[X] My Assistant

[ljk4-1]

Science/Astronomy:

* The Growing Habitable Zone: Locations for Life Abound

http://www.space.com/scienceastronomy/0602...table_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.

[ljk4-1]

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

[Marz]

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

So if the last big extiction event was the cretacious 64mya, that means we should be right on the edge of a transition to the intergalatic frying pan? Yikes! Where'd I put my suntan lotion?

I remember one strange thing about the cretacious extinction event that seems to have been caused by a bad case of 'roids, was that some marine species had begun to die off before the 'roid hit. So maybe the 'roid just kicked us while we were already heading down?

[Guest_PhilCo126_*]

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

[ljk4-1]

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

The Wow! Signal of 1977 was certainly not pre-SETI. Modern SETI is marked by Frank Drake's Project Ozma in 1960:

http://www.planetary.org/explore/topics/se...history_04.html

And the famous Morrison-Cocconi paper in Nature in 1959:

http://www.coseti.org/morris_0.htm

And even though it was downplayed by mainstream SETI scientists until about 1998, Optical SETI can also mark its modern origins to a 1961 paper in Nature written by Schwartz and Townes, the latter being the inventor of the laser:

http://www.coseti.org/townes_0.htm

FYI - Albert Einstein advocated using intense light beams for communicating with celestial neighbors in 1937. He considered aiming the lights at Mars, but still, he was thinking of Optical SETI way before it became trendy.

[Guest_Myran_*]

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.

[ljk4-1]

Science/Astronomy:

* Sharing the Allen Telescope Array

http://www.space.com/searchforlife/seti_at...kus_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.

[ljk4-1]

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

[ljk4-1]

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/set...tical_searches/

[ljk4-1]

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.

[ljk4-1]

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/

[Bill Thompson]

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. found it) 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.

I had SETI@HOME on my computer until I read about Fermi's Paradox. I think his observation made sense and since it made sense I could not see any civilization sending us a radio signal in our galaxy. So I removed the screen saver.

I think that, sadly, SETI is only confirming what was obvious to Fermi and what we do not or cannot believe to be true.

I think there might be life out there. I also think that the benefit of finding the life will be huge. But I think it is mostly microbes. This still means to me that the benefit will be huge when we find it.

Science/Astronomy:

* The Growing Habitable Zone: Locations for Life Abound

http://www.space.com/scienceastronomy/0602...table_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.

But what about the requirement of pressure for water to exist? Water is a result of both temperature and pressure.

Also, what about the requirement of metals? Without our metal core we would not have a magnetic field (Mars and Venius lack the magnetic fields and thus are bombarded by radiation).

I wonder if the article you link to discredit this one:
Refuges for Life in a hostile Universe from Sci. Am.

[Bob Shaw]

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

[ljk4-1]

I wonder if the article you link to discredit this one:
Refuges for Life in a hostile Universe from Sci. Am.

I am very suspicious of anything written or supported by G. Gonzalez,
as he is pro-Intelligent Design and co-author of the book The Privileged
Planet, which essentially states for theocratic reasons that Earth is the
only world in the entire Universe with life and that the Universe itself
was made just for humanity's use.

As for not being contacted by ETI, it is possible that most alien life is
no more advanced than microbes, but with 400 billion stars in our
galaxy alone, how can you or anyone presume that ETI would even
know we exist to contact or stand out in any way when our electromagnetic
signals have barely traveled 100 light years into a galaxy that is
100,000 light years across?

To add another data point to the field, this recent paper discusses how
GRBs seem to occur more with galaxies that are low in metallicities -
though I presumed that galaxies with low amounts of metals would not
be terribly suitable for life to begin with; unless someone had already
stripped mined the place.

http://xxx.lanl.gov/abs/astro-ph/0604113

[Guest_Richard Trigaux_*]

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).