Why SETI may be a dead end., page 1
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reply posted on 11-8-2004 @ 03:25 AM by robertcd
I am absolutely certain that intelligent life must have developed elsewhere in the Universe, and probably very frequently. BUT, assuming Einstein was right, and nothing travels faster than light, I'm also absolutely certain that we will never communicate with any species outside our own solar system. It's all a matter of time and probability. The distances between stars (let alone galaxies) are too vast and the time spans too great for us to be aiming our radio telescopes in the right place and listening at the right time.

Electromagnetic radiation (light, heat, radio etc) doesn't "bounce around" in space as Gazrok suggested. It travels in a straight line, except where it's bent around objects with mass such as stars, galaxies or black holes. So we won't hear anything unless we point our scopes right at the source.

We often focus on the space factor but not the time factor in considering the possibility of encountering radiation from an alien civilisation. It takes 10^9 to 10^12 years for radiowaves from 99.9999-I don't know how many more 9's-% of the universe to reach Earth. We've been transmitting for less than 100 years, and listening for less than 50. It seems pretty unlikely we will survive as a technologically advanced race for many more hundreds of years before BLAM - either we destroy the place or it destroys us! At the rate the oil price is going maybe we'll soon have to cut right back on technology anyway. Alien civilisations will most likely encounter all the same problems we have, living on a self contained and self sufficient ball of matter.

So, multiply all these miniscule probabilities together and the chance of contacting aliens is something similar to the possibility of locating a single grain of sand on a beach by chance - it's never going to happen! Pretty bleak truth, but I'm big enough to live with this - why are so many people afraid of it?

Professor Bob


reply posted on 11-8-2004 @ 04:13 AM by Genya



reply posted on 11-8-2004 @ 05:34 AM by Genya
Originally posted by robertcd
It's certainly a noble cause Genya, though I would prefer to be using the resources to find all those big chunks of space rock out there that will eventually wipe us out if we don't look sharp! Prof Bob


Thank you for your kind comments Bob!

Of course, discovering NEO's is extremely important to us (although just *what* we'd *do* if one was found to be heading for Earth is still a mater of conjecture I think?). Obviously, resources that might be used for this "radar" serach of near space is imperative.However, in the case of SETI@home, which uses the
Arecibo radio telescope, the receiver effectively "piggy backs" whilst the telescope is surveying the sky for other projects.

Quote from here

"Like Project Phoenix, the SERENDIP receiver is based at the Arecibo Observatory, but unlike Phoenix it doesn't need to wait (my emphasis) for highly-prized observation time-slots. Instead, it is permanently perched above the Arecibo dish, scanning whichever part of the sky the dish happens to be pointed at and moving through the sky with the rotation of the Earth. While this approach would not work for a targeted search, it is well suited for an all-sky survey like SERENDIP."

As an aside - or extension to the discussion - the same reference above discusses Optical SETI - quote:

"The Planetary Society has also branched out beyond radio searches, sponsoring Optical SETI ventures that look for concentrated laser signals from the stars. In 1998 it began supporting two targeted searches, based in Harvard and U.C. Berkeley, which look for very short light bursts coming from candidate stars. Since the end of 2000 The Society has supplemented these projects by funding the construction of the largest dedicated Optical SETI observatory in the world, in Harvard, Massachusetts. When completed ometime in 2002, the observatory will be used for the first all-sky Optical SETI survey."

Still looking and listening!!


reply posted on 11-8-2004 @ 05:42 AM by Quest
The drake equation is great if we had any basis to fill in number, but we don't.

One of the more disturbing things to come from identifying extrasolar planets is that virtually every star we look at has a gas giant in close orbit to it. Why is this bad?

A gas giant in close orbit would tear apart or consume any small rocky world like earth. Our solar system works well for life because the gas giants are set out far from the sun. So not only are there no gas giants crushing the earth, but they are also collecting debris from larger orbits.

But the more we look the more it starts to look like our solar system is more of the exception than the rule. Our model of solar system formation has always been based on our solar system, but the more we look to other stars the more it would seem we are wrong.

Here is the drake equation based on current real estimates (based on data) of the involved numbers:

R= 1 (Rates of the birth of sun like stars)
Fp= 1 (Generous assuption planets form around all stars)
Ne= 0.0001 (Generous asuption that stars we aren't sure about do have earth-like planets)
Fl= 1 (No basis for this number so assuming life will developes every where it can, big leap)
Fi = 1x10^-22 (out of all species on earth only one, us, have become intelligent/technological)
Fc = 0.00001 (based on the time we've been communicating with radio since we developed language)
L = 4 million (based on the avergae lifetime of a species on earth)

All those number based on what we know of life yields 0.0000000000000000000000004 species in the milkyway for us to talk to.

So the drake equation, based on what we know rather than what we hope for, actually say there IS NOT anyone out there. So until we have some new data, the drake equation is an argument AGAINST SETI.

Now I support seti because out understanding of the universe it too limited to trust those numbers. But nonetheless, the drake equation is an argument against looking, not for it.


reply posted on 11-8-2004 @ 06:12 AM by Genya
Originally posted by Quest...One of the more disturbing things to come from identifying extrasolar planets is that virtually every star we look at has a gas giant in close orbit to it....

...Now I support seti because out understanding of the universe it too limited to trust those numbers. But nonetheless, the drake equation is an argument against looking, not for it.


Hi Quest!

Thank you for your comments and analysis of the Drake equation, as well as the discussion about extra-solar planets. According to
this source there are 110 such objects, although as the site was only updated on 3rd March 2004 I don't know if any more objects have been discovered? I've just done another search which found 108 planetary systems, 123 planets, and 13 multiple planet systems (from here dated 22nd July 2004. I guess the more we look, the more we'll discover??

As regards the Drake equation - well, at best it *is* a "guestimate" and open to all sorts of specualtion as regards what numbers to input. I included it merely because of it's "historical" significance, and for others to do their own analysis if they so wish?

However, I don't see how this mitigates against SETI? Surely if we "listen" or "look" - because we have the technolgy to do so at this moment in our technological development - then we should?? Even if the Drake Equation argues against the existence of other civilisations (by inputing numbers that give low estimates, for example) surely an objective of science is to observe the Universe in both the micro- and macrocosm?

Finding *one* extraterrestrial civilisation by SETI could be the "white crow", don't you think?
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