizable and undetectable to us. Charlie Stross deals with similar ideas in Singularity Sky, one of the better Sci Fi books of the last year IMO. I'm not 100% sold on the singularity idea but I certainly think that it has merit as an idea beyond being a useful literary conceit.

Posted by: David Nov 20 2005, 03:00 PM

I'm going to add and consolidate some comments on this topic that I made in another section of unmannedspaceflight, where they were out of place (so I can remove them from there).

Nov 14 2005, 05:02 PM
Space is very, very big, and there is a lot of small stuff floating in it. Unless that stuff calls attention to itself in some way, there is no particular reason to investigate it. Even if there were "Vulcans", or some other alien intelligences quite close by, they would have no reason to investigate every tiny asteroid exiting the solar system. Nor would we, in the distant future have any reason to investigate every odd scrap of space debris coming from other systems. I think that any probe leaving our system -- Pioneers, Voyagers, New Horizons -- is permanently lost, to anybody, except in the unlikely event that some future humans decide to track it down and retrieve it.

Any records that we place on these probes therefore have a merely symbolic value. They are the human race's way of saying hello to itself, of patting itself on the shoulder and wishing that it were not so alone. As messages, they are the equivalent of a letter in a bottle, except that bottles set adrift in the sea do occasionally wash ashore. The sea of space is much bigger, and the shorelines are far rarer.

If we intend to communicate to any beings beyond Earth, we need not a message in a bottle but a lighthouse, some sort of beacon that can continuously broadcast the presence of Earth as something extraordinary in the night sky.

Not that, in my opinion, that would do much good. I think the complete failure of SETI to turn up anything thus far tells us one of two things, and probably both: one, that intelligent species, assuming there to be others than humans, are scattered thinly across the universe; there might be no more than one per galaxy. Two, that carrying living beings across interstellar space is very, very difficult, and that optimistic scenarios about colonizing the entire galaxy in a matter of a millennia are untenable.

One thing we can be pretty sure about is that when humans emerge from the solar system, they are not going to find great Star Empires and Space Trading Federations full of busy aliens waiting for them -- or we would have learned of them already. Instead there will be a vast, desolate, and wild sky.

Nov 14 2005, 08:23 PM
I have no problem with putting anything on a probe that doesn't hinder its primary mission, but my understanding is that the odds are not merely slim, they are infinitesimal. That is, we could send out a million such bottle-messages, and the probability that all of them would simply disappear would not be significantly reduced. I think it is truer to say that these messages are poetic expression of human hopes and aspirations, than that they are really meant as messages to alien adventurers. No offense is intended to anyone who has worked on these things and truly believes in them.

I think that any effort to put ourselves in the shoes of a putative extra-terrestrial intelligence, and imagining what they might or might not do to communicate (or willfully fail to communicate with us), before we know that such creatures exist, is absolutely futile. We barely know what intelligence is with respect to Earth animals other than humans. We have no idea what intelligence would look like in non-terrestrial beings. There are no grounds for extrapolating from humans to other intelligent beings that might exist.

The negative results of SETI searches, and our other exploration of nearer space thus far, do not merely provide an "absence of evidence"; they do put definite constraints on what may be out there. One thing we now know is that near space is not packed with beings tending high-powered radio beacons. There could be lots of explanations for that, but the simplest hypothesis is that no intelligent and technologically advanced civiilization exists to do it in this region of space. That may be a disappointing thought; on the other hand, if one simply operates on an unfalsifiable assumption that such beings do exist, and have a bottomless bag of excuses for why they might not be detectable by any any increase in our technological powers, then the hypothesis is no longer strictly scientific.

Posted by: Rakhir Nov 20 2005, 03:11 PM

What is going on with SETI@home?

I have in the past, (...) run the SETI@home screensaver on my computer. I ran it for about 4 years and then uninstalled it. (...) because I saw little in the way of actual science being done with the SETI results we volunteers were all producing and because there seemed to be no plan for any kind of endpoint of the project in the future.

Posted by: helvick Nov 20 2005, 03:51 PM

Good comments David.

There are a couple of additional thoughts that I have in relation to the black sky problem.

We assume that Intelligent civilisations will be detectable remotely because they should leak quite a lot of RF signals. Our current communications technology is still relatively crude, we have only been refining it for a little over a century after all. I think it's reasonable to assume that ever increasing communications efficiency will lead to systems that are substantially less wasteful, much more precisely targeted and in general far more power efficient. Improvements in coding\modulation\signalling techniques are very likely to result in RF signals that are indistinguishable from noise for any but the intended recipient.

It seems very likely to me that the current "lighthouse" mode that we operate in will be a relatively short term thing. It wouldn't surprise me at all if changes in telecomm's over the next century led to a "dark earth" from an RF point of view.

If the above is true as a general rule then there could be hundreds of thousands of advanced civilisations in the galaxy. Some could be very close to us and we still wouldn't be able to detect them from their accidental leakage of RF energy.

The question remains as to why they would also choose not to attempt to communicate deliberately. Cosmic Zoos and Galactic Wildlife Parks that are intended to nurture primitive intelligense seem like a whole load of hokum to me. For starters such things would need galactic scale civilisations and unless our current laws of physics are totally rewritten such concepts just cannot happen, at least not over timescales that have any meaning for civilisation as we know it.

Posted by: deglr6328 Nov 20 2005, 04:07 PM

Posted by: Richard Trigaux Nov 20 2005, 04:51 PM

It is false to say that the SETI results are negative!! They simply found that scifi-like or starwar-like scenarios are not true: there are no giant technologies and galactic dictature, no Independance Day to fear. That is reassuring in a way.

SETI operating from Proxima centauri (the closest star) would not have detected Earth!!!!! Even if Earth-like civilizations are common, SETI still needs an increase in 1000 in sensitivity to have some chance to find a close one.


This result weakens only very little the odds to find intelligent life. But not very much yet, it is not like finding 460°C at the surface of Venus, a simple figure which definitively and dramatically ousted all the dreams of finding luxurient jungles on Venus.


The SETI result still lefts many possibilities open. It just tells us that what we imagined was wrong. If there is life out there, it is just not like we imagined. And it is very interesting to guess what could be their motives, their purposes, their values, even if, of course, this is still untestable in a scientific meaning. This is the process of thinking, and perhaps one day one of these speculations will prove useful or even true.

I do not understand the pessimism of many science-minded people about finding life out there. In the beginning of the 19th century, it was understandable, as the mainstream hypothesis was that the planets formed at time of a close encounter of the Sun with another star, a much rare event which condemned the planet sytems to be only some in a galaxy. But today astrophysics and biology all show that the odds are hight to find life on many planets. So there is many reasons to be optimistic and few to be pessimistic.


I think this pessimism has philosophical reasons more than science reasons. Life elsewhere is felt as threatening, its attitude and even its very existence are felt like a threat to our values, our ego or something of this kind. Or are we so afraid of being considered hoaglandites that we do not consider the possibility of another life form? Be reassured, the SETI institute does not deal with UFOs and abduction...

Posted by: ElkGroveDan Nov 20 2005, 04:56 PM

It's an interesting topic, but it doesn't belong here.

Posted by: ElkGroveDan Nov 20 2005, 05:05 PM

Do you guys realize the search terms that have been added in just the first 8 posts here?

little green men
UFO's
aliens
galactic civilizations
star wars
Vulcans
missing planets
attack with spacefaring technology
Independence Day
unsuspecting worlds
colonize the whole galaxy
Cosmic Zoos
Galactic Wildlife Parks
galactic scale civilisations
Earth-like civilizations

Posted by: David Nov 20 2005, 05:23 PM

I do not understand the pessimism of many science-minded people about finding life out there. [...] But today astrophysics and biology all show that the odds are high to find life on many planets. So there is many reasons to be optimistic and few to be pessimistic.
I think this pessimism has philosophical reasons more than science reasons. Life elsewhere is felt as threatening, its attitude and even its very existence are felt like a threat to our values, our ego or something of this kind.

Posted by: deglr6328 Nov 21 2005, 01:21 AM

EG-Dan, while I share your apprehension about using terms which are sometimes associated with kooks and "ufologists" as they may attract those unsavoury characters to the boards here through google searches, I must differ with you on the notion that we should not discuss these things (SETI) here because of that fact. I think we should never have to censor ourselves here merely because of the existence of hoaxers and paranormalists "out there". I think that there is definitely very interesting and worthwhile discussion on the topic of the search for extraterrestrial intelligence, which can be had here in a rational and skeptically scientific manner. This place is exceptional in that respect. We should never feel forced to shy away from legitimate levelheaded inquiry on these boards and it looks to me like Doug keeps it safe for that here.


Richard, with respect to suspicions of pessimism on ETI among the scientific community, I personally don't see it that way. I fully endorse the view outlined by David above. I'm not a pessimist, just a realist. I would love it so very much if we were to discover ETI in my lifetime and I am hopeful that it is within the realm of (albeit extreme) possibility. But at the same time, I'm not holding my breath. See, the question is of such extremely grave importance and consequence that I want to be 1000% certain that its real when or if we do actually discover it and I think that this kind of stern reservation and insistence on evidence would make such a discovery just that much more wonderful.

Posted by: Richard Trigaux Nov 21 2005, 08:02 AM

EG-Dan, while I share your apprehension about using terms which are sometimes associated with kooks and "ufologists" as they may attract those unsavoury characters to the boards here through google searches, I must differ with you on the notion that we should not discuss these things (SETI) here because of that fact. I think we should never have to censor ourselves here merely because of the existence of hoaxers and paranormalists "out there". I think that there is definitely very interesting and worthwhile discussion on the topic of the search for extraterrestrial intelligence, which can be had here in a rational and skeptically scientific manner. This place is exceptional in that respect. We should never feel forced to shy away from legitimate levelheaded inquiry on these boards and it looks to me like Doug keeps it safe for that here. 

Posted by: Richard Trigaux Nov 21 2005, 08:51 AM

deglr6328 and David, thank you for your replies. I must confess I was a bit angry, but I better understand your arguments.

But I still maintain that there are very large uncertainties about the number of intelligent civilizations, between one per galaxy to millions per galaxy. So we have no reason to choose one of these numbers rather than another. Simply we do not know, and no more than you deglr6328 I expect to meet other beings in my lifetime, and I would be as much cautious than you (especially it happens that I have been deceived by so-called "contactees")


What I should say, in summary, is that the Drake equation is too simplistic, as we must keep with time. The appearance of a civilization is an evolution process, with advances by sudden breakthroughs, and which can be stopped by astrophysical conditions (the star dies, a super-nova close by, etc).


To explain my idea, I would make a simple comparizon with something we have at hand, and even, alas, we have too much of it: the growth of a tumour, a cancer. These mechanisms were unveiled recently, and it is a pity we do not speak much of them. A tumour starts at random, when a cell mutates somewhere and begins to escape its growth control mechanisms. But, as such, this baby tumour is harmless, just mechanical. To become a real deadly cancer, it has to undergo several other mutations. But mutations happen at random, anywhere in the cell mass. So how things take place? simply, if we have, for instance, a probability of one billionth to have a mutation, we think it is very unlikely. But when the cell mass reaches ten or hundred billions, thus the mutation becames MANDATORY. So the tumour gets all the "necessary" mutation, in a deterministic-like way, by steps according to is growth. 1 million cell, step one. 1 billion cells, step two. Ten billion cells, step three, etc. So the tumour evolves in a deteministic-like way, with only probabilistic causes. And this process is so constraining, that only a little number of recognizable types of tumours can form (less than 50), and the same precise types of tumours appear on million of different individuals, without any causal relation between them!!


This simplistic model would be useful, I think, to model the evolution of life on a planet. Like tumours, life evolves by breakthroughs: -drops with a membrane -autocatalytic reactions -DNA like mechanism -multicellular -neurones -brain -emotions, intelligence -civilization -after we cannot foresee, perhaps wisdom. So the model applies, except that the life mass on a planet does not grow exponentially like a tumour, so breakthroughs do not happen at a given moment, there are rather steps, with a probability, linear function of time, to pass to the next step at a given moment. (but if this probability if one half every ten million years, we can expect this step will not last one billion years). On Earth, the longest step was multicellular organisms, three billion years. So we can expect similar times on other planets.

Of course, there are environment factors which constrain the evolution of life. First, the life can modify the chemistry of the planet. (if Earth was sterilized today, life could not reappear). This is even a mandadory step, for instance only an oxygen-rich atmosphere could allow the appearance of movement (muscles) and brain. This kind of considerations could be very constraining: intelligence could appear only in animals on a planet with plants and photosynthesis. Like with tumours, only a small number of types of life would be possible. On the other hand a place like Jupiter's moon Europa could be full of worms and bugs, intelligence will never appear here, by lack of a powerfull energy source like oxygen to feed a large brain.

So the modeling of the evolution of a planet is more complex, with interactions between geologic/chemical/climatic conditions and biology.

The second set of environment factors are rather astrophysical, linked to the evolution of stars and planets. Some hints: Venus could have experienced Earth-like conditions in the beginning. So life could have appeared. But the catastrophic climate change which occured here (greenhouse divergence) stopped it. When? two billion years after formation? So we can guess that only monocellular life could exist at this time, and look for microscopic fossils in venusian mountains, but not for large animal fossils. The same is true with stars a bit larger than the Sun: their life time is too short, an Earth around them would have been destroyed at the stage of bacteria or worms. So it is useless, I think, to search radio signals around large stars. Too small stars like the Barnard star are also too red to give an efficient photosynthesis (although we do not know where is the limit)

At last we must account with catastrophic events: orbit changes, impacts, other star encounters, close supernovas, etc. What is the probability of having a supernova destroying life on a planet? At rough guess it varies widely. The diffuse halo of a galaxy and the bulb are good places. The arms are not very good. Center of globular clusters may be uninhabitable infernos. If we have a probability of a half every 100 million years to be destroyed by a supernova close by, so, with our 4500 million years, we are very unlikely survivors, and in this case civilizations would be indeed very rare, less than one per galaxy, even if life starts at once on every new planet system. But I think that probabilities are much better than half every 100 million years: in the halo there are never supernovas.

So I think the best estimate we can do today about the probability to have civs around there should account with all these probabiliies in a time-dependent scenario more complex that the time-independent Drake model. But, despites this, I think this calculus would still left very wide uncertainties, of many orders of magnittude, about the number of civilization in the Galaxy. That still justifies the SETI program. And anyway SETI is supported by who wants, these people have the right to spent their money in this. And the results already acquired are beginning to bite into the error box about the number and size of civilizations: we now know that there are no galactic dictature and starwars-like galactic network. Great.

Posted by: edstrick Nov 21 2005, 01:18 PM

Richard Trigaux: ".... Too small stars like the Barnard star are also too red to give an efficient photosynthesis...."

Note that there is no problem in general with growing plants under incandescent lamps. The temperature of tungsten filaments is well under the temperature of red dwarf photospheres. The 99.9% bad astronomical art showing crimson red giants and red dwarfs is just that: Bad art.

Evolution on red-dwarf planets may well be pushed to "try" to evolve photosynthetic light absorbing systems that capture light beyond the "red-edge" of chlorophyll, where it's reflectance rises over 10 times from some 5% to some 50%, but that would not be necessary, just helpful.

Posted by: ljk4-1 Nov 21 2005, 06:25 PM

Do you guys realize the search terms that have been added in just the first 8 posts here?

little green men
UFO's
aliens
galactic civilizations
star wars
Vulcans
missing planets
attack with spacefaring technology
Independence Day
unsuspecting worlds
colonize the whole galaxy
Cosmic Zoos
Galactic Wildlife Parks
galactic scale civilisations
Earth-like civilizations

Posted by: Richard Trigaux Nov 21 2005, 07:07 PM

Richard Trigaux:  ".... Too small stars like the Barnard star are also too red to give an efficient photosynthesis...."

Note that there is no problem in general with growing plants under incandescent lamps.  The temperature of tungsten filaments is well under the temperature of red dwarf photospheres.  The 99.9% bad astronomical art showing crimson red giants and red dwarfs is just that: Bad art. 

Evolution on red-dwarf planets may well be pushed to "try" to evolve photosynthetic light absorbing systems that capture light beyond the "red-edge" of chlorophyll, where it's reflectance rises over 10 times from some 5% to some 50%, but that would not be necessary, just helpful.

Posted by: ElkGroveDan Nov 21 2005, 07:09 PM

With that thinking, we better remove the word Mars from this forum, because we all know that will lead to the Mars Face! 
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Posted by: ljk4-1 Nov 21 2005, 07:14 PM

Thanks for the info, edstrick. If I understand well, stars are not really "red" or "yellow", but astrophysicists name them this way because the maximum radiation is in the red, or yellow, but this does not make the stars red or yellow.

And if the 3000°C tungsten lamps allow for photosynthesis, any star can do it, except some brown dwarves, the only stars below the 3000°C.

Back to my statistical analysis, there are perhaps 10 of 50 more time red dwarves than sun-like stars. This multiplies by the same figure the odds to develop photosynthesis (and further civilization).

The setback is that we are not sure that red dwarves have suitable planets. The most commonly accepted hypothesis is that they have, but we have no evidence, and the planets could be too small, from lesser mass and metallicity of the star. In the most extreme case, only recent high-metal yellow stars would have planets large enough to retain air and water. This mades in fact an uncertainty of 20 to 100 about the number of planets able to develop photosynthesis. With other sources of uncertainties, we easily obtain overal uncertainties of 1 over 1 billion about the total number of civilizations. And IN NO CASE we can state that we are closer to one extreme rather from the other.
Red dwarves have another interesting features. Many are very old, as much as 12 billion years. And their overal evolution is much slower, so that the life-supporting period could last for 10 billion years, much more than for Earth (due to the slow evolution of the sun). So, if ancient red dwarves have suitable planets, we have the best chances to find something there. From where the interest of an effort to detect eventual Earth-like planets specially around close red dwarves, if possible with low metallicity.

Posted by: Richard Trigaux Nov 21 2005, 07:18 PM

With that thinking, we better remove the word Mars from this forum, because we all know that will lead to the Mars Face! 

Posted by: Richard Trigaux Nov 21 2005, 07:33 PM

Have you seen the recent National Geographic Channel special titled Extraterrestrial?  Its first hour depicts speculations about life on a planet
circling a red dwarf sun, complete with dealing with the issues of such stars
creating massive flares.

http://channel.nationalgeographic.com/channel/extraterrestrial/

The Discovery Channel also came out with its own special on an alien world
and its life forms, based on the 1990 book Expedition by Wayne Barlowe, which you can learn more about here:

http://www.discoverychannelasia.com/alienplanet/index.shtml

Posted by: Richard Trigaux Nov 21 2005, 07:49 PM

The way google and other search engines work when you enter multiple search terms is that they look for frequency of terms on a page, as well as proximity of the terms to each other.

So a search for "Mars Pathfinder" or "Mars Opportunity" will likely turn up this site.

Prior to this thread, a search on "Mars alien civilization attacks by UFO's" would not have resulted in a hit here, it would have taken the kook to OTHER places.

Posted by: deglr6328 Nov 22 2005, 01:35 AM

We probably should not be so quick to dismiss the possibility of photosynthesis on planets orbiting stars which dominantly radiate in the IR.....


http://www.the-scientist.com/news/20050621/01 and the http://www.pnas.org/cgi/content/full/102/26/9306?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=photosynthetic+hydrothermal&searchid=1132623122425_9747&stored_search=&FIRSTINDEX=0&journalcode=pnas.

Posted by: jamescanvin Nov 22 2005, 02:56 AM

perhaps that if the people who do searches like "Mars alien civilization attacks by UFO's" find this forum, they will get instruction, and realise that those who spread false theories are kooks.

Each time I was speaking of kooks on this site, it was alway about the spreaders of false theories. That 20% of the population believe them is not because 20% of the population are mad, it is because they are not enough instructed, or they are not confident with a society wich deceived them in a way or another. In such a situation, kooks have an easy play. If, with this forum, we can contribute to revert this situation, it would be of some use, not just a pass time for us.

A wise caution would be to use a language more accessible to common people, avoid "scientific style" and obscure abbreviations, and when we use an uncommon word, give the explanation. I began to do so recently , realizing that more and more people are reading us, not just specialist or enlightened amateurs.
Thas does not forbid to expell real kooks when there are some. Or to answer briefly but accurately to suspicious questions, as Doug used to do in many occasions. He did in this way, I think, to avoid to straightforwardly rebuff people who are just mislead by kooks, but who are not kooks themselves.

Posted by: Richard Trigaux Nov 22 2005, 07:13 AM

We probably should not be so quick to dismiss the possibility of photosynthesis on planets orbiting stars which dominantly radiate in the IR.....
http://www.the-scientist.com/news/20050621/01 and the http://www.pnas.org/cgi/content/full/102/26/9306?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=photosynthetic+hydrothermal&searchid=1132623122425_9747&stored_search=&FIRSTINDEX=0&journalcode=pnas.

Posted by: ljk4-1 Nov 22 2005, 02:28 PM

Paper: astro-ph/0511583

Date: Fri, 18 Nov 2005 21:35:43 GMT (30kb)

Title: Hot Jupiters: Lands of Plenty

Authors: David Charbonneau

Comments: 8 pages, 2 figures, summary of conference "The Tenth Anniversary of
51 Peg b: Status and Prospects for Hot Jupiter Studies", held August 22 - 25,
2005
\\
In late August 2005, 80 researchers from more than 15 countries convened for
a 4-day conference entitled ``The Tenth Anniversary of 51 Peg b: Status and
Prospects for Hot Jupiter Studies''. The meeting was held at l'Observatoire de
Haute-Provence, the location of the 1.93-m telescope and ELODIE spectrograph
used to discover the planetary companion to 51 Peg roughly 10 years ago. I
summarize several dominant themes that emerged from the meeting, including (i)
recent improvements in the precision of radial velocity measurements of nearby,
Sun-like stars, (ii) the continued value of individual, newly-discovered
planets of novel character to expand the parameter space with which the theory
must contend, and (iii) the crucial role of space-based observatories in
efforts to characterize hot Jupiter planets. I also present the returns of an
informal poll of the conference attendees conducted on the last day of the
meeting, which may be amusing to revisit a decade hence.

\\ ( http://arXiv.org/abs/astro-ph/0511583 , 30kb)

Posted by: ljk4-1 Nov 22 2005, 04:23 PM

I have been wondering whatever became of The Planetary Society's Project BETA Radio SETI program, begun ten years ago, ever since the 84-foot Harvard radio dish broke and fell during a windstorm in March of 1999.

The TPS Web site has an article from 2000 describing and showing a repair job undeway:

http://seti.planetary.org/BETA/default.html

But when I went to Harvard University's Oak Ridge Observatory site, I found out that the BETA dish has since been "retired":

http://cfa-www.harvard.edu/oir/OakRidge/oak.ridge.html

I also learned from there, to my surprise, that the 61-inch telescope that had conducted their Optical SETI program since 1998 has also been retired - retired in this case meaning dismantled!

Why didn't the TPS or Harvard or someone inform us about this?

A few years back, TPS began a new Optical SETI project with much fanfare. I looked on their Web site but could find no new updates on it since 2002 (with lots of broken links here), when it was supposed to have its "first light":

http://seti.planetary.org/OsetiConstruction2.htm

The latest version of their Optical SETI page also reveals no recent news on this project:

http://planetary.org/programs/projects/seti_optical_searches/

So what is happening with what is supposed to be the "largest Optical SETI project east of the Mississippi"? Is it still being built? Is it up and running? Has it too been abandonded? Has the TPS been slipping away from SETI ever since Carl Sagan's passing, as I suspect?

I and many other have supported this project financially as well as verbally, so I would hope to at least know what progress is being made - and why BETA was abandonded. Why didn't TPS at least transfer it to another radio telescope?

Posted by: elakdawalla Nov 22 2005, 06:41 PM

I have been wondering whatever became of The Planetary Society's Project BETA Radio SETI program, begun ten years ago, ever since the 84-foot Harvard radio dish broke and fell during a windstorm in March of 1999. 

Posted by: Bob Shaw Nov 22 2005, 06:50 PM

The way google and other search engines work when you enter multiple search terms is that they look for frequency of terms on a page, as well as proximity of the terms to each other.

So a search for "Mars Pathfinder" or "Mars Opportunity" will likely turn up this site.

Prior to this thread, a search on "Mar5 a1ien c1vilization a77acks by U70's" would not have resulted in a hit here, it would have taken the kook to OTHER places.

Posted by: David Nov 22 2005, 07:40 PM

The way google and other search engines work when you enter multiple search terms is that they look for frequency of terms on a page, as well as proximity of the terms to each other.

Posted by: ljk4-1 Nov 22 2005, 07:48 PM

Hi ljk4-1, all of these older projects that you mention unfortunately predate my joining the staff at The Planetary Society, and they're out of my usual purview, so I'm afraid I don't know any information to give you.  I have forwarded your comments to the people here who particpate in the SETI projects.

I do know, however, that we continue to support SETI projects financially thanks to member dues and donations, and that we currently have active projects in http://www.planetary.org/programs/projects/seti_optical_searches/ and http://www.planetary.org/programs/projects/search_for_extraterrestrial_life/seti_radio_searches/ SETI, along with our other http://www.planetary.org/programs/list/ in technology development, Mars exploration, Near Earth Objecs searches, extralsolar planets, and others.  The stuff on our website is a little thin right now because we just completed our redesign and have only filled out the barest skeleton of necessary content.  I know that filling in more depth in the SETI section (as well as all the rest of the projects) is one of the priorities.  Here's the most recent update from our Director of Projects, Bruce Betts, about our SETI work, which was published in the September/October 2004 issue of The Planetary Report:

Posted by: elakdawalla Nov 22 2005, 08:11 PM

Three years with no substantial news, positive or negative, on the project is a bit surprising.

