[X] My Assistant

[deglr6328]

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.

[edstrick]

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.

[Guest_Richard Trigaux_*]

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.

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 from one extreme rather than from the other.


Red dwarves have other 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.