Posted by: elakdawalla Nov 22 2005, 08:16 PM

Perhaps what bothers you is not so much the phrases, or the possibility of them being detected by a web-searching anomalist, as their context?  --that is, the sense that a scientific forum such as this is degraded by the discussion of anything so "science fictional" as SETI?

Posted by: ElkGroveDan Nov 22 2005, 08:28 PM

Chalk it up to having only one full-time and two part-time people here who develop the entire Society website...so much to do, so little time.   Seriously, we've heard you and will try to get more information up there... --Emily

Posted by: elakdawalla Nov 22 2005, 09:50 PM

Emily have you thought about an overt effort to recruit qualified staff volunteers?  I know that Southern California is full of brilliant retired and semi-retired people with vast engineering and science backgrounds.

Posted by: Richard Trigaux Nov 23 2005, 07:48 AM

What you say about science writing is very true, emily.
With the only paper I have ever published (in economy) I had to expurge any emotion and most of philosophy/society implications (however there are much in economy). It is a bit sad, and on my site I rather presented the results in the form of a game, of novels, while summarizing up in some sentences, which are enough to explain it to the layperson.

In physics it is the same, and in space exploration there is also a high emotional content. I remember when I was a child, Mars was stil represented with the Schiaparelly maps (with the "channels") and Titan or Venus were just names, about which we knew exactly zero. Now we are getting out of our Earth craddle and exploring the wold!

Beyond the ordinary appearances such as a peaceful sun bathed afternoon among meadows and trees, there is this fantastic cosmos, baffling distances, incredible temperatures, other strange worlds, astounding time at the source of our lives, and we can abruptly feel the difference when suddenly the Sun hides behind the Moon (I whatched the 1998 eclipse). Then the day disappears as if a lamp was switched off, there are no more peaceful meadows but incredible masses of stone moving into the cosmos at unconceivable speeds, there is no more friendly sushine but a thermonuclear furnace which its red flames around the moon... And the guies who came with expensive telescopes and cameras just left them down, and gaze at this unforgettable view.

And then, as quickly as it came, it is over, the abyss door closes, the sky becomes blue again, the birds resume singing, only a chill remains of the strange vision.

Wow

Posted by: dvandorn Nov 23 2005, 04:16 PM

I can also really relate to Emily's discussion of writing technique. My natural writing style is rather like Emily describes hers -- long sentences with conversational-tone punctuation. And sentence fragments. For effect.

At least, in my case, there is some sort of switch I can throw in my brain, and I can just start cutting the sentences down as I write them. And I can go through what I just wrote, give it a short once-over, et voila, short, action-verb sentences.

My first drafts are usuallly in final draft or next-to-final-draft shape. I just have this little problem with typos -- in specific, with hitting the space bar just a fraction of a millisecond early. One of the worst examples of this is when I write the short connecting phrase "to the"... it tends to come out "tot he."

Ever tried to use a spell checker to find something like that? When the words "tot" and "he" are both perfectly valid English words? Considering the subject matter I'm usually dealing with, though, I can just do a word search on "tot" and find every instance...

-the other Doug

Posted by: ljk4-1 Nov 28 2005, 06:32 PM

SETI@home killed off ?

Placed in sarcophagus rises again

http://www.theinquirer.net/?article=27885

By: Nick Farrell

Wednesday 23 November 2005, 07:18

DISTRIBUTED computing experiment SETI@home will be switched off on
December 15 as it becomes part of the Berkeley Open Infrastructure for
Network Computing (BOINC).

BOINC has been developed at UC Berkeley as a framework for volunteer
computing projects like SETI@home.

According to a press release, those who are currently using SETI@home are
being asked to visit here for instructions.

The workunit totals of users and teams will be frozen at that point, and
the final totals will be available on the web.

The BOINC site will allow boffins to build other volunteer computing
projects in areas like molecular biology, high-energy physics, and climate
change study.

A spokesSeti said that those who want to keep looking for aliens can do
so, but they will also be able to donate computer time studying climate
change or other BOINC projects.

Posted by: dvandorn Nov 28 2005, 10:17 PM

Hmmm... upon reading this thread last week, I went ahead and started running SETI processing again. I've got a much better system now than I did back when I ran it a few years ago, and I figured it would be more useful now.

When I went out to the SETI@Home site to download the software again, I got the BOINC client. It's been running fine for me over the past week and a half or so.

So, a lot of people are already using the BOINC client, it would seem. It's sort of a nice name, too...

-the other Doug

Posted by: Richard Trigaux Nov 29 2005, 07:51 AM

What does this means?

If I understand well, the work will continue, but in place of processing only SETI we will have to compute any other data from other experiments, without being given the choice.

Historically, as far as I know, what is now the BOINC was first developped for SETI, and after used by other experiments.

Is this just a technical/commercial move, or another tortuous mean to twart SETI? If someone has more precise info, please tell, at least to dissipate any doubt.

Posted by: jaredGalen Nov 29 2005, 09:52 AM

What does this means?

If I understand well, the work will continue, but in place of processing only SETI we will have to compute any other data from other experiments, without being given the choice.

Posted by: Richard Trigaux Nov 29 2005, 10:29 AM

It's okay, , the whole process of distributed computing projects has been streamlined I guess you could say. The BOINC client now supports processing data from other projects, some of which are mentioned above.

A user simply picks which project they want to work on, or multiple projects and allocate processor time as they want. If you do 2 projects you can allocate time 80% to one and only 20% to the other if you want.

It's really quite good I think, makes everything much better rather than having a client for each number crunching application you want to join.

Posted by: ljk4-1 Nov 29 2005, 03:35 PM

Scientists, be on guard ... ET might be a malicious hacker

The Guardian November 25, 2005

*************************

Richard Carrigan, a particle
physicist at the US Fermi National
Accelerator Laboratory, believes the
SETI@home project is putting Earth's
security at risk by distributing the
signals they receive to computers
all over the...

http://www.kurzweilai.net/email/newsRedirect.html?newsID=5064&m=7610

Posted by: Richard Trigaux Nov 29 2005, 09:51 PM

Scientists, be on guard ... ET might be a malicious hacker

The Guardian November 25, 2005

*************************

Richard Carrigan, a particle
physicist at the US Fermi National
Accelerator Laboratory, believes the
SETI@home project is putting Earth's
security at risk by distributing the
signals they receive to computers
all over the...

http://www.kurzweilai.net/email/newsRedirect.html?newsID=5064&m=7610

Posted by: ljk4-1 Nov 29 2005, 10:19 PM

At least one SETI group is working under the assumption that ETI are using the Internet to understand humanity:

http://www.ieti.org/index.html

As anthropologists like to say, you learn a lot more about a culture by sifting through their junk than through their official records.

No wonder they haven't bothered to contact us.

Posted by: TheChemist Nov 30 2005, 12:07 AM

Posted by: Richard Trigaux Nov 30 2005, 11:17 AM

WE can seriously consider that, in the assumption some extra-terrestrial civilization is actually observing us, that they will try to connect to the Internet. After all, it is the best way to have a complete view of our anatomy that they will not find on TV

The most easy to observe from outer space are military radars and large power analog TV broadcasts. They could learn much about our technology level, and anamog TV is easy to decode into sounds and images. This could be done from 100 light years and more with the extra-terrestrial equivalent of the Arecibo telescope used for our SETI. But they will have to wait still some more tens of years for receiving us...

Receiving the internet signals is another story. These signals often travel by cables, and when they go in space, they are undecipherable and mixed altogether into packets, so what they could see only a randon mixture of millions of different pages, if even they manage to decode texts and simple gif images.

So to observe the Internet, an extra-terrestrial civilization would need to INTERACT with it: to receive and to SEND signals to it. For this, they will need a probe near Earth to achieve a connexion: the probe would have to simulate a cell-phone, Wi-Fi aparatus or something like that. This is possible only if the probe is near Earth, in order to reply in no more than some seconds: on a far orbit, on the Moon, at worse on the L1 Lagrange point. And it will have to use a narrow beam, and be itself radar-stealth and black. Or they may have somebody on Earth working for them...

Once on the Internet, they can observe all our pages (shame for many) and use Google for any search and study about our customs, languages or thinking. (It would be very easy to learn most languages using Google, I even use it as an orthography corrector)

Once I had in the stats of my UFO page "unknown origin"...

But it they do so, while keeping unoticed, they will simply have to connect using a free account with an ISP which do not check for identities: Yahoo, free.fr, etc... In this case, it will be very difficult to spot them. Only a large monitoring of the activity of all the accounts could allow to detect them.

So perhaps there is actually extraterrestrial agents studying this page...

But there are however so many large "if", that this idea is rather a scifi prospect than an actual concern.

Posted by: lyford Nov 30 2005, 06:54 PM

Of course, they would need a compatible operating system... would ET be Mac or PC or
&$(#*$@nix or what?

http://www.billhusler.com/public/commercials/powerid4.mov

Not to mention the translation issues... just ask " It is quick the ?"

Posted by: Richard Trigaux Nov 30 2005, 07:35 PM

Of course, they would need a compatible operating system... would ET be Mac or PC or
&$(#*$@nix or what?

http://www.billhusler.com/public/commercials/powerid4.mov

Not to mention the translation issues... just ask " It is quick the ?"

Posted by: lyford Nov 30 2005, 09:45 PM

Well, it started OS independent - but with all the bells and whistles that folks add on to make their pages look cool, things get complicated quickly - as even seen http://www.unmannedspaceflight.com/index.php?showtopic=1628 amongst this august company. And don't get me started on http://en.wikipedia.org/wiki/Activex#Internet_Security.....

But your earlier point about proximity needed for "eavesdropping" is very salient. Based upon a sample set of one (our technological history), it would appear that the loud emission style broadcast age is short lived - we are switching to directed, cabled transmission and low powered wireless. Which would mean that you only get a "Honeymooners to Survivor" light bubble of about 50 years to catch someone before they get quiet in the spectrum again. I shudder to think that our species is being represented to the galactic neighborhood by http://en.wikipedia.org/wiki/Three%27s_Company

And forget about hearing anything from the http://en.wikipedia.org/wiki/Dyson_sphere advanced races out there....

Posted by: Richard Trigaux Dec 1 2005, 07:17 AM

Well, it started OS independent - but with all the bells and whistles that folks add on to make their pages look cool, things get complicated quickly - as even seen http://www.unmannedspaceflight.com/index.php?showtopic=1628 amongst this august company.  And don't get me started on http://en.wikipedia.org/wiki/Activex#Internet_Security.....

But your earlier point about proximity needed for "eavesdropping" is very salient.  Based upon a sample set of one (our technological history), it would appear that the loud emission style broadcast age is short lived - we are switching to directed, cabled transmission and low powered wireless.  Which would mean that you only get a "Honeymooners to Survivor" light bubble of about 50 years to catch someone before they get quiet in the spectrum again.   I shudder to think that our species is being represented to the galactic neighborhood by http://en.wikipedia.org/wiki/Three%27s_Company 

And forget about hearing anything from the http://en.wikipedia.org/wiki/Dyson_sphere advanced races out there....

Posted by: lyford Dec 1 2005, 05:48 PM

Richard, your points are all very good.

I am struck though by how contingent any search like this is upon our current state of technology - it wouldn't be so long ago that a SETI search would consist of looking for fires burning in geometrical patterns on the Moon or Mars....

It could be that Earth is being flooded with signals but in a technological medium that we can't even realize yet.

But it seems to even make the odds worse that we would be listening at the right time AND in the right way at the exact space/time coinciding with a species sending a message.

While I think it doesn't hurt to keep your ears, eyes, sensor platforms, etc, open, (and I do have SETI@home running on one of my boxes), now that I consider it I think I would rather donate my spare CPU cycles to a NEO hunt or something more practical if it existed.

Posted by: Richard Trigaux Dec 1 2005, 06:55 PM

Richard, your points are all very good. 

I am struck though by how contingent any search like this is upon our current state of technology - it wouldn't be so long ago that a SETI search would consist of looking for fires burning in geometrical patterns on the Moon or Mars....

It could be that Earth is being flooded with signals but in a technological medium that we can't even realize yet.

But it seems to even make the odds worse that we would be listening at the right time AND in the right way at the exact space/time coinciding with a species sending a message.

While I think it doesn't hurt to keep your ears, eyes, sensor platforms, etc, open, (and I do have SETI@home running on one of my boxes), now that I consider it I think I would rather donate my spare CPU cycles to a NEO hunt or something more practical if it existed.  

Posted by: ljk4-1 Dec 1 2005, 09:44 PM

SETI and Intelligent Design

http://www.space.com/searchforlife/seti_intelligentdesign_051201.html

Many readers don't know that SETI research has been offered up in support of
Intelligent Design. Let's take a minute to fix this, shall we?

Posted by: Rakhir Dec 1 2005, 10:18 PM

I think I would rather donate my spare CPU cycles to a NEO hunt or something more practical if it existed. 

Posted by: Richard Trigaux Dec 2 2005, 09:27 AM

SETI and Intelligent Design

http://www.space.com/searchforlife/seti_intelligentdesign_051201.html

Many readers don't know that SETI research has been offered up in support of
Intelligent Design. Let's take a minute to fix this, shall we?

Posted by: ljk4-1 Dec 2 2005, 03:26 PM

Paper: astro-ph/0512013

Date: Thu, 1 Dec 2005 03:28:14 GMT (229kb)

Title: Biological Effects of Gamma-Ray Bursts: Critical distances for severe
damage on the biota

Authors: Douglas Galante, Jorge Ernesto Horvath

Comments: 27 pages, 3 figure, submitted to Astrobiology
\\
We present in this work a unified, quantitative synthesis of analytical and
numerical calculations of the effects caused on an Earth-like planet by a
Gamma-Ray Burst (GRB), considering atmospheric and biological implications. The
main effects of the illumination by a GRB are classified in four distinct ones
and analyzed separately, namely the direct gamma radiation transmission, UV
flash, ozone layer depletion and cosmic rays. The effectiveness of each of
these effects is compared and lethal distances for significant biological
damage are given for each one.

We find that the first three effects have potential to cause global environmental changes and biospheric damages, even if the source is located at great distances (perhaps up to ~ 100 kpc). Instead, cosmic rays would only be a serious threat for very close sources. As a concrete example of a recorded similar event, the effects of the giant flare from SGR1806-20 of Dec 27, 2004 could cause on the biosphere are addressed.

In spite of not belonging to the so-called 'classical' GRBs, most of the
parameters of this recent flare are well-known and serve as a calibration for
our study. We find that giant flares are not a threat for life in all practical
situations on Earth, mainly because it is not as energetic, in spite of being
much more frequent than GRBs.

\\ ( http://arXiv.org/abs/astro-ph/0512013 , 229kb)

Posted by: Richard Trigaux Dec 2 2005, 04:12 PM

This is interesting info. With this kind of data we can assess the probability of successfully completing the long duration evolutionary steps necessary to the appearance of life, multicellular life, and civilization.

Unfortunately if only one gamma ray burst is able to sterilize a whole galaxy, that makes this probability very weak. But they speak of environment change, not of complete disappearance (anyway only one side of a planet is directly illuminated). So there could be rather mass extinctions, or strong evolutionary pressure. The most critical period being between getting out of water and the appearance of civilization, which on Earth was fast, only 300 million years.
Anyway zone of intense stellar formation (propicious to gamma ray bursts) are the worse place for life. At the extreme only giant galaxies like Virgo (with only old stars) could shelter many civilizations, and we would be lucky or among the firsts in our galaxy, even if life started on many planets.

In a general way gamma ray bursts were more common in the past, and it may happen that only now life is beginning to flourish.

That giant flares are relatively harmless in on the other hand rather a good new, as many stars propitious to life are flare-prone. But is this study speaking of the effect of the flare on neighbouring systems, or on a planet of the star which is emitting a flare? If a flare is as luminous as the star itself, and lasts several days, it will heat a planet twice as usual!

Posted by: chris Dec 2 2005, 04:37 PM

Unfortunately if only one gamma ray burst is able to sterilize a whole galaxy, that makes this probability very weak.

Posted by: Richard Trigaux Dec 2 2005, 05:34 PM

Richard,

Current theories suggest that GRB's can't sterilize an entire galaxy, as the radiation is emitted in two very narrow jets

Chris

Posted by: ljk4-1 Dec 5 2005, 04:23 PM

Paper: astro-ph/0512053

Date: Fri, 2 Dec 2005 02:47:13 GMT (391kb)

Title: Atmospheric Biomarkers and their Evolution over Geological Timescales

Authors: L. Kaltenegger, K. Jucks, W.Traub

Comments: for high resolution images see

http://cfa-www.harvard.edu/~lkaltenegger

Journal-ref: CUP, IAUC 200 proceedings, 2005
\\
The search for life on extrasolar planets is based on the assumption that one
can screen extrasolar planets for habitability spectroscopically. The first
space born instruments able to detect as well as characterize extrasolar
planets, Darwin and terrestrial planet finder (TPF-I and TPF-C) are scheduled
to launch before the end of the next decade. The composition of the planetary
surface, atmosphere, and its temperature-pressure profile influence a
detectable spectroscopic signal considerably.

For future space-based missions it will be crucial to know this influence to interpret the observed signals and detect signatures of life in remotely observed atmospheres.

We give an overview of biomarkers in the visible and IR range, corresponding to the TPF-C and TPF-I/DARWIN concepts, respectively. We also give an overview of the evolution of biomarkers over time and its implication for the search for life on
extrasolar Earth-like planets. We show that atmospheric features on Earth can
provide clues of biological activities for at least 2 billion years.

\\ ( http://arXiv.org/abs/astro-ph/0512053 , 391kb)

Posted by: Richard Trigaux Dec 5 2005, 06:31 PM

Paper: astro-ph/0512053

Date: Fri, 2 Dec 2005 02:47:13 GMT   (391kb)

Title: Atmospheric Biomarkers and their Evolution over Geological Timescales

Authors: L. Kaltenegger, K. Jucks, W.Traub

Comments: for high resolution images see

  http://cfa-www.harvard.edu/~lkaltenegger

Journal-ref: CUP, IAUC 200 proceedings, 2005
\\
......

\\ ( http://arXiv.org/abs/astro-ph/0512053 ,  391kb)

Posted by: Richard Trigaux Dec 5 2005, 07:13 PM

Another interesting use of these (future) result will be to plot the number of planets according to the age of the star. Such a plot will allow to assess the mean duration of the longest evolutionary steps, such as oxydization of reductive materials (oxygen can appear only after this stage, which lasted more than 2 billion years on Earth) and the appearance of multicellular life (which took 3 to 4 billion years on Earth). If we were very lucky and these steps take usually more time, ther will be few civs around. If we were mean (or unlucky) there would be civs on every suitable planets. (On Earth the passage from plant covering, refered as the "red edge" in the article, occured only 0.44 billion years ago, so we can expect it is usually much shorter than the two previous).

Eventually this plot could allow to detect the past effects of a gamma ray burst, if only planets under a given age have life.

Posted by: ljk4-1 Dec 12 2005, 03:10 PM

Review: Life as We Do Not Know It
---
The nascent field of astrobiology faces a number of challenges,
including just how alien life on other worlds might be. Jeff Foust
reviews a book by a leading astrobiologist that tackles the nature of
life and its prospects elsewhere in the solar system.

http://www.thespacereview.com/article/516/1

Posted by: ljk4-1 Dec 12 2005, 03:41 PM

The Call That Is Important To Us All

Leigh Dayton

Science Writer

Earthlings haven't yet heard from ET, but leading questers for cosmic company are getting ready to take the call... just in case.

They've established an international committee to set the etiquette for inter-galactic contact. And Sydney-based cosmologist Paul Davies just took on the top job.

"We need to get the protocol correct and clarified," noted Professor Davies, with Macquarie University's Australian Centre for Astrobiology.

"If ET called tonight we'd be in a bit of a muddle about it all," he added, speaking prior to his first meeting as head of the Post-Detection Science and Technology Taskgroup.

The body is part of the International Academy of Astronautics and was founded by radio-astronomer Jill Tarter of the Search for Extraterrestrial Intelligence (SETI) Institute in California.

"We want the correct details about the discovery event and any interpretation made about it to get out there," commented Dr Tarter, in Australia for a lecture tour supported by Sydney University's Centre for Human Aspects of Science and Technology.

According to Dr Tarter - whose SETI exploits were portrayed by Jodie Foster in the 1997 film Contact - if a signal from ET is detected it must be verified quickly and the news spread widely to ensure it's not "co-opted" by interest groups or politicians.

"Another caveat is that (scientists) will not transmit a reply until there's a global consensus about whether to reply and what should be said," Dr Tarter claimed.

The rest is here:

http://www.theaustralian.news.com.au/common/story_page/0,5744,17491815%5E29098,00.html

Posted by: Richard Trigaux Dec 12 2005, 03:58 PM

Review: Life as We Do Not Know It
---
The nascent field of astrobiology faces a number of challenges,
including just how alien life on other worlds might be. Jeff Foust
reviews a book by a leading astrobiologist that tackles the nature of
life and its prospects elsewhere in the solar system.

http://www.thespacereview.com/article/516/1

Posted by: ljk4-1 Dec 12 2005, 04:16 PM

Paper (*cross-listing*): physics/0512062

Date: Wed, 7 Dec 2005 19:40:50 GMT (20kb)

Date (revised v2): Fri, 9 Dec 2005 17:55:41 GMT (20kb)

Title: A Solution to the Fermi Paradox: The Solar System, part of a Galactic
Hypercivilization?

Authors: Beatriz Gato-Rivera

Comments: Conference for general public given in the World Mystery Forum 2005,
Interlaken (Switzerland), November 2005. Latex, 16 pages. Footnote 8 added

Subj-class: Popular Physics
\\
I introduce the Fermi Paradox and some of its solutions. Then I present my
own solution which includes two proposals called the Subanthropic Principle and
the Undetectability Conjecture. After discussing some consequences of this
solution, I make some comments about brane world scenarios and their potential
to strengthen the Fermi Paradox. Finally, in the appendix I have included some
questions and answers that came up during this Forum.

\\ ( http://arXiv.org/abs/physics/0512062 , 20kb)

Posted by: Richard Trigaux Dec 12 2005, 05:11 PM

Posted by: ljk4-1 Dec 12 2005, 07:55 PM

National Geographic Channel - Monday, December 12, 2005:

WORLD PREMIERE - Naked Science: "Close Encounters" at 9P et/pt

Has planet Earth ever had close encounters with aliens? How did they
get here? Did any survive? Join us for a provocative look at whether
we've ever hosted visitors from outer space.

"Extraterrestrial" at 10P et/pt

This groundbreaking show creates two worlds that scientists believe
could exist in our own Milky Way galaxy - putting evolution in
motion to investigate what life-forms could survive there.

Is it Real?: "UFOs" at 8P et/pt

Numerous people believe they have spotted glowing alien spacecraft
hovering over Earth - and some even claim to have been abducted by
them. Scientists and astronomers dissect video footage and anecdotal
evidence as we consider the case for the existence of flying saucers
and UFOs.

Watch a preview.

http://ng.chtah.com/a/tBDnbqvASJ4TXAa$eR0AOOv6R.ASJ-ROmH/ngs4

Posted by: David Dec 12 2005, 09:31 PM

Interesting article.

-On Earth, only bilaterals primitive beings (with a right-left symmetry) were able to evolve toward intelligence. This does not rule out octupus-shaped intelligent beings, but makes bilaterals more probable.

Posted by: David Dec 12 2005, 10:28 PM

Posted by: tty Dec 13 2005, 07:03 PM

Not sure, still under discution. But this raises the probable number of civilizations by something like 1000!

In fact the beam feature changes nothing: it means that, the narrower the beam,  for one beam we see, the more numerous we don't see. So the overal probability to have a planet killed by an hypernova or GRB does not depends on the radiation being focused or not!!

Again the probable number of civs is diminushed by 1000...

Posted by: Richard Trigaux Dec 13 2005, 07:32 PM

Octopodes and other molluscs are just as bilateral as the rest of us; they do have tentacles arranged in a ring, but they have one eye to a side (and other, more basic structures that are definitely bilateral).
 
  The fact that humans and every other plausible Terrestrial candidate for sentience, let alone intelligence, is bilaterally symmetric, is just a reflection of the extraordinary success of bilaterian fauna (which is a monophyletic clade by the way) in exploiting almost all niches for mobile macroscopic organisms.  As the only non-bilaterian metazoans are things like sponges, jellyfish, corals, comb-jellies, hydras, sea anemones, cubozoans and other marine fauna, the result is that macroscopic land fauna are (to the best of my knowledge) 100% bilaterian.  And while one can imagine intelligent sea life evolving, it's hard to imagine sea-creatures also having a body-shape that would be conducive to tool use and other desiderata of civilization.

Posted by: Richard Trigaux Dec 13 2005, 07:46 PM

Actually I don't see how a GRB could ever sterilize even a single planet since it only lasts a very short time, and can therefore never hit more than one side of a planet.

Even a supernova that lasts longer can only affect a whole planet if it is exactly in the equatorial plane, otherwise part of one hemisphere would always be shielded.

...

tty

Posted by: Richard Trigaux Dec 13 2005, 08:11 PM

The Call That Is Important To Us All

Leigh Dayton

Science Writer

Earthlings haven't yet heard from ET, but leading questers for cosmic company are getting ready to take the call... just in case.

They've established an international committee to set the etiquette for inter-galactic contact. And Sydney-based cosmologist Paul Davies just took on the top job.

"We need to get the protocol correct and clarified," noted Professor Davies, with Macquarie University's Australian Centre for Astrobiology.

"If ET called tonight we'd be in a bit of a muddle about it all," he added, speaking prior to his first meeting as head of the Post-Detection Science and Technology Taskgroup.

The body is part of the International Academy of Astronautics and was founded by radio-astronomer Jill Tarter of the Search for Extraterrestrial Intelligence (SETI) Institute in California.

"We want the correct details about the discovery event and any interpretation made about it to get out there," commented Dr Tarter, in Australia for a lecture tour supported by Sydney University's Centre for Human Aspects of Science and Technology.

According to Dr Tarter - whose SETI exploits were portrayed by Jodie Foster in the 1997 film Contact - if a signal from ET is detected it must be verified quickly and the news spread widely to ensure it's not "co-opted" by interest groups or politicians.

"Another caveat is that (scientists) will not transmit a reply until there's a global consensus about whether to reply and what should be said," Dr Tarter claimed.

The rest is here:

http://www.theaustralian.news.com.au/common/story_page/0,5744,17491815%5E29098,00.html

Posted by: tty Dec 13 2005, 09:54 PM

Note that "severe effect on the biota" does not means that the evolution is stopped, on the countrary such events may speed it up, as with the Chixculub impact which allowed the supremacy of mammals, hot blooded animals which were able to develop intelligent brains, when cold-blooded reptilians could not.

Posted by: ljk4-1 Dec 14 2005, 03:06 AM

Interesting paper, ljk4-1.

The problem if "a signal is found" is twofold:
-avoid any mistake, and thus avoiding publishing before being sure
-avoid any censorship, and thus publishing as fast as possible.

This is contradictory, so it needs a special organization such as:
-contact many scientists under secrecy
-mobilize great science instruments in higher priority
-protect the evidences
-spread the information to the public by several different and numerous channels, especially internet sites in several countries

Hey hey SETI begins to look like a sci-fi story...

With my opinion, the first evidence of an extraterrestrial civ is very likely to be unintentionnal (from them). But if we find a probe orbiting around our sun...

The scenario in the "contact" movie is not realistic: if other civilizations reached a higher level, they are much more likely to have reached for long ago, not just in the same time than ours. So they are very likely to know our existence from very long too, not just discovering us when the first TV broadcast is send away. IF THERE ARE TECHNOLOGICAL EXTRATERRESTRIAL INTELLIGENCES, THEY KNOW OUR EXISTENCE.  That they did not tried to actually contact us is a bit surprising. There is a wide range of very different explanations.

Posted by: ljk4-1 Dec 14 2005, 05:06 AM

Paper: astro-ph/0512291

Date: Mon, 12 Dec 2005 19:19:49 GMT (74kb)

Title: Ultraviolet Radiation Constraints around the Circumstellar Habitable
Zones

Authors: Andrea P. Buccino, Guillermo A. Lemarchand, Pablo J. D. Mauas

Comments: 29 pages, 8 figures
\\
Ultraviolet radiation is known to inhibit photosynthesis, induce DNA
destruction and cause damage to a wide variety of proteins and lipids. In
particular, UV radiation between 200-300 nm becomes energetically very damaging to most of the terrestrial biological systems. On the other hand, UV radiation is usually considered one of the most important energy source on the primitive Earth for the synthesis of many biochemical compounds and, therefore, essential for several biogenesis processes. In this work, we use these properties of the UV radiation to define the bounderies of an ultraviolet habitable zone. We also analyze the evolution of the UV habitable zone during the main sequence stage of the star. We apply these criteria to study the UV habitable zone for those
extrasolar planetary systems that were observed by the International
Ultraviolet Explorer (IUE). We analyze the possibility that extrasolar planets
and moons could be suitable for life, according to the UV constrains presented
in this work and other accepted criteria of habitability (liquid water, orbital
stability, etc.).

\\ ( http://arXiv.org/abs/astro-ph/0512291 , 74kb)

------------------------------------------------------------------------------

\\
Paper: astro-ph/0512292

Date: Mon, 12 Dec 2005 14:46:55 GMT (56kb)

Title: Gas Flow Across Gaps in Protoplanetary Disks

Authors: Steve H. Lubow and Gennaro D'Angelo

Comments: 10 pages, 3 figures, 1 table. To appear in The Astrophysical Journal
\\
We analyze the gas accretion flow through a planet-produced gap in a
protoplanetary disk. We adopt the alpha disk model and ignore effects of
planetary migration. We develop a semi-analytic, one-dimensional model that
accounts for the effects of the planet as a mass sink and also carry out
two-dimensional hydrodynamical simulations of a planet embedded in a disk. The
predictions of the mass flow rate through the gap based on the semi-analytic
model generally agree with the hydrodynamical simulations at the 25% level.
Through these models, we are able to explore steady state disk structures and
over large spatial ranges. The presence of an accreting Jupiter-mass planet
significantly lowers the density of the disk within a region of several times
the planet's orbital radius. The mass flow rate across the gap (and onto the
central star) is typically 10% to 25% of the mass accretion rate outside the
orbit of the planet, for planet-to-star mass ratios that range from 5e-5 to
1e-3.

\\ ( http://arXiv.org/abs/astro-ph/0512292 , 56kb)

Posted by: Richard Trigaux Dec 14 2005, 11:40 AM

Posted by: edstrick Dec 14 2005, 12:12 PM

One thing I have not seen much discussion of, at least in scientifically literate public reporting, is the interplay between atmosphere column mass and habitabality. A planet at Mars distance from the sun with (arm waving number) 2 atmospheres surface pressure would have a stronger greenhouse than Earth and be more temperate than a 1 atmosphere pressure global Alaska world.

A relatively high mass planet with a dense atmosphere could orbit F type star and have a fairly well shielded surface, though it might end up in a runaway greenhouse too soon as the star brightened on the main sequence.

At the other end of star masses, a high mass terrestrial planet with thick atmosphere, if one can accrete near a red dwarf, would be protected by the thermal inertia of it's atmosphere from flare-star activity, and have much better dayside --> nightside heat transfer than a 1 atmosphere mass planet (since it's presumably tidally despun)

While humans might not tolerate a planet with say 5 atmospheres of nitrogen (nitrogen narcosis is not recommended), the "locals" that might evolve would have no problem.

Posted by: Richard Trigaux Dec 14 2005, 12:54 PM

One thing I have not seen much discussion of, at least in scientifically literate public reporting, is the interplay between atmosphere column mass and habitabality.  A planet at Mars distance from the sun with (arm waving number) 2 atmospheres surface pressure would have a stronger greenhouse than Earth and be more temperate than a 1 atmosphere pressure global Alaska world. 

A relatively high mass planet with a dense atmosphere could orbit F type star and have a fairly well shielded surface, though it might end up in a runaway greenhouse too soon as the star brightened on the main sequence.

At the other end of star masses, a high mass terrestrial planet with thick atmosphere, if one can accrete near a red dwarf, would be protected by the thermal inertia of it's atmosphere from flare-star activity, and have much better dayside --> nightside heat transfer than a 1 atmosphere mass planet (since it's presumably tidally despun)

While humans might not tolerate a planet with say 5 atmospheres of nitrogen (nitrogen narcosis is not recommended), the "locals" that might evolve would have no problem.

Posted by: ljk4-1 Dec 14 2005, 07:54 PM

Paper: astro-ph/0512221
Date: Thu, 8 Dec 2005 15:11:22 GMT (163kb)

Title: Abundance ratios of volatile vs. refractory elements in
planet-harbouring stars: hints of pollution?

Authors: A. Ecuvillon (1), G. Israelian (1), N. C. Santos (2,3), M. Mayor (3),
G. Gilli (1,4) ((1) IAC, Spain, (2) Observatorio Astronomico de Lisboa,
Portugal, (3) Observatoire de Geneve, Switzerland, (4) Dipartimento di
Astronomia, Universita di Padova, Italy)

Comments: 10 pages, 7 figures, accepted for publication in A&A. Figures with
higher resolution are available at www.iac.es/proyect/abuntest
\\
We present the [X/H] trends as function of the elemental condensation
temperature Tc in 88 planet host stars and in a volume-limited comparison
sample of 33 dwarfs without detected planetary companions. We gathered
homogeneous abundance results for many volatile and refractory elements
spanning a wide range of Tc, from a few dozens to several hundreds kelvin. We
investigate possible anomalous trends of planet hosts with respect to
comparison sample stars in order to detect evidence of possible pollution
events. No significant differences are found in the behaviour of stars with and
without planets. This result is in agreement with a ``primordial'' origin of
the metal excess in planet host stars. However, a subgroup of 5 planet host and
1 comparison sample stars stands out for having particularly high [X/H] vs. Tc
slopes.

\\ ( http://arXiv.org/abs/astro-ph/0512221 , 163kb)

------------------------------------------------------------------------------
\\
Paper: astro-ph/0512222
Date: Thu, 8 Dec 2005 15:16:52 GMT (42kb)

Title: Condensation temperature trends among stars with planets

Authors: Guillermo Gonzalez

Comments: 5 pages, 7 figures, MNRAS Letter in press
\\
Results from detailed spectroscopic analyses of stars hosting massive planets
are employed to search for trends between abundances and condensation
temperatures. The elements C, S, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni and
Zn are included in the analysis of 64 stars with planets and 33 comparison
stars. No significant trends are evident in the data. This null result suggests
that accretion of rocky material onto the photospheres of stars with planets is
not the primary explanation for their high metallicities. However, the
differences between the solar photospheric and meteoritic abundances do display
a weak but significant trend with condensation temperature. This suggests that
the metallicity of the sun's envelope has been enriched relative to its
interior by about 0.07 dex.

\\ ( http://arXiv.org/abs/astro-ph/0512222 , 42kb)

Posted by: ljk4-1 Dec 14 2005, 08:38 PM

Paper: astro-ph/0412356

replaced with revised version Tue, 13 Dec 2005 00:49:09 GMT (226kb)

Title: How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of
Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars

Authors: Daniel Grether (School of Physics, University of New South Wales) and
Charles H. Lineweaver (Planetary Science Institute, Research School of
Astronomy and Astrophysics & Research School of Earth Sciences, Australian
National University)

Comments: Conforms to version accepted by ApJ. 13 pages formatted with
emulateapj.cls

\\ ( http://arXiv.org/abs/astro-ph/0412356 , 226kb)


Paper: astro-ph/0512322
Date: Tue, 13 Dec 2005 13:03:32 GMT (71kb)

Title: Spectroscopic companions of very young brown dwarfs

Authors: Joergens Viki (Leiden Observatory)

Comments: Proceeding of ESO workshop 'Multiple Stars across the HRD' (Garching
2005). 6 pages, 4 figures
\\
I review here the results of the first RV survey for spectroscopic companions
to very young brown dwarfs (BDs) and (very) low-mass stars in the ChaI
star-forming cloud with UVES at the VLT. This survey studies the binary
fraction in an as yet unexplored domain not only in terms of primary masses
(substellar regime) and ages (a few Myr) but also in terms of companion masses
(sensitive down to planetary masses) and separations (< 1 AU). The UVES spectra
obtained so far hint at spectroscopic companions of a few Jupiter masses around
one BD and around one low-mass star (M4.5) with orbital periods of at least
several months. Furthermore, the data indicate a multiplicity fraction
consistent with field BDs and stellar binaries for periods < 100 days.

\\ ( http://arXiv.org/abs/astro-ph/0512322 , 71kb)

Posted by: David Dec 15 2005, 11:01 AM

Yes octopodes are bilaterals too, pardon my mistake. I was rather thinking to star fishes.

Posted by: Richard Trigaux Dec 15 2005, 01:33 PM

Surprising as it may seem, starfishes are bilaterians too!  Not only that, but the echinoderms are more closely related to vertebrates like us than to other bilaterians like molluscs and insects.  Starfish larvae are recognizably bilaterally symmetric, but as they mature they acquire the pentaradial symmetry characteristic of echinoderms; the radial symmetry is a secondary development, not shared by the common bilaterian ancestor.

Posted by: ljk4-1 Dec 15 2005, 04:26 PM

Paper: astro-ph/0512371

Date: Wed, 14 Dec 2005 18:29:41 GMT (49kb)

Title: Polycyclic Aromatic Hydrocarbons Orbiting HD 233517, an Evolved
Oxygen-Rich Red Giant

Authors: M. Jura (UCLA), J. Bohac, B. Sargent, W. J. Forrest, J. Green, D. M.
Watson (Rochester), G. C. Sloan (Cornell), F. Markwick-Kemper (Virginia), C.
H. Chen, J. Najita (NOAO)

Comments: 11 pages, 2 figures, ApJ Letters, in press
\\
We report spectra obtained with the Spitzer Space Telescope in the 5 to 35
micron range of HD 233517, an evolved K2 III giant with circumstellar dust. At
wavelengths longer than 13 microns, the flux is a smooth continuum that varies
approximately as frequency to the -5/3 power. For wavelengths shorter than 13
microns, although the star is oxygen-rich, PAH features produced by carbon-rich
species at 6.3 microns, 8.2 microns, 11.3 microns and 12.7 microns are detected
along with likely broad silicate emission near 20 microns. These results can be
explained if there is a passive, flared disk orbiting HD 233517. Our data
support the hypothesis that organic molecules in orbiting disks may be
synthesized in situ as well as being incorporated from the interstellar medium.

\\ ( http://arXiv.org/abs/astro-ph/0512371 , 49kb)

Posted by: ljk4-1 Dec 15 2005, 08:31 PM

Computer Security Expert Rejects Hacker Hypothesis

For Immediate Release

LITTLE FERRY, NJ.., 15 December 2005 -- A member of the grassroots, nonprofit SETI League has allayed fears expressed by some scientists, that malevolent signals from extraterrestrial civilizations could cripple Earth's computer networks. Responding to the so-called "SETI Hacker Hypothesis" articulated by particle physicist Richard A. Carrigan, Jr. of the Fermi National Laboratory, Canadian computer security expert Marcus Leech states "we test some of the elements of this hypothesis and find them to be unsupportable."

SETI science seeks evidence of advanced technological civilizations in space, primarily by monitoring electromagnetic emissions with optical and radio telescopes. Through the SETI@home experiment at the University of California, Berkeley, millions of personal computers worldwide have since 1999 been participating in distributed processing of data from one of those telescopes, the 305 meter dish in Arecibo, Puerto Rico. The SETI Hacker Hypothesis suggests that those computers could be at risk from malicious code deliberately sent Earthward by extraterrestrials. But in a recent paper available on The SETI League website at http://www.setileague.org/articles/hacker.pdf, Leech concludes that these fears are unfounded.

Carrigan's concerns were first voiced in a paper presented at a 2002 BioAstronomy conference, titled "The Ultimate Hacker: SETI signals may need to be decontaminated." Elements of that paper have recently resurfaced on the self-proclaimed nerd website SlashDot.org, been reported in the British newspaper The Guardian and elsewhere, and submitted to the prestigious scholarly journal Acta Astronautica. Carrigan states that "Biological contamination from space is a remote but recognized possibility. SETI signals might also contain harmful information." He argues for a decontamination process similar to that used when the first moon rocks were returned to Earth in 1969.

In response, Leech, formerly security area director for the Internet Engineering Task Force, makes the most generous assumptions possible in favor of the alleged ET hacker, and shows that such beings would be unable to trigger a buffer overflow, the known security flaw in computers most often exploited by terrestrial hackers. He allows that "while one cannot recommend a cavalier attitude with respect to software quality used by our SETI researchers, it's a near-certainty that computer viruses from outer space will not be one of the threats that need to be defended against."

"We conclude," states Leech, "with apologies to the film Independence Day, that SETI-hacker scenarios are only plausible within the fanciful confines of Hollywood, and then only when our ET hackers happen to be Macintosh ™ savvy."

Largely using radio telescopes and optical telescopes, SETI scientists seek to determine whether humankind is alone in the universe. Since Congress terminated NASA's SETI funding in 1993, The SETI League and other scientific groups have privatized the research. Amateur and professional scientists interested in participating in the search for intelligent alien life, and citizens wishing to help support it, should email join @ setileague.org, check the SETI League Web site at http://www.setileague.org/, send a fax to +1 (201) 641-1771, or contact The SETI League, Inc. membership hotline at +1 (800) TAU-SETI. Be sure to provide us with a postal address to which we will mail further information. The SETI League, Inc. is a membership-supported, non-profit [501©(3)], educational and scientific corporation dedicated to the scientific Search for Extra-Terrestrial Intelligence.

P.S. Tearsheets are always appreciated. Thank you.

-end-

--
H. Paul Shuch, Ph.D. Executive Director, The SETI League, Inc.
433 Liberty Street, PO Box 555, Little Ferry NJ 07643 USA
voice (201) 641-1770; fax (201) 641-1771; URL http://www.setileague.org
email work: n6tx@setileague.org; home: drseti@cal.berkeley.edu

Posted by: David Dec 16 2005, 02:59 AM

Ahem ahem

there must be some beings who are not bilateralians, at last? 

Posted by: Richard Trigaux Dec 16 2005, 08:40 AM

That pretty much sums it up for metazoans; the next closest related group of macroscopic organisms are the fungi.    I have some doubts -- small ones -- about the ability of fungi-like organisms to create a space-faring civilization, but I am willing to be convinced otherwise. 

Posted by: ljk4-1 Dec 19 2005, 06:08 PM

Paper: astro-ph/0512445

Date: Fri, 16 Dec 2005 17:56:49 GMT (76kb)

Title: Planetary catastrophe risks cannot generally be inferred from the
Earth's formation date

Authors: Adrian Kent (Department of Applied Mathematics and Theoretical
Physics, University of Cambridge)

Comments: 2 pages
\\
Tegmark and Bostrom's provocative analysis of the chances of a "doomsday
catastrophe" [Nature 438, 754 (2005)] sets out an interesting idea, but
unfortunately contains a fundamental error which invalidates their conclusions.
The essential problem with their argument can be seen by considering the
assertion that "if [planet-destroying] catastrophes were very frequent, then
almost all intelligent civilisations would have arisen much earlier than ours".
This does not follow from Tegmark and Bostrom's assumptions.

\\ ( http://arXiv.org/abs/astro-ph/0512445 , 0kb)

Posted by: ljk4-1 Dec 19 2005, 08:11 PM

MONDAY, DECEMBER 19, 2005 - NGC

Naked Science: "Birth of the Earth" at 9P et/pt

How did Earth evolve to support such a diversity of living creatures,
including humans, requiring special living conditions to survive? An
imaginary "human" time traveler takes us on a journey back to the
moment our solar system was born.

Watch a preview.

http://ng.chtah.com/a/tBDpv6HASJ4TXAbRKOPAOOv6R.ASJ-RO8d/ngs2


Naked Science: "Super Volcano" at 10P et/pt

A super volcano explosion is a million times stronger than the
atomic bombing of Hiroshima. Scientists have discovered an active
super volcano under Yellowstone National Park. What would happen
if it erupted? Could the United States survive?

Posted by: tty Dec 19 2005, 11:28 PM

fungi? Yes they can. At a similar state of evolution, we were not better. Given equal chances, they may have evolved in intelligent beings.

Seriously, what, I think, gave the advantage to bilateralians is not the bilateral symmetry by itself, it is a set of innovations the other were deprived, such as nervous cells, or the coelome (sorry this is the latin name I don't know in english) or closed inner body cavity which allowed all the building of further evolution. The lombrics can move thank to coelomes (one per ring), and we still have three body cavities (or lombric-like rings) separated by muscles: chest, belly, and a smaller perinear cavity.  Fungi seriously lack such structures, and corals have an open boby cavity for feeding (the opening serving ans both mouth and anus).

These body structures were first coded by a series of adjacent genes, called homeobox, each one coding for a body segment, and controling the growth of each segment. Further evolution complexified this scheme, but without altering the basic structure. It is the very unlikely appearance of such a complex structure which took many time and was the real breakthrough which allowed bilateralians to be the first. As such an event is rare, it does not happens often, only once in Earth history, and it is likely not to happen again, as the bilateralians now hamper any further evolution of the other clades.

beings like fungi are multicellular, but they don't have a homeobox-like system, and other system such as specialized cells. This allow them to grow rapidly, but with only simple structures.

Sime dates for Earth history:
-multicellular beings are traced from -600 millions years and likely existed 1 billion years ago
-bilateralians are known since 600 millions years only.

Posted by: Richard Trigaux Dec 20 2005, 10:09 AM

Actually Hox genes are not specific to Bilateria since Cnidarians also have them, though only two each (homologous to the anterior and posterior Hox groups of e. g. arthropods). Sponges do lack Hox genes.

Multicellular organisms (algae) are known bact to at least 1200 mya (million years ago).  Bilateria are known back to about 600 mya (earliest Edicaran faunas), but molecular data suggest they are at least 100 my older.  This incidentally means that they originated at about the time of the extreme Neoproterozoic glaciations which may have turned Earth into a "snowball", or nearly so. The mass extinction these must have caused may have "made way" for new life-forms, including ultimately us.

tty

Posted by: Richard Trigaux Dec 20 2005, 10:31 AM

Paper: astro-ph/0512445

Date: Fri, 16 Dec 2005 17:56:49 GMT  (76kb)

Title: Planetary catastrophe risks cannot generally be inferred from the
  Earth's formation date

Authors: Adrian Kent (Department of Applied Mathematics and Theoretical
  Physics, University of Cambridge)

Comments: 2 pages
\\
  Tegmark and Bostrom's provocative analysis of the chances of a "doomsday
catastrophe" [Nature 438, 754 (2005)] sets out an interesting idea, but
unfortunately contains a fundamental error which invalidates their conclusions.
The essential problem with their argument can be seen by considering the
assertion that "if [planet-destroying] catastrophes were very frequent, then
almost all intelligent civilisations would have arisen much earlier than ours".
This does not follow from Tegmark and Bostrom's assumptions.

\\ ( http://arXiv.org/abs/astro-ph/0512445 ,  0kb)

Posted by: ljk4-1 Dec 21 2005, 05:04 AM

Partial Ingredients for DNA and Protein Found Around Star

NASA’s Spitzer Space Telescope has discovered some of life’s most basic ingredients in the dust swirling around a young star. The ingredients – gaseous precursors to DNA and protein – were detected in the star’s terrestrial planet zone, a region where rocky planets such as Earth are thought to be born.

The findings represent the first time that these gases, called acetylene and hydrogen cyanide, have been found in a terrestrial planet zone outside of our own.

"This infant system might look a lot like ours did billions of years ago, before life arose on Earth," said Fred Lahuis of Leiden Observatory in the Netherlands and the Dutch space research institute called SRON. Lahuis is lead author of a paper to be published in the Jan. 10 issue of the Astrophysical Journal Letters.

http://www.spitzer.caltech.edu/Media/releases/ssc2005-26/release.shtml

Posted by: deglr6328 Dec 21 2005, 06:02 AM

I think its JUST a bit of a stretch to say that partial ingredients for DNA and protein were found when really all they found was HCN and C2H2. Almost like saying "environment suitable for polar bear habitat found on Enceladus"! Interesting nonetheless though.

Posted by: Richard Trigaux Dec 21 2005, 08:38 AM

I think its JUST a bit of a stretch to say that partial ingredients for DNA and protein were found when really all they found was HCN and C2H2. Almost like saying "environment suitable for polar bear habitat found on Enceladus"! Interesting nonetheless though.

Posted by: Richard Trigaux Dec 21 2005, 09:07 AM

Back to the idea of gamma ray bursts (GRB) able to sterilize a whole galaxy.

First, even if GRBs are really dangerous, I have some doubts that they are really able to sterilize a whole galaxy.

Second, I note that GRBs occured in a distant past, perhaps at an epoch where the metallicity of stars was lower. As far as I know, the most recent GRBs are 3 billion years old, and the peak activity was 10 billions years ago. And they are not as numerous as we can think. (If we assume one detection per day, and 130 billion galaxies, that makes about 2.8 GRBs per billion years in a given galaxy, 10 billion years ago)

So we can figure this out: 10 billion years ago, GRBs were very numerous, and, if they were really able to sterilize a galaxy, this happened every 360 million years in average, much too short a time to allow for evolved life to appear.
But the activity of GRBs gradually subsided, and is quasi-zero today. So we may find most galaxies where there was no GRBs since 3, or 5, see 7 billion years.

Applied to our galaxy, this makes about the age of the Earth, and an elegant solution to the black sky paradox (life is expected to appear on many planets, but we yet detected no evolved civilizations): we would be amont the firsts to appear.

Places which are expected to have stopped any GRB activity for longer than our galaxy would be giant elliptic galaxies like Virgo. This is the best place to search for giant Type III civilizations (After kardanchev a Type III civilization is using the energy of its whole galaxy). So this is the place where we can more expect things like Dyson spheres, engineered stars, etc (if any such things can exist, but this is not what seems the most likely to me)

Posted by: ljk4-1 Dec 21 2005, 05:52 PM

On December 15 former Senator William Proxmire of Wisconsin died at the age of 90. Proxmire was no friend of the space program, and in 1979 he gave one his famous “golden fleece” awards for wasteful government spending to NASA for its research in the search for extraterrestrial intelligence (SETI). A few years later he was instrumental in stopping government support for SETI.

But Proxmire also provided The Planetary Society with one of its greatest victories, and consequently earned the respect of Carl Sagan and the organization for his willingness to listen.

The rest is here:

http://planetary.org/news/2005/1216_Society_Marks_Passing_of_SETI_Critic.html

Posted by: Richard Trigaux Dec 21 2005, 06:07 PM

On December 15 former Senator William Proxmire of Wisconsin died at the age of 90.   Proxmire was no friend of the space program, and in 1979 he gave one his famous “golden fleece” awards for wasteful government spending to NASA for its research in the search for extraterrestrial intelligence (SETI). A few years later he was instrumental in stopping government support for SETI.

But Proxmire also provided The Planetary Society with one of its greatest victories, and consequently earned the respect of Carl Sagan and the organization for his willingness to listen.

The rest is here:

http://planetary.org/news/2005/1216_Society_Marks_Passing_of_SETI_Critic.html

Posted by: ljk4-1 Dec 22 2005, 05:18 PM

Astrophysics, abstract
astro-ph/0512204

From: Max Tegmark [view email]

Date (v1): Thu, 8 Dec 2005 05:17:15 GMT (21kb)

Date (revised v2): Wed, 21 Dec 2005 14:28:48 GMT (23kb)

How unlikely is a doomsday catastrophe?

Authors: Max Tegmark (MIT), Nick Bostrom (Oxford)

Comments: Substantially expanded discussion to better explain key argument. 4 pages, 1 fig

Numerous Earth-destroying doomsday scenarios have recently been analyzed, including breakdown of a metastable vacuum state and planetary destruction triggered by a "strangelet'' or microscopic black hole. We point out that many previous bounds on their frequency give a false sense of security: one cannot infer that such events are rare from the the fact that Earth has survived for so long, because observers are by definition in places lucky enough to have avoided destruction. We derive a new upper bound of one per 10^9 years (99.9% c.l.) on the exogenous terminal catastrophe rate that is free of such selection bias, using planetary age distributions and the relatively late formation time of Earth.

http://arxiv.org/abs/astro-ph/0512204

Posted by: ljk4-1 Dec 23 2005, 04:01 PM

Paper: astro-ph/0512561

Date: Thu, 22 Dec 2005 13:45:36 GMT (241kb)

Title: Photodissociation of organic molecules in star-forming regions II:
Acetic acid

Authors: S. Pilling (1 and 2), A. C. F. Santos (3) and H. M. Boechat-Roberty
(1) ((1) OV-UFRJ, (2) IQ-UFRJ, (3) IF-UFRJ)

Comments: Comments: 8 pages, 5 figures, 3 tables. Accepted to be printed in A&A
\\
Fragments from organic molecule dissociation (such as reactive ions and
radicals) can form interstellar complex molecules like amino acids. The goal of
this work is to experimentally study photoionization and photodissociation
processes of acetic acid (CH$_3$COOH), a glycine (NH$_2$CH$_2$COOH) precursor
molecule, by soft X-ray photons. The measurements were taken at the Brazilian
Synchrotron Light Laboratory (LNLS), employing soft X-ray photons from a
toroidal grating monochromator (TGM) beamline (100 - 310 eV). Mass spectra were
obtained using the photoelectron photoion coincidence (PEPICO) method. Kinetic
energy distribution and abundances for each ionic fragment have been obtained
from the analysis of the corresponding peak shapes in the mass spectra.
Absolute photoionization and photodissociation cross sections were also
determined. We have found, among the channels leading to ionization, that only
4-6% of CH$_3$COOH survive the strong ionization field. CH$_3$CO$^+$, COOH$^+$
and CH$_3^+$ ions are the main fragments, and the presence of the former may
indicate that the production-destruction process of acetic acid in hot
molecular cores (HMCs) could decrease the H$_2$O abundance since the net result
of this process converts H$_2$O into OH + H$^+$. The COOH$^+$ ion plays an
important role in ion-molecule reactions to form large biomolecules like
glycine.

\\ ( http://arXiv.org/abs/astro-ph/0512561 , 241kb)

------------------------------------------------------------------------------

Paper: astro-ph/0512563
Date: Thu, 22 Dec 2005 14:11:29 GMT (946kb)

Title: Molecular gas in the Andromeda galaxy

Authors: Ch. Nieten (1), N. Neininger (1,2,3), M. Guelin (3), H. Ungerechts
(4), R. Lucas (3), E. M. Berkhuijsen (1), R. Beck (1), R. Wielebinski (1)
((1) MPI fuer Radioastronomie, Bonn, Germany, (2) Radioastronomisches
Institut, Univ. Bonn, Germany, (3) IRAM, Grenoble, France, (4) IRAM, Granada,
Spain)

Comments: 21 pages, 16 figures. Accepted for publication in A&A
\\
We present a new 12CO(J=1-0)-line survey of the Andromeda galaxy, M31,
covering the bright disk with the highest resolution to date (85 pc along the
major axis), observed On-the-Fly (in italics) with the IRAM 30-m telescope. We
discuss the distribution of the CO emission and compare it with the
distributions of HI and emission from cold dust traced at 175mum. Our main
results are: 1. Most of the CO emission comes from the radial range R=3-16 kpc,
but peaks near R=10 kpc. The emission is con- centrated in narrow, arm-like
filaments defining two spiral arms with pitch angles of 7d-8d. The average
arm-interarm brightness ratio along the western arms reaches 20 compared to 4
for HI. 2. For a constant conversion factor Xco, the molecular fraction of the
neutral gas is enhanced in the arms and decreases radially. The apparent
gas-to-dust ratios N(HI)/I175 and (N(HI)+2N(H2))/I175 increase by a factor of
20 between the centre and R=14 kpc, whereas the ratio 2N(H2)/I175 only
increases by a factor of 4. Implications of these gradients are discussed. In
the range R=8-14 kpc total gas and cold dust are well correlated; molecular gas
is better correlated with cold dust than atomic gas.

\\ ( http://arXiv.org/abs/astro-ph/0512563 , 946kb)

Posted by: ljk4-1 Dec 26 2005, 06:58 PM

Paper: astro-ph/0512589
Date: Fri, 23 Dec 2005 05:42:54 GMT (218kb)

Title: A CH3CN and HCO+ survey towards southern methanol masers associated with
star formation

Authors: C. R. Purcell, R. Balasubramanyam, M. G. Burton, A. J. Walsh, V.
Minier, M. R. Hunt-Cunningham, L. L. Kedziora-Chudczer, S. N. Longmore, T.
Hill, I. Bains, P. J. Barnes, A. L. Busfield, P. Calisse, N. H. M. Crighton,
S. J. Curran, T. M. Davis, J. T. Dempsey, G. Derragopian, B. Fulton, M. G.
Hidas, M. G. Hoare, J.-K. Lee, E. F. Ladd, S. L. Lumsden, T. J. T. Moore, M.
T. Murphy, R. D. Oudmaijer, M. B. Pracy, J. Rathborne, S. Robertson, A. S. B.
Schultz, J. Shobbrook, P. A. Sparks, J. Storey, T. Travouillion

Comments: 29 pages, 16 figures. Accepted for publication in MNRAS. For
associated online figures please see

http://www.phys.unsw.edu.au/~crp/papers/cpurcell_2005_online.pdf

\\
We present the initial results of a 3-mm spectral line survey towards 83
methanol maser selected massive star-forming regions. Here we report
observations of the J=5-4 and 6-5 rotational transitions of methyl cyanide
(CH3CN) and the J=1-0 transition of HCO+and H13CO+.

CH3CN emission is detected in 58 sources (70 %) of our sample). We estimate
the temperature and column density for 37 of these using the rotational diagram
method. The temperatures we derive range from 28-166 K, and are lower than
previously reported temperatures, derived from higher J transitions. We find
that CH3CN is brighter and more commonly detected towards ultra-compact HII
(UCHII) regions than towards isolated maser sources. Detection of CH3CN towards
isolated maser sources strongly suggests that these objects are internally
heated and that CH3CN is excited prior to the UCHII phase of massive
star-formation.

HCO+ is detected towards 82 sources (99 % of our sample), many of which
exhibit asymmetric line profiles compared to H13CO+. Skewed profiles are
indicative of inward or outward motions, however, we find approximately equal
numbers of red and blue-skewed profiles among all classes. Column densities are
derived from an analysis of the HCO+ and H13CO+ line profiles.

80 sources have mid-infrared counterparts: 68 seen in emission and 12 seen in
absorption as `dark clouds'. Seven of the twelve dark clouds exhibit asymmetric
HCO+ profiles, six of which are skewed to the blue, indicating infalling
motions. CH3CN is also common in dark clouds, where it has a 90 % detection
rate.

\\ ( http://arXiv.org/abs/astro-ph/0512589 , 218kb)

Posted by: ljk4-1 Dec 30 2005, 06:17 PM

Pulsars as Beacons for SETI

Abstract: This paper proposes that pulsars can serve as beacons for the discovery of and communication with extraterrestrials. The motivation for the communication strategy proposed is discussed in detail, along with relevant astrophysical considerations.

It is shown that millisecond pulsars have characteristics and a distribution in space that make it possible to envisage communication being targeted towards and away from habstars (as defined by Turnbull & Tarter) aligned with pulsars in a
specified way. Lists of candidate habstars and their pulsar alignments are included for those wishing to conduct searches using the strategy described.

http://www.cs.bham.ac.uk/~whe/SETIPaper.pdf

The author of the above paper received 30 hours of time on the Arecibo Radio Telescope to gather data for his SETI concept. You can read the proposal here:

http://www.cs.bham.ac.uk/~whe/AOproposal.pdf

More information here:

http://www.cs.bham.ac.uk/~whe/CETI.html

Posted by: ljk4-1 Jan 4 2006, 07:29 PM

Paper: astro-ph/0507422

From: Jonathan J. Fortney [view email]

Date (v1): Mon, 18 Jul 2005 21:49:23 GMT (134kb)
Date (revised v2): Tue, 3 Jan 2006 19:32:19 GMT (224kb)

replaced with revised version Tue, 3 Jan 2006 19:32:19 GMT (224kb)

Title: Atmosphere, Interior, and Evolution of the Metal-Rich Transiting Planet
HD 149026b

Authors: J. J. Fortney, D. Saumon, M. S. Marley, K. Lodders, R. S. Freedman

Comments: Accepted to the Astrophysical Journal. 18 pages, including 10
figures. New section on the atmosphere of planet HD 189733b. Enhanced
discussion of atmospheric Ti chemistry and core mass for HD 149026b

We investigate the atmosphere and interior of the new transiting planet HD 149026b, which appears to be very rich in heavy elements. We first compute model atmospheres at metallicities ranging from solar to ten times solar, and show how for cases with high metallicity or inefficient redistribution of energy from the day side, the planet may develop a hot stratosphere due to absorption of stellar flux by TiO and VO. The spectra predicted by these models are very different than cooler atmosphere models without stratospheres. The spectral effects are potentially detectable with the Spitzer Space Telescope. In addition the models with hot stratospheres lead to a large limb brightening, rather than darkening. We compare the atmosphere of HD 149026b to other well-known transiting planets, including the recently discovered HD 189733b, which we show have planet-to-star flux ratios twice that of HD 209458 and TrES-1. The methane abundance in the atmosphere of HD 189733b is a sensitive indicator of atmospheric temperature and metallicity and can be constrained with Spitzer IRAC observations. We then turn to interior studies of HD 149026b and use a grid of self-consistent model atmospheres and high-pressure equations of state for all components to compute thermal evolution models of the planet. We estimate that the mass of heavy elements within the planet is in the range of 60 to 93 M_earth. Finally, we discuss trends in the radii of transiting planets with metallicity in light of this new member of the class.

\\ ( http://arXiv.org/abs/astro-ph/0507422 , 224kb)

Posted by: ljk4-1 Jan 6 2006, 08:09 PM

This is from the latest Sky & Telescope News Bulletin, of all places.

LOOKING FOR A CREATOR'S CALLING CARD

If our universe was purposefully created -- perhaps by a deity or an
advanced civilization in another universe -- could the creator have left a
calling card in the microwave background?

The idea is not as crazy as it seems. Cosmologists such as Andre Linde
(Stanford University) and Alan Guth (MIT) have speculated that an advanced
civilization could, in principle, cook up a new universe in a lab by
concentrating huge quantities of energy into a tiny volume of space....

In a paper posted on astro-ph, physicists Stephen Hsu (University of
Oregon) and Anthony Zee (University of California, Santa Barbara) come up
with an alternative idea: astronomers could look for an artificial message
from the creator in the cosmic microwave background (CMB) -- the afterglow
of the Big Bang....

http://SkyandTelescope.com/news/article_1647_1.asp

Posted by: ljk4-1 Jan 7 2006, 08:34 PM

Active Assessment of Active SETI

by H. Paul Shuch, Ph.D.

Almost since its inception nearly half a century ago, SETI science has seen its supporters wage a running battle over the question of transmissions from Earth. Deliberate transmission of signals into space, sometimes called Active SETI, is justified by its proponents on the grounds of reciprocity. That is, some argue, we cannot in good conscience search for signals which we would hope other civilizations might choose to beam our way, if we ourselves are not willing to transmit such signals from Earth. The counter-argument involves the safety, and some would say the very survival, of our planet.

Critics to Active SETI point out the dangers of shouting in the jungle. Radio amateurs in support of Active SETI counter that (1) the cat is already out of the bag, as we have been inadvertently transmitting to the stars for a century or so, and (2) if everybody's listening and nobody calls CQ, the bands will appear dead to all concerned.

http://www.setileague.org/editor/sanmarin.htm

Posted by: Richard Trigaux Jan 8 2006, 05:56 PM

The counter-argument involves the safety, and some would say the very survival, of our planet.

Critics to Active SETI point out the dangers of shouting in the jungle. Radio amateurs in support of Active SETI counter that (1) the cat is already out of the bag, as we have been inadvertently transmitting to the stars for a century or so, and (2) if everybody's listening and nobody calls CQ, the bands will appear dead to all concerned.

http://www.setileague.org/editor/sanmarin.htm

Posted by: ljk4-1 Jan 10 2006, 03:44 AM

My bets are on missionaries and/or there's a major galactic construction project going on, and we're the rabbit den that will happen to be in the way.

Posted by: ljk4-1 Jan 10 2006, 03:20 PM

Astrophysics, abstract
astro-ph/0601166

From: Susanne Pfalzner Dr [view email]

Date: Mon, 9 Jan 2006 08:08:17 GMT (353kb)

Encounter-Triggered Disc Mass Loss in the ONC

Authors: C. Olczak, S.Pfalzner, R.Spurzem

Comments: 32 pages, 12 figures, 3 tables. accepted by ApJ

The relevance of encounters on the destruction of protoplanetary discs in the Orion Nebula Cluster (ONC) is investigated by combining two different types of numerical simulation. First, star-cluster simulations are performed to model the stellar dynamics of the ONC, the results of which are used to investigate the frequency of encounters, the mass ratio and separation of the stars involved, and the eccentricity of the encounter orbits. The results show that interactions that could influence the star-surrounding disc are more frequent than previously assumed in the core of the ONC, the so-called Trapezium cluster. Second, a parameter study of star-disc encounters is performed to determine the upper limits of the mass loss of the discs in encounters. For simulation times of $\sim$ 1-2 Myr (the likely age of the ONC) the results show that gravitational interaction might account for a significant disc mass loss in dense clusters. Disc destruction is dominated by encounters with high-mass stars, especially in the Trapezium cluster, where the fraction of discs destroyed due to stellar encounters can reach 10-15%. These estimates are in accord with observations of (Lada et al. 2000) who determined a stellar disc fraction of 80-85%. Thus, it is shown that in the ONC - a typical star-forming region - stellar encounters do have a significant effect on the mass of protoplanetary discs and thus affect the formation of planetary systems.

http://arxiv.org/abs/astro-ph/0601166

Posted by: Richard Trigaux Jan 10 2006, 06:46 PM

Astrophysics, abstract
astro-ph/0601166

From: Susanne Pfalzner Dr [view email]

Date: Mon, 9 Jan 2006 08:08:17 GMT (353kb)

Encounter-Triggered Disc Mass Loss in the ONC

Authors: C. Olczak, S.Pfalzner, R.Spurzem

Comments: 32 pages, 12 figures, 3 tables. accepted by ApJ

The relevance of encounters on the destruction of protoplanetary discs in the Orion Nebula Cluster (ONC) is investigated by combining two different types of numerical simulation. First, star-cluster simulations are performed to model the stellar dynamics of the ONC, the results of which are used to investigate the frequency of encounters, the mass ratio and separation of the stars involved, and the eccentricity of the encounter orbits. The results show that interactions that could influence the star-surrounding disc are more frequent than previously assumed in the core of the ONC, the so-called Trapezium cluster. Second, a parameter study of star-disc encounters is performed to determine the upper limits of the mass loss of the discs in encounters. For simulation times of $\sim$ 1-2 Myr (the likely age of the ONC) the results show that gravitational interaction might account for a significant disc mass loss in dense clusters. Disc destruction is dominated by encounters with high-mass stars, especially in the Trapezium cluster, where the fraction of discs destroyed due to stellar encounters can reach 10-15%. These estimates are in accord with observations of (Lada et al. 2000) who determined a stellar disc fraction of 80-85%. Thus, it is shown that in the ONC - a typical star-forming region - stellar encounters do have a significant effect on the mass of protoplanetary discs and thus affect the formation of planetary systems.

http://arxiv.org/abs/astro-ph/0601166

Posted by: ljk4-1 Jan 12 2006, 08:14 PM

Transmitting to One Million Worlds

http://www.space.com/searchforlife/060112_shostak_transmit.html

SETI researchers have typically looked at any particular star system (at a given
frequency) for only a few minutes, at most. But what are the chances that an
alien signal has been sent our way just at the right moment to splash upon our
antennas during that brief interval?


Worlds With Multiple Suns Abundant

http://www.space.com/scienceastronomy/060112_binarystar_planets.html

Two new studies suggest that planet formation around multiple star systems may
be more common than previously thought.

Posted by: ljk4-1 Jan 12 2006, 09:13 PM

PLANET FINDERS DISCOVER NEW WORLD WITH FAST DEVICE
--------------------------------------------------

Astronomers have discovered a planet orbiting a very young star nearly 100
light years away using a relatively small, publicly accessible telescope
turbocharged with a new planet-finding instrument.

The feat suggests that astronomers have found a way to dramatically
accelerate the pace of the hunt for planets outside our solar system.

http://spaceflightnow.com/news/n0601/11planet/


POSSIBLE COMET DUST FOUND AROUND DEAD STAR
------------------------------------------

NASA's Spitzer Space Telescope has spotted what may be comet dust
sprinkled around a white dwarf star that died approximately 500 million
years ago. The findings suggest the star, which most likely consumed its
inner planets, is still orbited by a ring of surviving comets and possibly
outer planets.

http://spaceflightnow.com/news/n0601/11cometdust/

Posted by: Myran Jan 13 2006, 10:19 PM

The suggestions put forth by Mr Richard Trigaux are mostly interesting possibilities, and I agree that the cost for interstellar flight -even for one extremely advanced civilization- would be so high that it possibly would take some kind of 'grand idea' of one kind or other before they would undertake and well open the wallet for the tremendous cost.

But I would be hard pressed to accept the idea of any kind of civilization that would mine minerals in one stellar system and then ship the metals over interstellar distances.
There might be need for mining for one species that travel between the stars, perhaps for repairing the ship or possibly replace eroded radiation shields. But that would of cource be rather limited.

Posted by: ljk4-1 Jan 13 2006, 10:37 PM

The suggestions put forth by Mr Richard Trigaux are mostly interesting possibilities, and I agree that the cost for interstellar flight -even for one extremely advanced civilization- would be so high that it possibly would take some kind of 'grand idea' of one kind or other before they would undertake and well open the wallet for the tremendous cost.

But I would be hard pressed to accept the idea of any kind of civilization that would mine minerals in one stellar system and then ship the metals over interstellar distances.
There might be need for mining for one species that travel between the stars, perhaps for repairing the ship or possibly replace eroded radiation shields. But that would of cource be rather limited.
Galactic construction project? You placed your bets on the arrival of the Vogon construction fleet? 

Posted by: Richard Trigaux Jan 14 2006, 09:41 AM

But I would be hard pressed to accept the idea of any kind of civilization that would mine minerals in one stellar system and then ship the metals over interstellar distances.
There might be need for mining for one species that travel between the stars, perhaps for repairing the ship or possibly replace eroded radiation shields. But that would of cource be rather limited.

Posted by: Myran Jan 14 2006, 11:12 AM

Response to Richard Trigaux: I agree fully, my point was that interstellar flight would be a major task even for one really advanced spacfaring race/world.
So it was in response to you mentioning the 'need of mineral resources' that I intended to say that its quite unlikely but not impossible. And that any mining any aliens would do would rather be for secondary reasons.

There are some other materials suggested for a meteroite/radiation shield, one of them are to have a disk of beryllium flying a short distance ahead of a interstellar craft. But yes water could be used also, I think that was the idea in the book 'Songs from distant Earh' by Arthur C. Clarke and they indeed had to make a pitstop after their disk had been hit with something loosing most of its mass.

ljk4-1 said:

"As for one reason to travel interstellar distances: Leaving a star system where the sun is going terminal or the planets are no longer habitable."

Yes racial survival would of course put pressure on any race/species/entity, if any such develop (or even could) on a planet around one class A or F star they might be jumpstarted into becoming one interstellar society. That would of course also be something that would fit under my 'Grand idea' since spaceflight in that case would be a race for survival. Then we have the case of Homo Sapiens who are making their own planet inhabitable as we communicate here. I live in the arctic and havnt seen a normal winter for the last ten years. But im diverting from the subject and its too depressing to think about in any case.

Posted by: David Jan 14 2006, 02:02 PM

Transmitting to One Million Worlds

SETI researchers have typically looked at any particular star system (at a given
frequency) for only a few minutes, at most. But what are the chances that an
alien signal has been sent our way just at the right moment to splash upon our
antennas during that brief interval?

Posted by: ljk4-1 Jan 15 2006, 12:32 AM

Sister Society Issues Call for Papers

For more information contact: Dr. H. Paul Shuch, Executive Director

(201) 641-1770, or email info @ setileague.org

For Immediate Release

LITTLE FERRY, NJ.., January 2006 -- The Society of Amateur Radio Astronomers (SARA), a SETI League Affiliate Society that represents several hundred amateur radio astronomers around the world, hereby solicits papers for presentation at its 2006 Annual Meeting, to be held June 18-21, 2006, at the National Radio Astronomy Observatory (NRAO), Green Bank WV. Papers on radio astronomy hardware, software, education, research strategies, and philosophy are welcome. Although the annual Green Bank meeting is, strictly speaking, a SARA event, this year SETI League members have been invited to participate.

H. Paul Shuch, The SETI League's volunteer executive director, also serves as SARA vice president. In that capacity, he is coordinating this joint technical meeting. SARA members, SETI League members, or supporters wishing to present a paper should email a letter of intent, including a proposed title and informal abstract or outline (not to exceed 100 words) to Dr. Shuch at vicepres @ radio-astronomy.org, no later than 1 March 2006. Be sure to include your full name, affiliation, postal address, and email address, and indicate your willingness to attend the conference to present your paper. Submitters will receive an email response, typically within one week, along with a request to proceed to the next stage, if the proposal is consistent with the planned program.

A formal Proceedings will be published in conjunction with this Meeting. Papers will be peer-reviewed by a panel of SARA members with appropriate professional expertise and academic credentials. First-draft manuscripts must be received no later than 1 April 2006, with feedback, acceptance, or rejection emails to be sent within two weeks thereafter. Upon final editing of accepted papers, camera-ready copy will be due not later than 1 May 2006. Due to printer's deadlines, manuscripts received after that deadline will not make it into the Proceedings. Instructions for preparation of final manuscripts will be emailed to the authors of all accepted papers.

At its 2006 gathering, SARA members will be celebrating the club's 25th Anniversary. SETI League members in particular are encouraged to participate in this landmark meeting by presenting their work for the benefit of the two sister societies. Further information about SARA can be found on their website, radio-astronomy.org.

Largely using radio telescopes and optical telescopes, SETI scientists seek to determine whether humankind is alone in the universe. Since Congress terminated NASA's SETI funding in 1993, The SETI League and other scientific groups have privatized the research. Amateur and professional scientists interested in participating in the search for intelligent alien life, and citizens wishing to help support it, should email join @ setileague.org, check the SETI League Web site at http://www.setileague.org/, send a fax to +1 (201) 641-1771, or contact The SETI League, Inc. membership hotline at +1 (800) TAU-SETI. Be sure to provide us with a postal address to which we will mail further information. The SETI League, Inc. is a membership-supported, non-profit [501©(3)], educational and scientific corporation dedicated to the scientific Search for Extra-Terrestrial Intelligence.

P.S. Tearsheets are always appreciated. Thank you.

-end-

--
H. Paul Shuch, Ph.D. Executive Director, The SETI League, Inc.
433 Liberty Street, PO Box 555, Little Ferry NJ 07643 USA
voice (201) 641-1770; fax (201) 641-1771; URL http://www.setileague.org
email work: n6tx@setileague.org; home: drseti@cal.berkeley.edu

"We Know We're Not Alone!"

Posted by: ljk4-1 Jan 16 2006, 09:47 PM

The suggestions put forth by Mr Richard Trigaux are mostly interesting possibilities, and I agree that the cost for interstellar flight -even for one extremely advanced civilization- would be so high that it possibly would take some kind of 'grand idea' of one kind or other before they would undertake and well open the wallet for the tremendous cost.

But I would be hard pressed to accept the idea of any kind of civilization that would mine minerals in one stellar system and then ship the metals over interstellar distances.
There might be need for mining for one species that travel between the stars, perhaps for repairing the ship or possibly replace eroded radiation shields. But that would of cource be rather limited.
Galactic construction project? You placed your bets on the arrival of the Vogon construction fleet? 

 TheProject.pdf ( 645.8K ) : 5858

Posted by: ljk4-1 Jan 18 2006, 09:13 PM

Paper: astro-ph/0601356
Date: Tue, 17 Jan 2006 02:18:41 GMT (947kb)

Title: Introduction: Paleoheliosphere versus PaleoLISM

Authors: Priscilla C. Frisch

Comments: The article will appear in the book "Solar Journey: The Significance
of Our Galactic Environment for the Heliosphere and Earth", Springer, in
press (2006), editor P. C. Frisch
\\
Speculations that encounters with interstellar clouds modify the terrestrial
climate have appeared in the scientific literature for over 85 years. This
article introduces a series of articles that seek to give substance to these
speculations by examining the exact mechanisms that link the pressure and
composition of the interstellar medium surrounding the Sun to the physical
properties of the inner heliosphere at the Earth.

\\ ( http://arXiv.org/abs/astro-ph/0601356 , 947kb)

------------------------------------------------------------------------------

Paper: astro-ph/0601359
Date: Tue, 17 Jan 2006 03:30:06 GMT (848kb)

Title: Short-term Variations in the Galactic Environment of the Sun

Authors: Priscilla C. Frisch and Jonathan D. Slavin

Comments: The article will appear in the book "Solar Journey: The Significance
of Our Galactic Environment for the Heliosphere and Earth", Springer, in
press (2006), editor P. C. Frisch
\\
The galactic environment of the Sun varies over short timescales as the Sun
and interstellar clouds travel through space. Small variations in the dynamics,
ionization, density, and magnetic field strength of the interstellar medium
(ISM) surrounding the Sun yield pronounced changes in the heliosphere. We
discuss essential information required to understand short-term variations in
the galactic environment of the Sun, including the distribution and radiative
transfer properties of nearby ISM, and variations in the boundary conditions of
the heliosphere as the Sun traverses clouds. The most predictable transitions
are when the Sun emerged from the Local Bubble interior and entered the cluster
of local interstellar clouds flowing past the Sun, within the past 140,000
years, and again when the Sun entered the local interstellar cloud now
surrounding and inside of the solar system, sometime during the past 44,000
years.

\\ ( http://arXiv.org/abs/astro-ph/0601359 , 848kb)

------------------------------------------------------------------------------

Paper: astro-ph/0601357
Date: Tue, 17 Jan 2006 02:45:13 GMT (306kb)

Title: Pulsar rotation measures and the large-scale structure of Galactic
magnetic field

Authors: J.L. Han (NAOC), R.N. Manchester (ATNF), A.G. Lyne (Jodrell Obs), G.J.
Qiao (PKU), W. van Straten (UTB)

Comments: ApJ accepted. 16 pages, 14 figures, 2 tables, 223 pulsar RMs
\\
The large-scale magnetic field of our Galaxy can be probed in three
dimensions using Faraday rotation of pulsar signals. We report on the
determination of 223 rotation measures from polarization observations of
relatively distant southern pulsars made using the Parkes radio telescope.
Combined with previously published observations these data give clear evidence
for large-scale counterclockwise fields (viewed from the north Galactic pole)
in the spiral arms interior to the Sun and weaker evidence for a
counterclockwise field in the Perseus arm. However, in interarm regions,
including the Solar neighbourhood, we present evidence that suggests that
large-scale fields are clockwise. We propose that the large-scale Galactic
magnetic field has a bisymmetric structure with reversals on the boundaries of
the spiral arms. Streaming motions associated with spiral density waves can
directly generate such a structure from an initial inwardly directed radial
field. Large-scale fields increase toward the Galactic Center, with a mean
value of about 2~$\mu$G in the Solar neighbourhood and 4~$\mu$G at a
Galactocentric radius of 3 kpc.

\\ ( http://arXiv.org/abs/astro-ph/0601357 , 306kb)

Posted by: AlexBlackwell Jan 18 2006, 09:23 PM

Forgive me for asking, but what do any of these three preprints, interesting though they might be, have to do with the topic of the thread (viz., "Seti And Particularly Seti@home...")?

Posted by: ljk4-1 Jan 18 2006, 10:17 PM

They are an examination of how the galactic environment interacts with Earth and Sol. This will give us some idea of what conditions may be like elsewhere and how life might be affected by such interactions. This adds parameters to the possibility of life elsewhere, including the kind that might be found by SETI.

Perhaps I should have put this in your recent Astrobiology thread (thank you for the alert, BTW).

Posted by: AlexBlackwell Jan 18 2006, 10:27 PM

That's stretching it, I think The structure of the board, however, often makes it hard to place notices of papers in topical threads.

Having said that, I'm not complaining. I do appreciate the heads-up on the arXiv preprints. I used to run daily searches on the LANL server and post interesting papers in my Yahoo! planetary_sciences group. So, when someone else (you, for instance) does the hard work, far be it from me to look a gift horse in the mouth.

Posted by: Myran Jan 18 2006, 10:39 PM

Posted by: ljk4-1 Jan 19 2006, 03:06 AM

That's stretching it, I think    The structure of the board, however, often makes it hard to place notices of papers in topical threads.

Having said that, I'm not complaining.  I do appreciate the heads-up on the arXiv preprints.  I used to run daily searches on the LANL server and post interesting papers in my Yahoo! planetary_sciences group.  So, when someone else (you, for instance) does the hard work, far be it from me to look a gift horse in the mouth.

Posted by: ljk4-1 Jan 19 2006, 03:10 AM

I agree we're somewhat off topic here, yet the question if one alien species would consider it worth the effort of undertaking interstellar journeys can have a consequence for SETI. Civilisations that colonize new worlds will be easier to find compared to if they only are found on a single planet.

Posted by: dvandorn Jan 19 2006, 06:02 AM

It's been asked, why would you want to try and develop a civilization capable of moving from one star system to another -- or perhaps, from one galaxy to another? These would be Kardyshev Type 3 civilizations, if I recall correctly.

One reason I can think of is that the Milky Way may well be doomed. Anyone living in about 60% to 70% of the galaxy can plainly see that M31 is heading straight for us, and that our two galaxies will collide in about 3 or 4 billion years.

We don't yet know if such a collision will have a really deleterious effect on the habitability of currently habitable planets in this galaxy. But perhaps the odds are good that most of us will be wiped out when the galaxies collide.

And that any sufficiently advanced ETI has deduced this. And has moved completely out of the doomed Milky Way -- perhaps to stars within the Magellanic Clouds, perhaps to a more distant galaxy not in quite so iminent danger of collision.

I know, it's a pretty far-out reason for the lack of advanced ETI in the Milky Way -- but it *is* a viable one.

-the other Doug

Posted by: ljk4-1 Jan 19 2006, 02:17 PM

It's been asked, why would you want to try and develop a civilization capable of moving from one star system to another -- or perhaps, from one galaxy to another?  These would be Kardyshev Type 3 civilizations, if I recall correctly.

One reason I can think of is that the Milky Way may well be doomed.  Anyone living in about 60% to 70% of the galaxy can plainly see that M31 is heading straight for us, and that our two galaxies will collide in about 3 or 4 billion years.

We don't yet know if such a collision will have a really deleterious effect on the habitability of currently habitable planets in this galaxy.  But perhaps the odds are good that most of us will be wiped out when the galaxies collide.

And that any sufficiently advanced ETI has deduced this.  And has moved completely out of the doomed Milky Way -- perhaps to stars within the Magellanic Clouds, perhaps to a more distant galaxy not in quite so iminent danger of collision.

I know, it's a pretty far-out reason for the lack of advanced ETI in the Milky Way -- but it *is* a viable one.

-the other Doug

Posted by: ljk4-1 Jan 24 2006, 04:07 PM

RELEASE: 06-03AR

NASA AMES CENTER DIRECTOR JOINS SETI INSTITUTE

G. Scott Hubbard, director of NASA Ames Research Center, located in California's Silicon Valley, today announced that he has accepted a new position as the Carl Sagan Chair for the Study of Life in the Universe at the SETI Institute in Mountain View, Calif., effective Feb. 15, 2006.

As holder of the Carl Sagan Chair, Hubbard will work to strengthen the SETI Institute's capability, visibility and support for its research into the origin of life, and how it might be found on other worlds, in the planets and moons of our solar system or beyond.

"The people at Ames are among the best in the agency, and it has been both a pleasure and an honor to serve as the Ames center director. I know Ames will continue to play a creative and critically important role in NASA's programs," Hubbard said. "My new position at the SETI Institute allows me to return to the research arena and pursue a lifelong interest in the search for life in the universe and its origins on Earth. I believe this field, which is often called astrobiology, is both the scientific heart of the exploration vision and the most exciting area of research today. We have a chance to learn things that, only a generation ago, would have seemed beyond our capabilities," he added.

"Scott is the perfect candidate for the Carl Sagan Chair," remarked Thomas Pierson, chief executive officer of the SETI Institute. "He has a solid background in the relevant sciences and has proven himself to be an effective and widely admired leader. As the holder of the Carl Sagan Chair, Scott will be engaged with many audiences, furthering their understanding about science and its potential for new discoveries. Scott will bring both expertise and enthusiasm to this task and will be a terrific representative for the Institute both domestically and internationally," Pierson added.

Hubbard began his career at NASA Ames in 1987, and has served as the center director since 2002, accumulating numerous awards and honors along the way. He is known for his innovative approach to collaborations between government, academia and the private sector, particularly as embodied by the development of the award-winning NASA Research Park, research collaborations with Google Inc., and the creation of the Project Columbia supercomputer, one of the world's fastest.

His many accomplishments include his work on the Columbia Accident Investigation Board, which helped to establish the physical cause of the loss of the space shuttle Columbia. His tenure as the first NASA Mars program director redefined NASA's robotic Mars missions and led to the successful and ongoing reconnaissance of Mars by the Mars Exploration Rovers. He served as the manager for the Lunar Prospector mission that found water ice at both of the moon's poles, and he is credited with conceiving the Mars Pathfinder mission. As center director, he managed NASA Ames through a critical transition to better align the center's capabilities with the Vision for Space Exploration, resulting in the award of the management of the Robotic Lunar Exploration Program. Hubbard also served as the first director of NASA's Astrobiology Institute.

NASA Ames Research Center specializes in research geared toward creating new knowledge and new technologies that span the spectrum of the agency's missions and interests, with a focus on the Vision for Space Exploration.

The SETI Institute is a non-profit research organization addressing the broad question of life in the universe. It is home to many dozens of scientists engaged in investigating the origin, nature and distribution of life. Its board of trustees includes many eminent scientists, including two winners of the Nobel Prize, as well as numerous academics and technology innovators.

Additional information about NASA Ames and the SETI Institute is available on the Internet at:

http://www.nasa.gov/centers/ames/home/index.html

http://www.seti.org

Posted by: ljk4-1 Jan 28 2006, 03:39 AM

The Ultimate SETI Signal

Robert Carrigan (Fermi National Accelerator Laboratory) drew quite a bit of attention last summer when he suggested that SETI signals could contain harmful information, perhaps created by a so-called ‘SETI hacker.’ Carrigan’s article has now appeared in Acta Astronautica, and it’s stuffed with beguiling ideas even if you find the premise unlikely.

“…will a SETI signal be altruistic, benign or malevolent?” Carrigan asks. “It would help to understand the motivations of a message before reading too much of it. Like Odysseus, we may have to stuff wax in the ears of our programmers and strap the chief astronomer to the receiving tower before she is allowed to listen to the song of the siren star.”

...

“The most important point is that large amounts of information can be transferred inexpensively at the speed of light even with current technologies. In addition, the message size can easily be so large that the underlying intent of the message would not be apparent.”

The paper, which belongs on the shelves of disks of anyone following the SETI search, is “Do potential SETI signals need to be decontaminated?” in Acta Astronautica 58 (2006), pp. 112-117.

Carrigan’s own site contains earlier work on the theory:

http://home.fnal.gov/~carrigan/SETI/SETI_Hacker.htm

The full Centauri Dreams article is here:

http://www.centauri-dreams.org/?p=522

Posted by: Richard Trigaux Jan 28 2006, 01:21 PM

The Ultimate SETI Signal

Robert Carrigan (Fermi National Accelerator Laboratory) drew quite a bit of attention last summer when he suggested that SETI signals could contain harmful information, perhaps created by a so-called ‘SETI hacker.’ Carrigan’s article has now appeared in Acta Astronautica, and it’s stuffed with beguiling ideas even if you find the premise unlikely.

“…will a SETI signal be altruistic, benign or malevolent?” Carrigan asks. “It would help to understand the motivations of a message before reading too much of it. Like Odysseus, we may have to stuff wax in the ears of our programmers and strap the chief astronomer to the receiving tower before she is allowed to listen to the song of the siren star.”

...

“The most important point is that large amounts of information can be transferred inexpensively at the speed of light even with current technologies. In addition, the message size can easily be so large that the underlying intent of the message would not be apparent.”

The paper, which belongs on the shelves of disks of anyone following the SETI search, is “Do potential SETI signals need to be decontaminated?” in Acta Astronautica 58 (2006), pp. 112-117.

Carrigan’s own site contains earlier work on the theory:

http://home.fnal.gov/~carrigan/SETI/SETI_Hacker.htm

The full Centauri Dreams article is here:

http://www.centauri-dreams.org/?p=522

Posted by: ljk4-1 Feb 6 2006, 03:53 PM

Send a message to 47 Ursae Majoris:

http://www.cosmicconnexion.com/static/index.html

Apparently this exercise in Active SETI (ASETI) is the "celebration"
part of the COROT astronomy satellite mission to find extrasolar
planets, including Earth-size (Telluric) ones. COROT is set for
launch in June of 2006.

http://smsc.cnes.fr/COROT/

http://www.esa.int/science/corot

http://cfa-www.harvard.edu/planets/corot.html


Not that we should refine our ETI searches just to planets
(some would argue we will have better chances aiming our
telescopes at regions which show up in the infrared but not
the optical), but 47 UM does have at least two Jupiter-class
worlds orbiting at fairly large distances from their star (unlike
all those other exogiants that practically skim the photospheres),
allowing at least the possibility of an Earth-size world in the
habitable zones.

See here:

http://www.solstation.com/stars2/47uma.htm

Will the messages being sent out by CNES "survive" the 46 light year
journey to 47 UM? Will they even be comprehensible to anyone
there? Will it at least let any ETI present know they are not alone
and motivate them to respond? Is it wiser to keep our mouths
shut and let someone else contact us first? Or do we gain nothing
by hiding under our beds - except dust?

Posted by: ljk4-1 Feb 6 2006, 08:16 PM

MONDAY, FEBRUARY 6, 2006 on the National Geographic Channel

Naked Science: "Alien Contact" at 9P et/pt

Are we the only intelligent species in the universe? Find out why
some scientists are convinced we're on the verge of finding other
life forms as we separate scientific fact from science fiction in
the search for extraterrestrials.

Visit the National Geographic Channel home page.

http://ng.chtah.com/a/tBD55y6ASJ4TXAcfOn6AOOv6R.ASJ-ROYQ/ngs6

Posted by: ljk4-1 Feb 7 2006, 04:22 PM

Science/Astronomy:

* The Growing Habitable Zone: Locations for Life Abound

http://www.space.com/scienceastronomy/060207_habitable_zone.html

New discoveries made over the past few decades have forced scientists to expand
their definition of a circumstellar habitable zone, the region around a star
where liquid water and life can exist.

Posted by: ljk4-1 Feb 9 2006, 06:49 PM

Astrophysics, abstract
astro-ph/0602092

From: Mikhail V. Medvedev [view email]

Date: Sat, 4 Feb 2006 08:41:11 GMT (144kb)

Do extragalactic cosmic rays induce cycles in fossil diversity?

Authors: Mikhail V. Medvedev, Adrian L. Melott (University of Kansas)

Comments: 13 pages, 3 figures, submitted to Nature

Subj-class: Astrophysics; Geophysics; Plasma Physics; Atmospheric and Oceanic Physics; Populations and Evolution

The idea of cycles in fossil diversity has recently been put on a firm statistical footing, revealing a 62{plus-minnus}3-million-year cycle in the number of marine genera. The strong signal requires a periodic process extending back at least 540 My, which is difficult to explain by any terrestrial process. While astro- and geophysical phenomena may be periodic for such a long time, no plausible mechanism has been found. The fact that the period of the diversity cycle is close to the 64 My period of the vertical oscillation of the Solar system relative to the galactic disk is suggestive. However, any model involving cosmogenic processes modulated by the Sun's midplane crossing or its maximal vertical distance from the galactic plane predicts a half-period cycle, i.e. about 32 My. Here we propose that the diversity cycle is caused by the anisotropy of cosmic ray (CR) production in the galactic halo/wind/termination shock and the shielding effect of the galactic magnetic fields. CRs influence cloud formation, can affect climate and harm live organisms directly via increase of radiation dose. The CR anisotropy is caused by the galactic north-south asymmetry of the termination shock due to the interaction with the ``warm-hot intergalactic medium'' as our galaxy falls toward the Virgo cluster (nearly in the direction of the galactic north pole) with a velocity of order 200 km/s. Here we revisit the mechanism of CR propagation in the galactic magnetic fields and show that the shielding effect is strongly position-dependent. It varies by a factor of a hundred and reaches a minimum at the maximum northward displacement of the Sun.

Very good phase agreement between maximum excursions of the Sun toward galactic north and minima of the fossil diversity cycle further supports our model.

http://arxiv.org/abs/astro-ph/0602092

Posted by: Marz Feb 10 2006, 05:17 PM

Astrophysics, abstract
astro-ph/0602092

From: Mikhail V. Medvedev [view email]

Date: Sat, 4 Feb 2006 08:41:11 GMT  (144kb)

Do extragalactic cosmic rays induce cycles in fossil diversity?

Authors: Mikhail V. Medvedev, Adrian L. Melott (University of Kansas)

Comments: 13 pages, 3 figures, submitted to Nature

Subj-class: Astrophysics; Geophysics; Plasma Physics; Atmospheric and Oceanic Physics; Populations and Evolution

The idea of cycles in fossil diversity has recently been put on a firm statistical footing, revealing a 62{plus-minnus}3-million-year cycle in the number of marine genera. The strong signal requires a periodic process extending back at least 540 My, which is difficult to explain by any terrestrial process. While astro- and geophysical phenomena may be periodic for such a long time, no plausible mechanism has been found. The fact that the period of the diversity cycle is close to the 64 My period of the vertical oscillation of the Solar system relative to the galactic disk is suggestive. However, any model involving cosmogenic processes modulated by the Sun's midplane crossing or its maximal vertical distance from the galactic plane predicts a half-period cycle, i.e. about 32 My. Here we propose that the diversity cycle is caused by the anisotropy of cosmic ray (CR) production in the galactic halo/wind/termination shock and the shielding effect of the galactic magnetic fields. CRs influence cloud formation, can affect climate and harm live organisms directly via increase of radiation dose. The CR anisotropy is caused by the galactic north-south asymmetry of the termination shock due to the interaction with the ``warm-hot intergalactic medium'' as our galaxy falls toward the Virgo cluster (nearly in the direction of the galactic north pole) with a velocity of order 200 km/s. Here we revisit the mechanism of CR propagation in the galactic magnetic fields and show that the shielding effect is strongly position-dependent. It varies by a factor of a hundred and reaches a minimum at the maximum northward displacement of the Sun.

Very good phase agreement between maximum excursions of the Sun toward galactic north and minima of the fossil diversity cycle further supports our model.

http://arxiv.org/abs/astro-ph/0602092

Posted by: PhilCo126 Feb 10 2006, 06:14 PM

Although pre-SETI period, this might be the right topic to talk about the WOW signal:
http://www.bigear.org/wow.htm

Posted by: ljk4-1 Feb 10 2006, 06:45 PM

Although pre-SETI period, this might be the right topic to talk about the WOW signal:
http://www.bigear.org/wow.htm

Posted by: Myran Feb 10 2006, 06:57 PM

Ahh yes the 'Wow!' signal, though I do think it was detected during a SETI search, so it wasnt 'pre' in any way.
I tend to remember they did quite some work trying to rule the possibility it was a signal from Earth or any spacecraft, and so its a good detection.
But since it havnt repeated or been spotted again it cant have been a communication attempt. A wild speculation would be a space radar where we happened to be in the line of sight when somebody or something did one search or study of asteroids or other small worlds. More likely, some kind of odd Maser that happened to burp all its energy on a single frequency. Regardless, 'Wow' is one of the few that makes it worth to continue listening.

Posted by: ljk4-1 Feb 16 2006, 06:36 PM

Science/Astronomy:

* Sharing the Allen Telescope Array

http://www.space.com/searchforlife/seti_ata_backus_060216.html

The Allen Telescope Array (ATA) is the first of a new generation of radio
telescopes. It is a radical departure from traditional radio telescope design
and construction.

Posted by: ljk4-1 Feb 21 2006, 10:33 PM

A US astronomer has drawn up a shortlist of the stars most likely to harbour intelligent life.

Scientists have been listening out for radio signals from other solar systems in the hope of detecting civilisations other than our own.

Margaret Turnbull at the Carnegie Institution in Washington DC looked at criteria such as the star's age and the amount of iron in its atmosphere.

Her top candidate was beta CVn, a Sun-like star 26 light-years away.

Dr Turnbull had previously identified about 17,000 stellar systems that she thought could be inhabited.

From these, she has selected five stars that look most likely to support intelligent extraterrestrial life forms - if they exist.

"I've chosen five to advertise the very best places to move to if we had to, or to point the telescope at," she told the BBC.

http://news.bbc.co.uk/2/hi/science/nature/4728228.stm

Posted by: ljk4-1 Feb 22 2006, 10:22 PM

The first-ever Optical SETI Dedicated Observatory, funded by The Planetary Society, is due to open in April, 2006!

High on a wooded ridge in Harvard, Massachusetts an odd-looking structure has sprung up recently. Appearing from a distance like a small work shed, a closer inspection reveals some unusual features, including a retractable roof and a large side window with a sliding screen. A look inside is even more puzzling, for there, bolted to the ground, one finds a large elongated object, made of metal bars and mirrors. This strange object, that looks like nothing at all, represents one of the most ambitious SETI projects ever undertaken: an optical telescope dedicated exclusively to the search for extraterrestrial life. In April of 2006 it will point its giant mirror at the sky, and begin a systematic search for light signals from an alien civilization.

The new observatory is one of the largest SETI projects ever sponsored by The Planetary Society. Since its founding, the Society has been a leading advocate of the Search for Extraterrestrial Intelligence, supporting a wide variety of searches, making use of different approaches. Most of these - and the largest ones - were radio SETI projects such as BETA, SERENDIP, and, of course, SETI@home. Now, after decades of listening, The Planetary Society has turned its eyes to the skies to scan for possible light signals. "We have been listening for alien signals for decades,"said Louis Friedman, Executive Director of the Planetary Society; "it's time we started to watch for signals as well."

http://planetary.org/programs/projects/seti_optical_searches/

Posted by: ljk4-1 Feb 24 2006, 04:25 PM

http://www.msnbc.msn.com/id/11485023/#060222a

Feb. 22, 2006 | 10 p.m. ET

Take me to your funder: His Seahawks may not have won the Super Bowl, and he may not have gotten that congratulatory phone call from the White House, but software billionaire Paul Allen has what may be an even bigger speed-dial distinction: If the SETI Institute ever detects radio signals from an alien civilization, Allen is No. 1 on the list of VIPs to call, says institute astronomer Jill Tarter.

Tarter, who heads the California-based institute's Center for SETI Research, has been involved in radio searches for extraterrestrial intelligence for more than two decades — including a stretch in the 1980s and 1990s when the search received funding from NASA.

Back then, NASA had set up a detailed procedure for letting politicos know about the detection of potential alien signals before word was officially released to the public. But after government funding for SETI research was cut off in 1994, the SETI Institute has been relying exclusively on private support for its alien-hunting activities (although it still receives NASA grants for non-SETI research and education).

When SETI's funding sources changed, so did the alien alert system, Tarter told reporters in St. Louis at last week's annual meeting of the American Association for the Advancement of Science.

"Today it is in fact a group of very generous philanthropists who will get the call before we get a press conference," Tarter said.

Later, Tarter told me that Allen was first on that phone list. That's doubtless because of his very, very generous support for the institute — which has amounted to $25 million so far.

The crown jewel for that support is the Allen Telescope Array, a network of linked radio telescopes that is being built in Northern California under the auspices of the institute as well as the University of California at Berkeley. The array is due to start operations with 42 dishes online this spring, representing one more big step toward the 350-dish goal.

Former Microsoft executive Nathan Myhrvold, a million-dollar backer of the telescope array, is also on the list, Tarter said.

At the AAAS meeting, astronomers announced five top prospects for the SETI search — and Tarter said those stars would certainly be targeted for closer looks by the telescope array, a task that takes about a day per star system.

However, such targeted inspections are not the first order of business once operations begin. Instead, the institute is planning a large-area survey of our Milky Way galaxy's central region, which will allow for other radio astronomy observations not related to the search for alien signals. That's an important element of the Allen Telescope Array: that it's not just for SETI any more.

So even if there's no message from E.T., the contributions from Allen, Myhrvold and those other "very generous philanthropists" will have an impact on astronomy for decades to come. And you never know: Someday that call to Paul Allen just might come through.

"I'm sure it's a call we'd all be looking forward to," said Michael Nank, a spokesman for Allen's Vulcan Inc.

Posted by: ljk4-1 Apr 4 2006, 03:46 PM

Planetary Radio

A Bright New Star in the Search for Extraterrestrial Intelligence

Airdate: Monday, April 3, 2006
Running Time: 00:28:52
Listen: Windows Media | MP3

Harvard professor and SETI pioneer Paul Horowitz is about to unveil a powerful new tool dedicated to finding a brilliant flash of laser light coming from a distant civilization. He and his graduate student Andrew Howard talk with Mat about the new telescope, the first-ever Optical SETI Dedicated Observatory.

Emily Lakdawalla is the go-to person if you're wondering why the Mars Exploration Rovers take a day off now and then. Bruce Betts knows What's Up, and presents a new space trivia contest.

Guests - Paul Horowitz, Harvard University physicist

Andrew Howard

http://www.planetary.org/radio/show/00000171/

Posted by: Bill Thompson Apr 7 2006, 11:08 PM

QUOTE (deglr6328 @ Nov 20 2005, 06:49 AM)

QUOTE (ljk4-1 @ Feb 7 2006, 04:22 PM)

Posted by: Bob Shaw Apr 7 2006, 11:34 PM

Bill:

I suspect that mere life is all over the place, but intelligence is woefully rare; if our kind of folk were even about for a brief time elsewhere then the universe would be teeming with AI spaceprobes, of which there are - sadly - no signs.

If humanity has any form of manifest destiny, then I say it's simple: get out there and infect the universe with intelligence!

In the meantime, let's support the exploration of our backyard!

Bob Shaw

Posted by: ljk4-1 Apr 7 2006, 11:35 PM

QUOTE (Bill Thompson @ Apr 7 2006, 07:08 PM)

Posted by: Richard Trigaux Apr 8 2006, 02:00 PM

Curious remark, ljk4-1, that the pessimistic point of view (no life in the universe) has its origin into this arbitrarian catholic dogma. And that it was taken as it, without any questioning, by many "rationnal" scientists...


There was already a link to the SETI results here in this thread. This chart indicated that:

-SETI would be unable to find a twin planet of our earth at more than one light-year. So there is still many place for Earth-like civilizations.
-There are no type II civilizations nearby, indicating that they may be not very common.
-There is no type III civilization in our galaxy.
Also tens of canditate signals were found (statistically very unlikely to arise from noise), but did not passed other criteria such as repeating in the same place.


So there is no reason yet to shout that SETI failed and that we are alone. Such a statement is just an exageration, a distortion of the results. If our direct neighbourhood was swarming with spaceships using cell phones, SETI could not detect them. Or just some lonely candidate signals from times to times.


Peer reweved SETI papers? Good idea. But who would be the peers, if there are still so strong and useless prejudices against the SETI search???


Why our skies would not be swarming with ET probes, as predicted by the latest values for the parametres in the Drake equation? SETI cannot answer to this question. We can just do some speculations:
-we did not estimated corectly a parameter in the Drake equation
-ET civs would exist, but there is no way to send interstellar probes
-Due to gamma ray bursts, life was difficult in ancient times in our galaxy, and we would be among the very firsts to survive and evolve to civilization.
-civilizations evolve in other way than just linearly increase their technology level. (I explore this hypothesis in my novels "the missing planets" and "Dumria").


This argumentation has a look of having being already done in this thread. I would like that this SETI thread would be used to comment SETI, not just for ranting against ET peoples, or for pessimistic statements arizing from restrictive conceptions of life. If it is just for that, it would be better that Doug just locks this thread, according to his new forum scope. (Please Doug if you do, still allow to place links to suitable SETI forums).

Posted by: Richard Trigaux Apr 8 2006, 08:47 PM

Reading back the article on the "wow signal", I found that the one-time large candidate signals could be reflections of Earth radio sources onto space debris or satellites. Such signals would be very strong, narrow frequency, they would match the antenna pattern like with the wow signal, and seem to come from space. But they are not from ET origin. This is likely why one-timers are all rejected by the SETI protocols.


From where the idea, to avoid such false detections, to send the SETI antenna in space. Easy to say, but large radioastronomy dishes are tens of metres large, see hundred metres, and very heavy. A simple solution would be to send an array of dipoles mounted on something ressembling a spider web, rotating to keep its shape. Phase shifts on every dipole would allow to change the direction of reception. Such an apparatus would weight only some tons and could be folded into a common rocket upper stage.

But if this is useful for SETI, it can be usefull too for any other use of radioastronomy dishes, observation or deep space network as well. And it would be free of any Earth interference, a growing problem today. And the cost? we anyway save the cost of a large dish.

Posted by: dilo Apr 8 2006, 09:05 PM

Nice idea, Richard... but I have a couple of observations on it.
First, I fear that widely spaced, small dipoles would have a small effective area, so resulting antenna would have small gain/sensitivity (but potentially very good beam width / resolution).
Second, I think that you should go very far from Earth (far lunar side?) in order to drastically reduce artificial interferences...
Anyway, I recall of some projects on inflatable antenna dishes which should solve the problem.

Posted by: Richard Trigaux Apr 9 2006, 07:57 AM

QUOTE (dilo @ Apr 8 2006, 09:05 PM)

Posted by: Bob Shaw Apr 9 2006, 11:37 AM

Back in the 1960s there were several balloon satellites other than the Echo series - one USAF test used a 10.5m structure built by Goodyear which was inflated in orbit, but then the plastic balloon material disintegrated under the influence of solar UV to form a rigid but very thin open aluminium structure, a so-called grid-sphere balloon. The vehicle was launched on July 13, 1966 from Vandenberg aboard an Atlas booster. Orbit altitude was 620 miles and tests revelaed that it was able to reflect radio waves five times more efficiently than a traditional balloon.

This sort of technology might well be applicable to large orbital antenna farms.

Bob Shaw

Posted by: Bill Thompson Apr 9 2006, 02:25 PM

QUOTE (ljk4-1 @ Apr 7 2006, 11:35 PM)

QUOTE (ljk4-1 @ Apr 7 2006, 11:35 PM)

Posted by: ljk4-1 Apr 9 2006, 03:13 PM

QUOTE (Bill Thompson @ Apr 9 2006, 10:25 AM)

Posted by: Richard Trigaux Apr 9 2006, 03:15 PM

QUOTE (Bill Thompson @ Apr 9 2006, 02:25 PM)

QUOTE (Bill Thompson @ Apr 9 2006, 02:25 PM)

Posted by: Bill Thompson Apr 10 2006, 05:29 AM

QUOTE (ljk4-1 @ Apr 9 2006, 03:13 PM)

Posted by: Richard Trigaux Apr 10 2006, 06:36 AM

QUOTE (Bill Thompson @ Apr 9 2006, 02:25 PM)

Posted by: Bill Thompson Apr 10 2006, 11:53 PM

The wrath of Xenu is an explaination why we seem to be alone. I am joking, of course.

But seriously, one possible explanation might be that the gaps in the steps of microbial evolution where we do not understand how something self replicating evolved from non replicating polymers is that it was enormously great luck and planet Earth is the recipient of winning (for lack of a better term) a cosmic lottery. Maybe life is a game of chance and the odds of winning are 400 billion to one.

Or has this been proven to be wrong?

Posted by: Richard Trigaux Apr 11 2006, 07:54 AM

QUOTE (Bill Thompson @ Apr 10 2006, 11:53 PM)

Posted by: Bill Thompson Apr 11 2006, 11:18 PM

QUOTE (Richard Trigaux @ Apr 11 2006, 07:54 AM)

Posted by: Bob Shaw Apr 12 2006, 12:28 AM

QUOTE (Richard Trigaux @ Apr 11 2006, 08:54 AM)

Posted by: Richard Trigaux Apr 12 2006, 06:44 AM

Bill and Bob, be reassured, I don't want too to start one of these interminable discution, and I shall not further reply to any argument in the kind "we don't know how it happened so it did not happened elsewhere" or "we are the unique example known so we must be unique" or "we are special so we are unique". Such arguments are simply of no help and out of place in a science forum.

Yes we can say "must" in statistics, when great numbers are involved. The decay of radioactive elements is an example: a completelly random process, even not time-dependent, and however it is the best clock we have for past events. And for instance Al26 "must" have disappeared from Enceladus. So you understand that rare events "must" happen with enouh time.

So "my" vision of appearance of life and its evolution as a series of random steps, which can go all the way from prebiotic molecules to intelligence and further (yes the further step is alrready engaged on Earth, and it may explain why we don't find other technological civs), this vision is not just a dogmatic vision, it is based on statistics, and on well documented real world models such as the "evolution" of tumors by random mutations. each tumor type depends on a series of mutations, and, if we compare each tumor to a planet, it is remarkable that all the tumors of the same type evolve in the same way, even in dependance of completelly random events, and in total independance of each other. There is even a diret relation between the size reached by the tumor and the happening of each mutation.

I agree with you Bob that, even if microbes are very common, the appearance of intelligence must be much more rare, as it depends of the availability of more specific conditions, and of enough time (four billion years on Earth) without deadly perturbations. So we cannot expect to find intelligence in the Europa ocean, even if there are plenty of microbes since four billions years. Similarly we cannot expect to find intelligence on large stars, as their life span is too short. And one of the main constrain known today, to add to the Drake equation, is the account of deadly events such as large meteorite impacts, gamma ray bursts, close supernovas, etc. This makes of star clusters bad SETI candidates and Virgo elliptic galaxies best canditates (better than ours). This problem is the simplest solution to the Fermi paradox, but it needs to be proven before being brandished as "the truth".

I would like to continue this discution, but so long as there are no definitive statements as above.

Posted by: ljk4-1 Apr 12 2006, 02:28 PM

The Planetary Society's Optical SETI Telescope at Oak Ridge Observatory
in Harvard, Massachusetts, has begun its search. Three news items here:


Planetary Society Opens World's First Dedicated Optical SETI Telescope

New Search for Extraterrestrial Intelligence Begins

Pasadena, CA, —Today, April 11, 2006, The Planetary Society dedicated a new optical telescope at an observatory in Harvard, Massachusetts -- one designed solely to search for light signals from alien civilizations. Read more.

Opening ceremonies for The Planetary Society's Optical SETI Telescope featured Project Director Paul Horowitz of Harvard University; Planetary Society Chairman Neil deGrasse Tyson, director of New York's Hayden Planetarium; and Society Executive Director Louis Friedman.

"With the launch of The Planetary Society's Optical SETI Telescope," said Friedman, "we are proud to be part of a new voyage of discovery with this great Harvard team."

The new telescope is the first dedicated optical SETI telescope in the world. Its 72-inch primary mirror is larger than that of any optical telescope in the U.S. east of the Mississippi River.

Under the direction of Horowitz and his team, the optical SETI telescope will conduct a year round, all-sky survey, scanning the entire swath of our Milky Way galaxy visible in the northern hemisphere.

Full article here:

http://planetary.org/about/press/releases/2006/0411_Planetary_Society_Opens_Worlds_First.html


Looking for alien lasers, not radios

NewScientist.com news service April 11, 2006

*************************

The first optical telescope
dedicated to the hunt for alien
signals, the Planetary Society's
Optical SETI (OSETI) telescope at
Harvard's Oak Ridge Observatory, has
opened. Once running, OSETI's
processors will carry out a trillion
measurements per second, in a
year-round survey of the sky. It
will be able to pick out flashes of
light that are...

http://www.kurzweilai.net/email/newsRedirect.html?newsID=5458&m=7610


Harvard's new telescope to boost search for alien life

Will scan heavens for flashes of light

By Douglas Belkin, Globe Staff | April 12, 2006

To quote:

Horowitz compared the previous generation of the Optical Search for Extra-Terrestrial Intelligence, or OSETI, to searching the skies through a soda straw -- viewing only a very narrow spot of the heavens at once. This telescope, built for about $400,000, scans a broad line in the sky.

As the Earth moves, the stars pass through that line. In about 200 nights the scope can observe the entire sky visible from the northern hemisphere.

The pace of observation: 100,000 times faster than any previous scope.

To analyze the massive amount of data being sucked in through the scope's 72-inch mirror, a team of graduate and undergraduate students built a computer able to wade through 1 trillion bits of information per second -- about as much information as is contained in every book in the Library of Congress.

''The technology is absolutely on the cutting edge," said Louis Friedman, executive director of the Planetary Society, a nonprofit group of scientists and space enthusiasts that funded the telescope. ''It feels like the Wright brothers working out of their bike shop; they're using chips never seen before."

Friedman compared building the scope to launching a space ship. The stakes, he said, could not be higher.

Full article here:

http://www.boston.com/news/education/higher/articles/2006/04/12/harvards_new_telescope_to_boost_search_for_alien_life/

Posted by: Toymaker Apr 14 2006, 01:47 PM

Seti always worked on its own assumptions, and perhaps it is ironic that the only civilization that we now(ours) isn't going alongside these assumptions. We aren't sending dozens of high energy signals to other stars, as SETI is hoping other's do. Of course if I am wrong, please correct me. Our own normal transmissions aren't detectable very far, and any other civilisation on equal scale wouldn't be detactable also.
Interesting link:
http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html

Posted by: Marz Apr 14 2006, 03:30 PM

QUOTE (Toymaker @ Apr 14 2006, 08:47 AM)

Posted by: Richard Trigaux Apr 14 2006, 08:23 PM

Interesting remarks, Marz and Toymaker. Some replies in random order:

-The idea as what intelligence MUST be unique is not a scientific idea, it rather arises from an old catholic dogma. Today we simply don't know and are still far of knowing.

-The ideas as what other civs MUST be bad, uncaring for us or ununderstandable for us also seem to arise from pessimistic philosophies, not from a reasonable speculation about what is possible. And really many things are possible...

-The SETI started with a simple view: a radio telescope like the one at Arecibo could dialogue with its peer at hundreds of light years. At this time, Earth was teeming with powerfull radars and radio stations, some sending megawatts. Unforeseen were the more recent evolutions: internet and cable replacing air broadcast, stealth military radars... So in a way you are true.

-Today SETI did not detected a Kardanchev type III civilization. But it would not detect earth at more than one light year, so it is clear that we cannot yet assert that there are no radio technology in the skies, and still by many orders of magnitude. It is a bit like if the seach on gravity waves was abandonned in the 1970' because the first detectors at this time found nothing. We learned since that these detectors lacked more than ten orders of magnitude in sensitivity. SETI is still in the state of gravitationnal search in the 1970'...

-If SETI really finds nothing, so it will be anyway a tell tale experiment, like the Michelson Morley experiment. The Michelson Morley told us that there was something completely wrong in our understanding of physics. It was a very productive experiment. Similarly te SETI already told us that there is not such a nighmare as a Kardanchev type III civ, or a Starwars world.

-Toymaker I liked your analysis on the Kardanchev classification. Nothing tells us that we must evolve that way. It is even more and more apparent that ecological or social disorders would forbid us the way of mega-technology.




The Fermi paradox could have many solutions. the most common is that we would be in a kind of "zoo". I don't like this one too much, but I can tell some other explanations which are much less common, but being still scientifically valid:
-There is simply no mean to travel into interstellar space, no quantum communication, etc... (or there are such things, but they need first to establish a base on Earth).
-ETs are roaming all the space routes, but no civ, whatever they are highly compassionned sages or evil scruppleless conquerors, will never attempt a landing on a planet already infected with its own life, simply because they would be sick from this.
-Civs find other ways to evolve and achieve happiness than with technology.
-UFOs are often invoked as evidences of ETs visits, even by some SETI specialists. But this phenomenon is much more ancient than SF movies, and it happens that in ancient times it showed rather mythological scenes than SF scenes. For this reason and many others, I strongly suspect that UFOs are not ET spaceships.

Posted by: Bob Shaw Apr 14 2006, 08:31 PM

QUOTE (Richard Trigaux @ Apr 14 2006, 09:23 PM)

Posted by: Richard Trigaux Apr 14 2006, 09:15 PM

Use a parental control if you don't like it. .

Posted by: Toymaker Apr 14 2006, 09:41 PM

I also would like to ask if anybody knows the an answer to the following issue(please do mind that I am no scientist ). If SETI worked on assumption that they are searching for Kardashev type civilisations engaging in high megascale construction and energy utilisation have they ever considered searching for signs of such civilisations other then radio ? Of course this is highly SF to the average person, but If they were assuming radio transmissions on such scale, why not search for Dyson Spheres, infrared signs of civilisations around other stars using high energies, megascale constructions etc ? After all It would fall into the same activity expected from such civilisations, only sounding more fantastic then radio signals SETI was searching for.

Posted by: dvandorn Apr 14 2006, 10:49 PM

Ah, but what would such megastructures look like from interstellar distances? Dyson seheres would block out the light from the stars they encompass, so unless you see one being completed (i.e, the star just goes out), we wouldn't see them in the first place. Gravitational effects that would say a star should be in a particular place, but is not visible, could be explained by a dark neutron star or a black hole. And, again, there are other, far more likely explanations (dust rings, planetary nebulae, etc.) for megastructures that only partially or occasionally block the light from stars.

I also seriously doubt that anyone at our present level of civilization could even begin to model what types of ultraviolet, infrared, microwave or even X-ray signatures to look for that would indicate manipulations on a Kardashev scale. And such manipulations are probably going to look an awful lot like similar natural processes that end with the products these proposed engineers are trying to achieve. (In other words, if you're building planets, you're probably creating a situation that looks, from the outside, a lot like natural planet accretion. The only thing that might be different from a "natural" accretion scenario would be the timeframe, and we don't have a good enough handle on how long the natural processes take to be able to tell, from interstellar distances, that anything we see is happening at an accelerated rate.)

So, while what you say makes sense, we really don't have either the detection capability to see such things definitively, nor the intelligence or the context to be able to nuance the tell-tale signs we need to be looking for.

-the other Doug

Posted by: ljk4-1 Apr 14 2006, 11:02 PM

QUOTE (Toymaker @ Apr 14 2006, 05:41 PM)

I also would like to ask if anybody knows the an answer to the following issue(please do mind that I am no scientist ). If SETI worked on assumption that they are searching for Kardashev type civilisations engaging in high megascale construction and energy utilisation have they ever considered searching for signs of such civilisations other then radio ? Of course this is highly SF to the average person, but If they were assuming radio transmissions on such scale, why not search for Dyson Spheres, infrared signs of civilisations around other stars using high energies, megascale constructions etc ? After all It would fall into the same activity expected from such civilisations, only sounding more fantastic then radio signals SETI was searching for.

Posted by: Toymaker Apr 14 2006, 11:08 PM

Posted by: ljk4-1 Apr 14 2006, 11:27 PM

SETI is obviously not given the importance you claim it to have by others,
otherwise it would have a lot more funding and a lot more prominence in
the public's mind.

You must be reading some rather old SETI literature, as most SETI scientists
are not quite so "bold" about their pronouncements of finding alien life as
they may have have once been. Now that we know there are no powerful
signals being broadcast in our galactic neighborhood (at least by the methods
we can detect) - thanks to SETI - scientists are being more cautious and also
trying find them via other methods, such as Optical and infrared searches
for Dyson Shells.

Modern SETI started in 1960 with Project Ozma, but only in the last decade
has it really begun to get the technical and financial attention it is needed to
become any kind of a real success. Certainly trying to find out if there are
other intelligent beings in the Universe counts among the highest endeavors
for science.

No real SETI scientist thinks SETI will give us the ultimate verdict on intelligent
life elsewhere, but it does have a real chance of finding at least a few other
species, now that the searches are finally starting to go beyond a few sporadic
and temporary efforts.

And until the day comes that we can start sending probes out to other star
systems, SETI will be our best bet for finding them.

Looking for microbes in our solar system, finding alien planets around other
suns - it all adds up to the same goal.

Posted by: Richard Trigaux Apr 15 2006, 06:58 AM

Toymaker, an ever good policy when we search infos on a topic is to seek these infos at the source. In the instance, on the SETI website, not into bad science review which confuse SETI with some new age cult. Of course SETI searchers may have various opinions, and some may even have psychological defects (like everybody else) but I think we can say that, globally, the SETI search and the SETI community are good science. It is a bit incredible that, whatever we speak of medecine, astronomy, physics, electronics... people reply us about medecine, astronomy, physics, electronics... but when we speak about exobiology, we are replied psychoanalysis. It is as if, when Steve Squires presents us results of the Mars rovers, we asked him if he has a super-ego or a dogmatic vision of Mars. This is basically a stupid prejudice which should be absent on a science forum, but which has yet parasited half of this thread. THIS SHOULD STOP.

About your reflexions:

-The Kardanshev classification has three scales: type I: us. Type II: all the energy of a star. Type III: all the energy of a galaxy. What you was speaking about was type III. Type II and type I ar still far from reach of SETI. The diagram of the SETI results should answer your question: a type III should be detected wherever into the galaxy (none was found) a type III at maybe hundreds of lights years (none was found at this distance, teling us they are not common) and a type I at... less than 1 light year. None was found, but in this situation it is a bit unconclusive, don't you think so?

-Dyson spheres should radiate the same energy that they receive from their star, but at a much lower wavelength. At a rough guess the "surface" of a Dyson sphere should be somewhere between 0°C ant -50°C. So they may appear at "cold stars". As far as I know, astronomers never purposely searched for such objects, but they actively searched for infrared emitters into clouds, where stars form. There was also systematic sky surveys to try to peer through dense clouds. Unfortunately Dyson spheres would be confused with other stars. But I think that if there was a Dyson sphere nearby, it would be mapped for long, if not identified.

-Dyson spheres could also appear as "machos" in the search for dark matter. But again, we would be unable to distinguish them from a cold white dwarves. ("Machos" are star-like objects, supposed to form the bulk of the dark matter. Let us a bit speculate wildly: the dark matter would be formed of billions of Dyson spheres... ooops)

-About the models used by SETI (how civs may communicate, what by-products the emmit, etc...) there was in the beginning of SETI an enthusiasm on such naive "scifi" models as the Kardanshev models, which are now widely questionned. So some are theorizing on other wavelengths, other communication means, other purposes, other evolutions than the Kardanshev models. But this is still highly speculative and it is difficult to come with a testable assertion. So SETI is still doing what we know to do: exploring the radio spectrum (a task far from finished) and it begins to search for laser communications.

Posted by: ljk4-1 Apr 15 2006, 09:59 PM

William Edmondson has created a setiblog for updates and information on his
research into pulsars (rapidly rotating neutron stars) as beacons for SETI.

The Web site URL:

http://www.cs.bham.ac.uk/~whe/setiblog.html

From the introduction:

SETIblog

This blog is about the analysis of 3TB of radio-telescope data collected at Arecibo as part of a Search for Extra-Terrestrial Intelligence using a new targeting strategy reported in a journal article. The processing started shortly before Christmas 2005. Exploratory work of familiarization with the data format and some processing algorithms will eventually be followed by detailed reports on the data for each star studied.

The Web site has links to his papers on the subject as well.

Posted by: ljk4-1 Apr 17 2006, 08:01 PM

A Scheme for Targeting Optical SETI Observations

Seth Shostak (1) and Ray Villard (2)

(1) SETI Institute, Mountain View, CA

(2) Space Telescope Science Institute, Baltimore, MD

Abstract

In optical SETI (OSETI) experiments, it is generally assumed that signals will be deliberate, narrowly targeted beacons sent by extraterrestrial societies to large numbers of candidate star systems. If this is so, then it may be unrealistic to expect a high duty cycle for the received signal. Ergo, an advantage accrues to any OSETI scheme that realistically suggests where and when to search.

In this paper, we elaborate a proposal [1] for selecting regions of sky for intensive optical SETI monitoring based on characteristics of our solar system that would be visible at great distance. This can enormously lessen the amount of sky that needs to be searched. In addition, this is an attractive approach for the transmitting society because it both increases the chances of reception and provides a large reduction in energy required. With good astrometric information, the transmitter need be no more powerful than an automobile tail light.

http://rayvillard.com/science_papers.htm

Posted by: Bill Thompson Apr 18 2006, 10:02 PM

Getting a signal from an intelligence society would be the most exciting thing I can imagine for humankind.

But I wonder this. As we continue to look and as we keep finding ourselves putting more energies into new ways to look, at what point do we decide to direct more energies in other things like, for instance, super telescopes and the launching of intergalatic AI probes?

Another thing to consider is this. At what point to we decide to dedicate our time and efforts inward towards things like finding a cure for cancer rather than looking for a signal from space?

Posted by: Richard Trigaux Apr 19 2006, 10:17 AM

QUOTE (Bill Thompson @ Apr 18 2006, 10:02 PM)

Posted by: ljk4-1 Apr 19 2006, 02:05 PM

QUOTE (Bill Thompson @ Apr 18 2006, 06:02 PM)

Posted by: Richard Trigaux Apr 21 2006, 07:21 AM

QUOTE (ljk4-1 @ Apr 19 2006, 02:05 PM)

Posted by: dvandorn Apr 21 2006, 09:47 AM

Richard, nothing -- and I mean, absolutely nothing -- in the private sector world *ever* gets done without *any* positive cash flow. No one is ever going to put up a few hundred million dollars for a planetary probe just because they want to see what's out there. Not without some way of generating some income out of it.

Even if Falcon worked (which it has not, as of yet) and even if the Falcon developmental costs (suffering from little, seemingly unimportant expenses, like needing to launch six or seven of them before they get the bugs out, or building an oxygen liquifaction plant so they can actually launch the things without having to wrap them in blankets that flap back onto the thrust chambers and damage them) don't push the eventual costs of a Falcon launcher up into the same range as the currently available launchers, there are still a lot of significant costs you're overlooking. For example, the DSN isn't cheap. How are you going to command your private Enceladus probe, or get data back from it, unless you pay the $10,000 or more an hour that using the DSN costs? Gonna build a new DSN? If so, how are you going to make it cheaper than the current DSN (seeing as how, AIUI, the current DSN is already a private enterprise)?

There are *maybe* three people in the world who have enough money to do something like this, and even they can only do this once or twice, at most, without bankrupting themselves. Corporations simply will not undertake such missions, since there is no chance of ever generating any income from them to match the outflow, or even to pay for a tenth of the costs. Corporations simply do not spend out millions of dollars for no return.

It's a nice dream, Richard. But that's all it is -- a dream.

-the other Doug

Posted by: Richard Trigaux Apr 21 2006, 09:53 AM

QUOTE (dvandorn @ Apr 21 2006, 09:47 AM)

Posted by: Bob Shaw Apr 21 2006, 07:39 PM

otherDoug:

Dozens of OSCARs and CubeSats and Cosmos-1 demonstrate that there are other ways of working in space which don't require megabucks; as for the DSN, if an amateur can detect the carrier from Voyager-1, then perhaps something could be organised just for the fun of it.

Bob Shaw

Posted by: Richard Trigaux Apr 22 2006, 07:35 AM

[quote name= again, avoid quoting when replying to it
[/quote]


Not accounting with the fact that a carrier with a modulation is not the most energy wise way to send information by radio. Radio amateurs, who have to work with severe legal power restrictions, use for long ago more econompic modes, such as the old morse (the most efficient mean of all to send speech) or unique sideband transmition (called BLU in frnch, I don't know the acronym in english, something like SSM perhaps). In this mode the carrier (which... carries no information) is simply suppressed by a sharp filter, together with one of the sidebands, so that all the power is into useful non-redundant info.

Such smart ideas will not make a Cassini mission out of cardboard boxes and wooden planks, but if technical-wise amateurs and some sponsors unite to do something, they could prick some interesting bits. For instance the DSN relies on a small number of large dishes (only one being operating at a time on a given target) but many small amateurs antennas spread in the world could obtain some results too. Afterall, radio amateurs is a useless activity, just for fun. But a real purpose would add some more fun.

Posted by: Bill Thompson May 1 2006, 11:45 PM

I do not think that life on Earth is (for lack of a better term) a “natural” thing (there really is no such thing as “unnatural” and so I am limited by the English language to find a good adjective to use here). I think we are the result of extremely good luck. Now, before you dismiss this idea completely, I hope you will hear me out.

What I mean is this. For the first few hundred million years of life on Earth after microbes colonized into animal life, plants had not yet evolved. The life that existed on Earth was in a state of continuously consuming the oxygen supply. At this time life had not evolved on land either and if we were to go back in time and walk on the earth it would be difficult for us to breathe due to the high concentration of Carbon Dioxide in the atmosphere.

Fortunately, plants evolved and the Carbon Dioxide started to be converted into Oxygen.

Of all the fortunate events to have happened, this was the most fortunate. If this had not happened, life on Earth would have exhausted itself out of existence. I think normally in the universe life is like this. It is like a flame that flares into existence and then exhausts the resource it feeds on. Without any way to renew or replace the resource, it typically dies away.

In my mind, this is a pretty good explanation as to why we seem to be alone.

I think we are the result of the odds working out in our favor just the right way several times in a row like rolling the dice and the numbers coming up just right several times in the right order.

Posted by: dvandorn May 2 2006, 05:16 AM

QUOTE (Bill Thompson @ May 1 2006, 06:45 PM)

Posted by: Richard Trigaux May 2 2006, 08:45 AM

QUOTE (Bill Thompson @ May 1 2006, 11:45 PM)

Posted by: Toymaker May 4 2006, 02:21 AM

QUOTE (Richard Trigaux @ May 2 2006, 08:45 AM)

Posted by: PhilCo126 May 6 2006, 08:29 PM

Well, I guess most of the large Radio-dishes are quiet busy and getting time on them to conduct SETI would be difficult... Richard idea of going 'private' might work for a Radio-astronomy project.
On the other hand, it's great to know that the Deep Space Network antennes are being used, be it indirectly, by Spaceguard Survey, in order to give 3D images of NEar Earth Asteroids...

Posted by: Bill Thompson May 12 2006, 07:34 AM

QUOTE (Richard Trigaux @ May 2 2006, 08:45 AM)

Posted by: Richard Trigaux May 12 2006, 09:05 AM

Yes, plants are a difficult problem. Only an oxygen-rich environment can allow for muscles, neurones and generally large beings. An oxygen-poor world can only have some small worms and the like.

So on Earth the "precambrian explosion of life" 800-600 millions years ago was in fact the coincidence of two unrelated events:
-appearance of organized multicellular animals
-drastic increase in oxygen level, allowing for large animals, muscles, brain, etc.

In is all the more puzzling if we consider that photosynthesis existed since long before (at least two billion years-old stromatolithes) and was already providing oxygen. But the today oxygen level was achieved only recently (800-600 millions years ago). Why? Is it because early plants were not so effective? Or because the oxygen was absorbed by some sink, for instance large iron deposits? I don't know, and probably nobody knows.

Another curious coincidence is that plants and animals achieved multicellularity simultaneously. However the two lineages diverged billions years before. But is this sure? Are the stromatolites the ancestors of modern plants? Or did the bacteria, plants, mushrooms and animals diverged only a bit before the pre-cambrian life explosion? (In this case we must admit that photosynthesis appeared several times in different branches and at different ages).

So the simple vision of evolution of life as a linear series of steps gets a bit complicated, if several lineages are evolving simultaneously (plants and animals, both indispensible for intelligence) together with geochemical conditions (consuming oxygen sinks).

In a way, Bill, you are true that the need with such coincidence may make lose a factor ten, or more, in the Drake equation. Or, said in a more today way, the probability to find a civilization on a planet of a given age increases slowlier with this age, and is thus globally smaller.

Posted by: Thorsten May 12 2006, 08:56 PM

QUOTE (Richard Trigaux @ May 12 2006, 11:05 AM)

Posted by: ljk4-1 May 12 2006, 09:07 PM

I know the first comment to what I am going to say is "We work with
what we know", but perhaps we should start toying more with other
ways life - as we don't usually think about it - could exist on other
worlds, especially those that don't seem like very nice places at first.

Hey, we used to think nothing lived at the bottom of the oceans or
under miles of rock or in hot, hot acidic geysers, right?

I know Part 2 - but how can intelligent life come from those tough
little bugs in such nasty environments?

I don't know, that's why we need to search and run computer simulations
and think outside the box.

And for those who say But how can we communicate or learn anything
from beings so truly different from us?

So we stop searching just because some aliens might actually be ALIEN
instead of near clones ala Star Trek? It's called making bold explorations
and discoveries in science. Plus how can we learn anything new if we
just keep searching for guys like us?

Judging from the comments here and some of the more recent books on
the subject, I would say we are going through another negative phase in
our thinking about ETI. It comes and goes depending on the political
and social climate of the time and the progress (or lack thereof) being
made in SETI and astrobiology.

My thought on the subject is there's this amazing, dynamic and lively
(in numerous senses of the word) galaxy out there, but the majority of
the talking monkeys on Sol 3 are too busy focusing on their little problems
and thinking they are the focal point of the Cosmos to get out there and
really search for others in the Universe.

Posted by: Richard Trigaux May 12 2006, 09:24 PM

QUOTE (Thorsten @ May 12 2006, 08:56 PM)

Posted by: Thorsten May 13 2006, 05:15 PM

Salut Richard.

The energy generation of green sulphur bacteria is photosynthesis in its strictest sense. (Technobabble start: It contains bacteriochlorophyll, which is excited by the absorption of visible light and produces the electron gradient necessary to generate chemical energy, Technobabble end). It’s just not “powerful enough” to “split water” (this evolutionary breakthrough came later - with cyanobacteria and plants)). Of course, these bacteria need places where H2S as photosynthetic electron donor is obtainable; therefore – as you mentioned - a strong evolutionary pressure towards more easily available electron donors such as water existed.

Coming back to your question, why multicellular complex life emerged long after oxygen-producing photosynthesis was established. Indeed, organisms capable of responding to light (earliest photosynthesis) were found as early as 3,5 billion years ago (Warrawoona, Australia), only a few 100 million years after the end of the heavy bombardment phase. Stanley Miller estimated in the 1990s that some very primitive bacteria could have evolved in not more than a few tens of millions years out of prebiotic soup (which is heartening, when you think of the possibility of life in places like Enceladus).
Why then did it take so long for complex life to emerge?

I agree that the existence of continents might have played an important role – even today, the majority of marine species live in shallow-water regions close to the coasts, while the biological diversity in the deep sea is much lower. And since all ocean life is dependent on nutrients, which mostly come from the land as runoff from rivers and streams, the growth of the continents might have influenced evolution. Unfortunately, the growth of continents is the direct results of plate tectonics, which has proposed to be a key factor for life on Earth (including its function as global thermostat via the CO2-weathering cycle and its possible role for the generation of the Earth’ magnetic field). So, I guess, it’s kind of difficult to separate one from the other.

However, I believe that there is another important factor. Look at the enormous complexity of even the simplest modern day bacteria, the perfection of DNA damage repair after UV radiation or the precision of how genetic information is transcribed to proteins and passed on to the next generation. Without this elaborate machinery complex life would have never been possible. Take for example an especially sophisticated high fidelity nanomachine – the DNA polymerase (which copies the genetic information when the cell divides to become two cells). This nanomachine copies genetic information as fast as 1kb/ sec, and has an error rate of 1 bit/ 10e9 bits). A higher mutation rate would be deleterious for any organism, while a lower mutation rate would probably be unbearably expensive and very slow (since the proofreading of the nanomachine consumes a lot of chemical energy). Interestingly, it has been assumed that this protein directly affects the complexity of all life on Earth. DNA polymerase makes around 3 mistakes each time a human cell divides, which allows all humans to pass accurate genetic instruction from one generation to the next, and also to minimize the chance of harmful changes in somatic cells that would lead to cancer.
However, although the mutation frequency in complex life forms is low, it is nevertheless thought that the limit of the number of essential proteins that any organism can encode is 60’000 (humans have 30’000). If the mutation frequency was for example ten times higher this would have limited an organism to about 6000 essential genes. In that case evolution would have probably stopped at an organism less complex than a fly.

In summary, the generation of a simple reproducing system is probably easy, but the incredible perfection of complex life might have taken a long time.

Thorsten

Posted by: Richard Trigaux May 14 2006, 08:34 AM

Thanks for your very interesting reflexions, Thorsten.


Until recently, what I was thinking is that what took many time for evolution, from very early bacteria to multi-cellular organism, was precisely the capacity to encode, not only the infos for the cell itself, but also for the body organization. This capacity appeared slowly, first with the capacity for cells to exchange chemical messages and undertake specific chemical activities accordingly. Then appeared the capacity for cells to move relative to each other, stick together, etc. What produced the pre-cambrian explosion of life forms was probably the capacity of having the organism form itself coded into DNA, with the series of gens known as homeobox, which work with an hormonal gradient (from head to tail) and reacts after the various concentrations to form the various body segments. There was an early evolution testing many kinds of symmetries, until the bilateralians won (this was already discussed before in this thread).

The appearance of multicellularism produced a huge increase in genome size, and further the appearance of complex organs produced another order of magnitude in genome size. Think for instance that simply the smelling sense counts for 10% of the rat genome, as each smell has to be recognized by a special molecule. The complex brain circuitry too consumes a lot of genentic resources.

So, as you noted, this can work only with an efficient nanomachine like the DNA transcribers (I could not imagine they were so fast). It is clear that poorly performing nanomachines would severely limit the complexity of living being (and, as you note, we humans are about at 50% of the limit, and we must pay the cost in terms of cancers and genetic diseases).

The questions are, if we want to explain all this in a multi-path chain of events, which was the order of events, their overal probability?

-Was the appearance of efficient nanomachines the cause of complexification of life, or did this complexification appeared much later, arising slowly from difficult problems to solve? Or did simply the efficiency of the nanomachines increased steadily to cope with the complexity of their task?

-Complexification and multi-cellularism appeared simultaneously in plants and animals, when it seems that their lineage separated much sooner. But I am not sure of this: what is the exact evolution tree for ancient plants (stromatholites, cyanobacteria), modern green plants, animals? Could only a relatively recent single event before the precambrian explosion of life (like the appearance of an efficient nanomachine) have triggered all what we see today? Or had we really two independent evolution paths (animals and plants) which had to solve the same problems (nanomachines, complexity, multicellularism) and solved them in about the same time? This later question is especially interesting in an astrobiology scope, as animals and plants had separated genetic evolutions, as if they were on two different planets.

The vision I defend in this thread of a series of random steps (the duration of each step being the inverse proportion of its probability) gets more complicated, as passing each step depends of many "small" events. This makes a more continuous flow of events, but this flow can still be fast or slow according to the difficulties it has to solve.

Posted by: ljk4-1 May 15 2006, 05:06 PM

Methane-belching Bugs Inspire A New Theory Of The Origin Of Life On Earth

http://www.science.psu.edu/alert/Ferry5-2006.htm

12 May 2006 --Two laboratories at Penn State set out to show how an obscure undersea microbe metabolizes carbon monoxide into methane and vinegar. What they found was not merely a previously unknown biochemical process--their discovery also became the inspiration for a fundamental new theory of the origin of life on Earth, reconciling a long-contentious pair of prevailing theories.

This new, "thermodynamic" theory of evolution improves upon both previous theories by proposing a central role for energy conservation during early evolution, based on a simple three-step biochemical mechanism.

Posted by: ljk4-1 May 15 2006, 07:50 PM

This paper sounds rather relevant to the most recent discussion here:

Evolution of Photosynthesis and Biospheric Oxygenation Contingent Upon Nitrogen Fixation?

Journal-ref: International Journal of Astrobiology, vol. 4 (3 & 4): 251-257, Oct. 2005

http://arxiv.org/abs/astro-ph/0605310

Posted by: Richard Trigaux May 16 2006, 08:21 AM

Thanks ljk4-1 for once again posting interesting references.


To summarize the quoted article, the appearance of modern and efficient photosynthesis, not only depends of the ability to decompose water itself, but also to the ability to fix nitrogen (to form proteins, as in modern agriculture). Only a set of several conditions allowed efficient photosynthesis (they say between 0.5 to 2.5 billions yeras ago) despites the fact that photosynthesis existed since much more time (stromatholites, 3 billions years or more).

So, between the appearance of the first bacteria (likely between 4 or 4.5 billions years ago) and the appearance of evolved life (multicellular + efficient photosynthesis + oxygen + brains) 0.6 to 0.8 billions years ago, there was a long and slow process where several important and independent steps had to be overcome without help from each other:
-efficient photosynthesis
-nitrogen fixation
-exhausting oxygen sinks (iron, etc)
-homeobox gens system
-etc

And this process took roughly 3 billions years, during wich life on Earth was limited in protected places and played only little geochemical role.

So we can hypothetise, as many insisted in previous posts, that the gathering of so many independent conditions, could explain that evolved life appears only after billions years, in such a way that we could be really among the firsts. And on many planets, the life conditions would become unfavourable before evolved life appeared.

Once again we have an explanation of the Fermi paradox, as some pages ago with the story of the gamma ray bursts able to sterilize a galaxy. But they showed much less dangerous, and only into ancient galaxies. So nothing is sure yet. We have to wait to be able to look at the spectra of many Earth-like planets and look for evidence of photosynthesis.

Posted by: ljk4-1 May 16 2006, 02:08 PM

QUOTE (Richard Trigaux @ May 16 2006, 04:21 AM)

Posted by: Bill Thompson May 17 2006, 01:54 PM

From my personal experience I can conclude that there are politics in this science.

I think that if a scientist or engineer looks at all the available information and concludes that it might be more likely that there are currently no creatures in the galaxy like us, he is probably going to be quiet. This would be and is an unpopular view. It is unpopular not because it is wrong. It is unpopular because it is not as exciting.

I wonder if anyone would agree with me.

Then again, I might be all wrong and I need to go back and study some more and different information. I will have some free time in June. I will make use of my vacation.

Posted by: ljk4-1 May 17 2006, 02:24 PM

QUOTE (Bill Thompson @ May 17 2006, 09:54 AM)

Posted by: djellison May 17 2006, 03:05 PM

What happened to scientific curiosity, exploration and boldness?

Easy...

Their budget got cut.

Ask Joe Public if he wants to spend vast swathes of money looking through a haystack for a needle that we may or may not be able to detect and which may or may not even exist - and he'll say no - it's a waste of money - and you have to admit, it's a perfectly valid point of view.

The finding of life in this solar system is clearly an important goal within space agencies across the world - but it costs an enormous ammount of money so it has to be done frustratingly slowly.

Finding life elsewhere - imho SETI is going to come up blank however long you try. The maths just doesnt add up as far as I'm concerned. The haystack too large, the needle too small, our eyes not powerfull enough.

However - programs such as TPF, Lisa etc - programs dedicated to finding the sorts of bodies around the sorts of stars at which would be familiar to us - again, are interesting and worthwhile exercises. Let's search in a sensible way - lets get that first spectra of an earth like body around a sun like star and find what's going on. Carefully, systematically, intelligently looking for interesting things 'out there'.

But at the end of the day - go and say to 1000 members of the general public "We need to search, pure and simple" - they're going to ask why...what good would it do them? And they have a point, they really do.

SETI may be a bold and important and honourable thing to some, but to many it's just pointless nonsense.

Doug

Posted by: ljk4-1 May 17 2006, 05:42 PM

But neither you nor Joe Public have to extract any of the tiny fraction
of your income taxes that once went to NASA's brief flirtation with SETI in
the early 1990s for the projects running now (and being British, you never
had to pay any amount for SETI). And they are all still much less
expensive than your average space probe.

I could equally make a case that Joe Public does not understand,
appreciate, or support sending vehicles to other worlds. After all,
they're just a bunch of rocks and ice in space, right? What could
we do with those? And shouldn't the money be better spent to
alleviate the problems right here on Earth?

Don't you just love that last phrase. Billions spent every year on
poverty, pollution, crime, etc., but they seem to still be here. Ah
well, we still shouldn't be sending rockets to Mars, anyway.

As for SETI being foolish and pointless, in addition to the already
mentioned inexpensiveness of the endeavor (which once again I
will state is not related to space probes and NASA has now shown
how little they really support even astrobiology), I wonder how the
various real scientists, engineers, and investors who have supported
SETI over the years would response to such labels? If you ever look
at who is in the SETI field, you won't find many crackpots and others
of the type associated with UFOs et al.

I have never thought that SETI would be easy or brief. I am thinking
of the long term investment for humanity and science. Since it is not
impossible that someone might be trying to signal us, or that we might
pick up a stray transmission, spending a few bucks on a few telescopes
to watch the skies isn't a crime or a waste of time, at least to those who
do this type of activity. Just because it isn't in "vogue" with some doesn't
make it less viable. Science isn't (or shouldn't be) a fashion trend.

To me the real crime is that there may be ETI out there trying to make contact
or at least broadcasting, and we miss it. That will probably make the nay-
sayers and religious types happy, though. We wouldn't want to learn
anything new from a different perspective.

I guess this is what happens when one has grown up in a more optimistic
age and am now living in a more conservative and inward-looking one.

The final point: Space probes, SETI - they are all about exploring the
Universe and improving our understanding of it. Joe Public usually does
not make a differentiation between the two. Since our goals have many
similarities, it is a shame to have to be at odds when both fields are
exploring space (and I happen to support both very much).

Posted by: Bob Shaw May 17 2006, 06:47 PM

'Joe Public' probably has a better take on SETI than the academics do - it's simple to understand as a concept, and culturally most people are prepared to accept that other intelligent life exists (although often in a Star Fleet uniform!). If you then go on to explain how cheap most forms of SETI are, then questions start getting asked about expensive science...

...and if any formal test of public support for SETI is required, then just look at the SETI at home phenomenon - 'Joe Public' got involved just because it was a cool thing to do...

Bob Shaw

Posted by: djellison May 17 2006, 07:22 PM

QUOTE (ljk4-1 @ May 17 2006, 06:42 PM)

Posted by: ljk4-1 May 18 2006, 12:23 PM

I have long had this bad habit of assuming that those who are into the
subjects I like - in particular, astronomy and space exploration - are into
all aspects of the field. But reality jars me loose from that preconception
often enough.

Perhaps it all began back when I was young (cue sad violin music), where
I grew up in an isolated town where no one I knew was into space, particularly
like I was. And aliens - might as well just be accused of being a witch, even
after the first Star Wars film came out.

Back then, I was thrilled when I found anyone who liked any aspect of my
interest, even if they only watched Star Trek. I naively assumed that if they
were into Star Trek, they must also be into space and astronomy (cue slowly
rising sad violin music, with a little piano thrown in). But sadly, I learned
that while they thought Mr. Spock and phasers blowing up starships were
really cool, most of these same people couldn't have cared less about real
space probes going to Mars or starships or SETI or the Sun as viewed with
a hydrogen alpha demulsifier.

So I grew up, moved away to the big city for my first real job, and discovered
that even though there were actual people who liked space and astronomy,
they still looked down on SETI. Maybe it was because it isn't something
that provides instant gratification. Maybe they saw Aliens one too many
times. Maybe they were abducted. Who knows?

But... I understand now. Everyone likes their own thing, and just because
it has something to do with space does not mean they are into it or accept
it. I understand now.

So, go on... go on with your deep space probes to alien worlds with your
instant gratification and the really cool photos of craters and geysers and
rocks. I'll be alright, really. I'll be the one just quietly sitting up on some
grassy hill on a cool evening, looking up at the stars... and wondering.

And while I'm up on that hill, I'll also be looking at my 8x10 glossy photos
of the Himalayas I always carry around with me, because, some day, I'm
gonna climb those mountains. I swear.

Cue crescendo music. Fade to black.

For Carl.

Posted by: BruceMoomaw May 18 2006, 02:22 PM

Okay, but when they land on that hill one night, carry you off and start sticking that long pointed thing into you, don't say I didn't warn you...

Actually, I've always had a gigantic soft spot for SETI. It seems to me that, where space-related research is concerned, its ratio of cost to potential benefit is almost unmatchable, and the stupefying scientific ignorance shown by the Congressmen who keep slapping it down (most of them Democrats, alas) is simply infuriating. Given that the program could be more than adequately funded for just a few tens of millions of dollars out of NASA's annual budget, this is one space project I definitely feel the government should get back into. (To quote Woody Allen: "It should be kept in mind that when scientists talk about 'life in outer space' they are frequently only referring to amino acids, which are never very gregarious, even at parties.")

Posted by: djellison May 18 2006, 02:44 PM

I am not against the actual process of hunting for life 'out there' far far FAR from it, but I fail to see the potential benefits in basically, standing in the solar system with a hand cupped behind one ear.

Call it CIOESPFH (arguably the greatest acronym ever made )- Catalogue and investigation of extra solar planets for habitability. That's what I think is the sensible course of action if we're going to realistically find out who our neigbours are, or if we even have any. Maybe that's still 'Seti' - but just a different way of doing it.

It's an embarrasment that we don't know what numbers to put into Drake's equation...you can quite comfortably get anything from 10^-10 to 10^10 without even touching the boundries of feasability. Let's spend money filling out the blanks.

Doug

Posted by: ljk4-1 May 18 2006, 03:48 PM

QUOTE (BruceMoomaw @ May 18 2006, 10:22 AM)

Posted by: ljk4-1 May 18 2006, 07:48 PM

QUOTE (djellison @ May 18 2006, 10:44 AM)

Posted by: djellison May 18 2006, 08:36 PM

I wasnt advocating the dispatching of probes to other stars, I was suggesting it's better to do a systematic study of them from here, to find out what sort of planets there are, how many there are, getting some spectra of them - find out how many habitable places there might be...hell, find out how many habitable places there in our own back yard might be a good start. We don't even know how many times life started here...and we're trying to find it out there?

Doug

Posted by: ljk4-1 May 18 2006, 08:48 PM

QUOTE (djellison @ May 18 2006, 04:36 PM)

Posted by: BruceMoomaw May 18 2006, 10:20 PM

QUOTE (ljk4-1 @ May 18 2006, 03:48 PM)

Posted by: Toymaker May 18 2006, 11:00 PM

Posted by: dvandorn May 19 2006, 04:59 AM

QUOTE (djellison @ May 18 2006, 03:36 PM)

Posted by: edstrick May 19 2006, 07:59 AM

The British Interplanetary Society's "Daedelus" interstellar probe study project, published around 1980-82, clearly establishes interstellar travel is possible. They basically did an engineering-requirements study of a two stage electron-beam-inertial-fusion powered unmanned flyby of the Barnard's star "system", being the second closest extrasolar star system. The vehicle would travel at 0.15 the speed of light, arriving without slowing down, in about 40 years. Payload was a hubble-sized telescope with a comprehensive package of planet search and study instruments.

Basically, it requires an early but expanding solar-system based civilization to be able to afford and do it. It's very "not trivial" but clearly within the reach of plausible and physically permissable engineering.

Posted by: Richard Trigaux May 19 2006, 08:25 AM

Hi all,

thank you for this interesting confrontation between opinions.

Personally, I don't believe that we MUST engage into a method and MUST not into another. SETI shows much more difficult than expected 50 years ago, but should it provide only one result, this result would be about intelligent life, not just about amino acids which we know are nearby everywhere.

What you propose, Doug, making a statistical and exhaustive study of all the planets we can detect, is very interesting too. In doing so, we work at the begining of the evolution chain, but we work on the same evolution chain than SETI. Filling the blanks in the first terms of the Drake equation will certainly help to understand what happen to the last term, and perhaps solve the Fermi paradox. So why not to undertake a search on this subject rather than on SETI? Simply because SETI we know to do, and the search of extrasolar planets we are just beginners. We are still unable to find earth-sized planets into the inhabitable zone, and all the more to make a statistics of planets. Of course we must increase the effort on the search of planets, as only a statistics of complete solar systems (not just large freak planets) will allow us to really understand the formation of planets and predict the first terms of the Drake equation.

At a pinch, SETI could lead to unexpected results, even in the case it never detects any ET signal. For instance its constantly improved sensitivity could allow us to detect planets by their natural radio emissions (magnetic activity, MASERs) and thus obtain irreplaceable infos on their atmospheres and chemistry.

What we could try, for instance, would be to observe a given star with the mask methods used into gamma ray telescopes, or the reverse of the spectrum-speading methods used to hide a radio channel into noise. This would (perhaps) lead to a several magnitude increase into the sensitivity of radio receivers.





At last, when speaking of ET life, inevitably come the jokes on UFOs and abduction. I don't want to start a discution on these subjects (that I consider seriously, of course after filtering all the rubbish) but I would like to say that I more and more disagree with the idea of these phenomenon being the activity of ET spaceships. My opinion is rather that those phenomenon (especially abduction) are something else. Especially most abduction reports seem in fact experiences of sleep paralysis, a curious phenomenon experienced by some 10% of people, which show us characters or other feelings, often sexual. But sleep paralysis seems closer to a dream experience than to anything else... Sleep paralysis (nightmare in our grandparent's language) don't explains everything, and especially scientists studying UFOs will not admit that a dream experience can produce the physical effects they demonstrated. What I want to say here is that these phenomenon are certainly curious, but I think they belong to the exploration of human consciousness rather than of space. Interesting, but another topic. I just feel incredible that, in our science age, there is still a large majority of people as naïve as in the Middle Age, when their sleep paralysis showed them "demons" (that they called incubus and succubus) and they believed they were real!! There is nothing to be afraid in the affair, and especially there is no kind of conclusion to draw about real ETs, what they could be or what they could do. To summarize into a science paper language, UFO and abduction reports, even considered as sincere testimonies, don't pose any kind of constrain on ET life or ET behaviours.

Posted by: BruceMoomaw May 19 2006, 11:33 AM

Regarding Doug Ellison's fondness for TPF: keep in mind that it will be an EXTREMELY long time before humanity ever manged to send probes to even the nearest stars -- if we ever do -- which means that virtually all we'll be able to learn about any life-bearing planets circling other stars for centuries or more will be (if we're lucky) a little bit about the general biochemistry of their dominant photosynthetic organisms. And this, by itself, will cost billions --or tens of billions -- of dollars. Now consider the fact that even the most elaborate SETI networks proposed cost only a few hundred million -- and consider the impact on humanity of discovering proof of another intelligent race, as opposed to just discovering the existence of photosynthetic life on another world. Which is more scientifically an culturally 'cost-effective"? One guess. Moreover, the same reasoning applies to the very expensive search for evidence of past ormpresent microbial life elsewhere in our own Solar System.

I think we should be spending money on all three of these things -- but if it came down to a choice, I would unhesitatingly go with SETI as the best of the three searches.

Posted by: djellison May 19 2006, 11:41 AM

Here's a thought. How much energy and time have we spent sending out signals that would be detectable by the same equipment with which we listen for signals, and at what range would they be detectable, and what statistical chance would an observer looking at a random part of the sky have of hearing them.

i.e. if there was another 'us' out there...would they be able to hear us and would we hear them.

Doupg

Posted by: climber May 19 2006, 12:00 PM

[quote name='djellison' date='May 19 2006, 01:41 PM' post='54905']
Here's a thought. How much energy and time have we spent sending out signals that would be detectable by the same equipment with which we listen for signals, and at what range would they be detectable, and what statistical chance would an observer looking at a random part of the sky have of hearing them.

i.e. if there was another 'us' out there...would they be able to hear us and would we hear them.

Doupg you mean "doubt", don't you ?

Posted by: Bob Shaw May 19 2006, 01:08 PM

QUOTE (djellison @ May 19 2006, 12:41 PM)

Posted by: ljk4-1 May 19 2006, 02:33 PM

This online article, "Detectability of Extraterrestrial Technological Activities"
by Guillermo A. Lemarchand, worked out the details of how far various
electromagnetic signals could be detected over interstellar distances:

http://www.coseti.org/lemarch1.htm

Lemarchand also examined optical, x-ray, and neutrino radiation, among
other concepts.

As for finding terrestrial-type exoplanets in a fashion that may be less
complex than the TPF, see the New Worlds Imager (NWI) concept:

http://casa.colorado.edu/~wcash/Planets/new_worlds.pdf

http://www.astrobio.net/news/article1226.html

One method for finding ETI could involve astronomical objects that just
about any society which practices astronomy and has at least our level
of technology could detect and utilize: The powerful natural beacons
known as supernovae (pulsars and GRBs may also work in this idea).

See here for the details:

http://www.iar.unlp.edu.ar/SETI/GAL-Scient-Ame.pdf

http://www.iar.unlp.edu.ar/SETI/seti-boston.htm

Posted by: Bob Shaw May 19 2006, 02:49 PM

Here's a good set of ranges from the paper by Guillermo A. Lemarchand (link 1 above):

ARECIBO PLANETARY RADAR

TARGETED SEARCH

Unswitched
With CW detector 4217 MAXIMUM RANGE (light years)
With pulse detector 2371

Switched
With CW detector 94
With pulse detector 290


SKY SURVEY

Unswitched
With CW detector 77

Switched
With CW detector 9


BMEWS

TARGETED SEARCH
Pulse transmit CW detector 6
Pulse transmit pulse detector 19

SKY SURVEY
Pulse transmit CW detector 0.7



Not so far, really...

Bob Shaw

Posted by: ljk4-1 May 31 2006, 06:14 PM

The Park hypothesis
---

Human spaceflight opponent Bob Park and the Search for
Extraterrestrial Intelligence (SETI) do not appear to have much in
common. Michael Huang proposes a hypothesis, based on Park's
arguments, which could explain SETI's greatest mystery.

http://www.thespacereview.com/article/629/1

Posted by: Richard Trigaux May 31 2006, 07:39 PM

QUOTE (ljk4-1 @ May 31 2006, 06:14 PM)

Posted by: ljk4-1 Jun 1 2006, 03:24 PM

The Case for Transmitting to Space

http://www.space.com/searchforlife/seti_transmit_060525.html

When talk turns to SETI, there's one question that's as common as catfish:

"We're not broadcasting to the aliens; so what makes you think they'll be
broadcasting to us?"

Posted by: ustrax Jun 1 2006, 03:51 PM

QUOTE (ljk4-1 @ Jun 1 2006, 04:24 PM)

Posted by: ljk4-1 Jun 2 2006, 12:10 PM

Some thoughts on alien ways of thinking:

http://www.centauri-dreams.org/?p=679

“Advanced societies throughout the galaxy probably are in contact with one another, such contact being one of their chief interests. They have already probed the life histories of the stars and other of nature’s secrets. The only novelty left would be to delve into the experience of others. What are the novels? What are the art histories? What are the anthropological problems of those distant stars? This is the kind of material that these remote philosophers have been chewing over for a long time…” — Philip Morrison (1961)

“Will we be able to understand the science of another civilization?… Our science has concentrated on asking certain questions at the expense of others, although this is so woven into the fabric of our knowledge that we are generally unaware of it. In another world, the basic questions may have been asked differently.” — J. Robert Oppenheimer (1962)

Posted by: ljk4-1 Jun 2 2006, 05:41 PM

The SETI Institute is having its own Open House on June 10, 2006:

Celebrating Science of the Future

An interactive science faire for the entire family

Join us at the SETI Institute on June 10, 2006 from 10 am to 4 pm for a celebration of science and imagination.

Learn about the SETI Institute's pioneering exploration of life, our solar system, and beyond, including the search for signals from other civilizations, as well as astrobiology.

Meet SETI Institute scientists, see what the future holds for SETI and astrobiology, participate in fun interactive activities like creating your own alien, and more.

The details are here:

http://publish.seti.org/celebrating%20science%20emailer.html

Posted by: Richard Trigaux Jun 2 2006, 08:20 PM

QUOTE (ljk4-1 @ Jun 1 2006, 03:24 PM)

Posted by: Richard Trigaux Jun 2 2006, 08:32 PM

QUOTE (ljk4-1 @ Jun 2 2006, 12:10 PM)

Posted by: ljk4-1 Jun 3 2006, 12:18 AM

QUOTE (Richard Trigaux @ May 31 2006, 03:39 PM)

Posted by: Myran Jun 3 2006, 10:05 AM

Posted by: BruceMoomaw Jun 3 2006, 05:25 PM

QUOTE (ljk4-1 @ Jun 3 2006, 12:18 AM)

Posted by: dvandorn Jun 3 2006, 06:12 PM

I totally agree with that last quote. If you want to get *really* scared, watch the opening sequence from the original series, "Connections." It demonstrates, almost viscerally, how vulnerable our modern technological society is to minor breakdowns in the daisy chain that keeps everything moving forward.

This is one reason I tend to say that, in order to survive this (hopefully) transitional period between dwindling energy and resources into a period of much cheaper and more plentiful energy (and thus the ability to get to hard-to-reach resources), we're going to need to use every tool at our disposal. Every resource, every scheme.

That's why I can't side with the Greens, for instance, in their desire to reduce our dependence on technology. We're *way* too far down the road for that. If we are to survive, we need to use every dreg of technology we can possibly dream up... at least, in my humble opinion.

-the other Doug

Posted by: Bill Thompson Jun 3 2006, 10:13 PM

QUOTE (BruceMoomaw @ Jun 3 2006, 05:25 PM)

Posted by: helvick Jun 4 2006, 01:22 AM

QUOTE (Bill Thompson @ Jun 3 2006, 11:13 PM)

Posted by: Richard Trigaux Jun 4 2006, 07:17 AM

QUOTE (helvick @ Jun 4 2006, 01:22 AM)

...Richard might well point out that that means I have some spiritual leanings after all.

Posted by: DonPMitchell Jun 4 2006, 08:59 PM

Seti is a fascinating project, even if it produces a negative result. Finding life in our galaxy would be a profound discovery. And if we are the only intelligent technological species, that is pretty damn profound too.

Personally, I think high-technology civilizations are rare. Anyone can play the game of plugging guesses into Drake's Equation, and when I do it, I get 0.1 civilizations in our galaxy. I'm not surprised that no radio signals have been found.

I'm a fan of Evolutionary Psychology, which suggests some speculations about intelligence in general. First, it is tricky to maintain a social species. The "Free Rider" program is lethal, so any successful social species must have a solution to that or it will evolve into a non-social species. That is, you have to eliminate criminals, slackers and cowards from the gene pool, or you're doomed as a species. It suggests to me that the more highly cooperative a species becomes, the tricker it is for them to remain viable for a long period. Look at H.G. Wells' story of The Time Machine, with its amazing concept that different economic classes might evolve into different species. Who knows how long a cooperative high-tech-capabile species even remains biologically stable?

Evolutionary Psychology also suggests that high intelligence evolves, not to solve problems of competing against Nature, but to solve problems of sexual politics and competion with the species. All this makes me thing that an alien intelligent species will not remotely look like us, but their atttiudes and personality may be similar to ours (just as pack animals such as dogs have easily recognized emotional attitudes, similar to our own). That could be good news or bad news!

Posted by: Bob Shaw Jun 4 2006, 09:06 PM

Don:

If the Dogoids come to Earth to have sex with our furniture, that's certainly bad news; still, it could be worse - they could be interested in our legs! Eeek!

Bob Shaw

Posted by: helvick Jun 4 2006, 09:55 PM

QUOTE (DonPMitchell @ Jun 4 2006, 09:59 PM)

Posted by: DonPMitchell Jun 5 2006, 12:24 AM

I loved Peter Hamilton's books. But I don't think a hive species would become intelligent, because there is much less sexual competition. Look at how extremely primitive the nervous systems of all Earth-based hive species are.

And consider how smart Dolphins are. But their intelligence evolved to solve sexual politics and did not generalized to complex manipulations of their evironment. They just have a lot of sex and eat a lot of fish. Not saying that's a bad thing. But maybe our species is a freakish aberation.

Posted by: ljk4-1 Jun 5 2006, 02:22 AM

QUOTE (DonPMitchell @ Jun 4 2006, 08:24 PM)

QUOTE (Bill Thompson @ Jun 3 2006, 06:13 PM)

What I wanted to say was this. I think that given all available information, we are, for all practical purposes, most likely the only folks like us in the galaxy. Or am I wrong?

I think there is movement of chemicals out there in all sorts of wierd arangements (is this, "life" ? ), but the only place I can get up, walk across the street to the 7-11 and buy a slurpee is right here.

Posted by: ljk4-1 Jun 5 2006, 02:18 PM

The economic alien
---

People continue to seek explanations for why evidence of
extraterrestrial civilizations continues to elude us. Gregory
Anderson suggests that the odds of detecting such civilizations
depends on their economic acumen as much as their technological
prowess.

http://www.thespacereview.com/article/633/1

Posted by: ljk4-1 Jun 6 2006, 03:33 AM

The current issue of Skeptic Magazine has an article entitled:

"ID & SETI: Can Intelligent Design be Considered Scientific in
the Same Way that SETI is?" by Robert Camp

It is not available online, but here is the magazine's Web site:

http://www.skeptic.com/the_magazine/index.php

Posted by: Richard Trigaux Jun 6 2006, 06:09 AM

QUOTE (ljk4-1 @ Jun 6 2006, 03:33 AM)

Posted by: ustrax Jun 6 2006, 09:35 AM

They're among us!

http://www.cnn.com/2006/TECH/science/06/02/red.rain/index.html

Very good discussion on this topic...

Posted by: Richard Trigaux Jun 6 2006, 10:03 AM

QUOTE (ustrax @ Jun 6 2006, 09:35 AM)

They're among us!

http://www.cnn.com/2006/TECH/science/06/02/red.rain/index.html

Very good discussion on this topic...

Posted by: ustrax Jun 6 2006, 10:07 AM

QUOTE (Richard Trigaux @ Jun 6 2006, 11:03 AM)

Posted by: ljk4-1 Jun 6 2006, 01:19 PM

QUOTE (Richard Trigaux @ Jun 6 2006, 06:03 AM)

Posted by: ustrax Jun 6 2006, 01:50 PM

QUOTE (ljk4-1 @ Jun 6 2006, 02:19 PM)

Posted by: Richard Trigaux Jun 6 2006, 04:03 PM

<side remark>We rely on CNN to know what happens in Irak and somilar topics. If they are not serious about ET life, how can they be serious about Irak? (assuming of course that ET life is obviously much more important than war)</side remark>

QUOTE (ustrax @ Jun 6 2006, 01:50 PM)

Thank you ljk4-1.
Is there any thread already discussing the Wow! Signal?
I didn't want to disrupt the rythm of this conversation that is being very interesting so maybe it is better to start a new topic on it. Or not...

http://en.wikipedia.org/wiki/Wow_signal

Posted by: dvandorn Jun 6 2006, 10:32 PM

QUOTE (Bob Shaw @ Jun 4 2006, 04:06 PM)

Posted by: ljk4-1 Jun 7 2006, 08:16 PM

Study Shows Our Ancestors Survived Snowball Earth

Seattle WA (SPX) Jun 07, 2006

It has been 2.3 billion years since Earth's atmosphere became infused with enough oxygen to support life as we know it. About the same time, the planet became encased in ice that some scientists speculate was more than a half-mile deep.

http://www.terradaily.com/reports/Study_Shows_Our_Ancestors_Survived_Snowball_Earth.html

Posted by: Richard Trigaux Jun 7 2006, 08:41 PM

QUOTE (ljk4-1 @ Jun 7 2006, 08:16 PM)

Posted by: ljk4-1 Jun 8 2006, 03:43 AM

Astrophysics, abstract
astro-ph/0606102

From: Milan M. Cirkovic [view email]

Date: Tue, 6 Jun 2006 01:01:04 GMT (858kb)

Macroengineering in the Galactic Context: A New Agenda for Astrobiology

Authors: Milan M. Cirkovic

Comments: Contribution to "Macro-Engineering: A Challenge for the Future" ed. by Viorel Badescu, Richard B. Cathcart, and Roelof D. Schuiling, in press

We consider the problem of detectability of macro-engineering projects over interstellar distances, in the context of Search for ExtraTerrestrial Intelligence (SETI). Freeman J. Dyson and his imaginative precursors, like Konstantin Tsiolkovsky, Olaf Stapledon or John B. S. Haldane, suggested macro-engineering projects as focal points in the context of extrapolations about the future of humanity and, by analogy, other intelligent species in the Milky Way. We emphasize that the search for signposts of extraterrestrial macro-engineering projects is not an optional pursuit within the family of ongoing and planned SETI projects; inter alia, the failure of the orthodox SETI thus far clearly indicates this. Instead, this approach (for which we suggest a name of "Dysonian") should be the front-line and mainstay of any cogent SETI strategy in future, being significantly more promising than searches for directed, intentional radio or microwave emissions. This is in accord with our improved astrophysical understanding of the structure and evolution of the Galactic Habitable Zone, as well as with the recent wake-up call of Steven J. Dick to investigate consequences of postbiological evolution for astrobiology in general and SETI programs in particular. The benefits this multidisciplinary approach may bear for macro-engineers are also briefly highlighted.

http://arxiv.org/abs/astro-ph/0606102

Posted by: Richard Trigaux Jun 8 2006, 05:41 AM

1) SETI did not failed. It simply did not detected large or intentional signals (sent to us) into a very limited bandwidth (around the water line). But it would be still unable to detect Earth-like planets (unintentionnal activity) at more than... 1 light-year. This makes that there is still plenty of place to search (increased sensitivity, larger bandwidth) and tens of years of enhancement ahead before being able to positively state that there is no radio technology out there.

2) The previous result arises suspicion on finding large technologies, precisely. So the authours should not conclude that we must search mainly such technologies, right on the countrary.


The SETI results today teach us one thing (if only one) that ET civs (if there are) are not what we expect in science fiction books. Eventualy Earth-like civilization would very probably be a very brief episode into the evolution of a planet. Earthlings only 2500 years ago would have be completely unable to predict our technology achievements, and even less our spiritual achievements (democracy, abolition of slavery, abolition of physical punishments, equalitarian laws, school for all, international peace keeping...) So how could we be able to extrapolate our achievements in 10 million years? Certainly this evolution is not linear, we shall not simply increase our technology level while keeping to a cold war political level, there will certainly be sharp turns or very unexpected steps.

Posted by: deglr6328 Jun 8 2006, 05:58 AM

QUOTE (Richard Trigaux @ Jun 8 2006, 05:41 AM)

Posted by: Richard Trigaux Jun 8 2006, 06:17 AM

QUOTE (deglr6328 @ Jun 8 2006, 05:58 AM)

one does wonder occasionally about the nadwidth of extraterrestrial life.

Posted by: ljk4-1 Jun 8 2006, 04:57 PM

QUOTE (Richard Trigaux @ Jun 8 2006, 01:41 AM)

Posted by: DonPMitchell Jun 8 2006, 05:58 PM

QUOTE (Richard Trigaux @ Jun 7 2006, 10:41 PM)

Posted by: ustrax Jun 8 2006, 06:55 PM

QUOTE (DonPMitchell @ Jun 8 2006, 06:58 PM)

Posted by: ljk4-1 Jun 9 2006, 08:43 PM

Reminder:

SETI Institute Open House

515 N. Whisman Road
Mountain View, CA 94043

June 10, 2006

10am – 4pm

Web site:

http://www.seti.org/celebratingscience2006/

For more information visit us online at www.seti.org (http://www.seti.org/) or call 650-961-6633 and ask for Cynthia Ramsayer.

Scheduled Talks

10:30 am "SETI: Science Fact, Not Fiction" - Jill Tarter
11:00 am "What Might E.T. Look Like?" - Seth Shostak
11:30 am "Europa: The Ocean Moon" - Cynthia Phillips
12:00 noon "ATA: Sharing the Sky" - Peter Backus
12:30 pm "A Home Away from Home: The Search for Planets around Other Stars" - Andrew Fraknoi
1:00 pm "Meteor Showers and Their Parent Bodies" - Peter Jenniskens
2:00 pm "Talking with E.T." -- Doug Vakoch
2:30 pm "What Might E.T. Look Like?" -- Seth Shostak

Meet and mingle with scientists

Frank Drake
Peter Backus
Devon Burr
Andrew Fraknoi
Friedemann Freund
Peter Jenniskens
Cynthia Phillips
Seth Shostak
Jill Tarter
Douglas Vakoch

Take a virtual tour of Hat Creek and the Allen Telescope Array.

Posted by: ljk4-1 Jun 13 2006, 03:25 PM

In the May.June, 2006 issue of The Planetary Report:

We Make It Happen! The Planetary Society Optical SETI Telescope

With the support of Planetary Society members around the world, The Planetary Society Optical SETI Telescope began searching the skies for signs of intelligent life in April. Planetary Society Director of Projects Bruce Betts explains the cutting-edge technology that will allow this unique SETI telescope to conduct a year-round, all-sky survey.

http://planetary.org/programs/planetary_report.html

Posted by: Stu Oct 17 2006, 04:16 PM

Anyone heard what today's "Major SETI Announcement" is all about? Nothing on the wires...

Posted by: ustrax Oct 17 2006, 04:22 PM

QUOTE (Stu @ Oct 17 2006, 05:16 PM)

Anyone heard what today's "Major SETI Announcement" is all about? Nothing on the wires...

Posted by: Stu Oct 17 2006, 04:28 PM

Thanks, but that's what I knew already... it still doesn't say what the news actually is... I wasn't expecting an announcement of a detection, I just want to know what's ging on...

Edit: Ah... just unearthed this on a SETI forum:

The announcement is regarding the formation of the Carl Sagan Center for the Study of Life In the Universe. The SETI Institute was the first to study astrobiology, under the mantle of simply The Center for Study of Life In the Universe (we call it LITU). Whenever an astrobiologist, astrophysicist, planetary geologist, etc said they worked for the SETI Institute they had to explain that they do not study radio astronomy. So, the management decided to create the Carl Sagan Center, with it's own logo, business cards, etc, that will better portray their range of study. The new logo took the central 'sphere' from the SETI logo and inserted Carl Sagan Center, I think it's pretty cool.
There are reports that NASA will be slashing funding for astrobiology by 50%, to fund the Moon and Mars human missions. We need to continue robotic and telescopic research to find microbial life in our solar system and extrasolar systems. We hope the new Carl Sagan Center will create new funding avenues.
This news is very exciting for us here at the Institute, but will probably disappoint those who were looking for something more dramatic.

Posted by: nprev Oct 18 2006, 04:31 AM

Well, that's good--if not exciting--news.

SETI is important, of course, even if the results are forever negative. If we found even ONE civilization intentionally broadcasting for detection (which seemingly is the fundamental attribution bias of SETI research), that datum would have enormous probable statistical implications...I mean, we don't do it, nor in my opinion are we ever likely to over the span of time required to garner the slightest hope of success, so why should anyone else?

Given that, I am afraid that if we survive long enough to conduct actual interstellar exploration (UM or MSF), we may well stumble upon some worlds in which the native intelligent species killed itself off as a result of failing to master many of the same daunting challenges our species faces today.

I believe that life is common throughout the Universe; I submit that wisdom and foresight may not be.

Posted by: nprev Jan 16 2007, 02:58 AM

Resurrecting a thread...looks like a passive (i.e., not relying on intentional transmissions) SETI detection instrument is about to start up. This seems like the smart way to go, imho.

http://planetary.org/news/2007/0110_SETI_Researchers_Propose_Eavesdropping.html

Posted by: MarkG Jan 17 2007, 03:57 AM

Posted by: nprev Jan 17 2007, 04:36 AM

I think you're right; that is a very fundamental question, but a great deal of supplementary data is needed to formulate a meaningful answer.

We have no actual evidence that the evolution of life itself is an inevitability, much less intelligence. We are lucky to live in the first period of human history where at least some sort of relevant statistical constraints on these questions may be derived, and that is the real value of projects such as Seti@Home.

Fermi's Paradox is valid, but only if a multitude of ancillary assumptions/hypotheses are also valid. This fact in itself may well prove Fermi's idea...unless we disprove it ourselves by colonizing the galaxy!