Astrobiology “Alive and Well,” But Should We Hope the ETs Aren’t?

May 2nd, 2008

Space.com reports on AbSciCon2008, with a story by Edna DeVore claiming that “Astrobiology Alive and Well.”   She describes a quality meeting of the astrobiology community, with a lot of young faces, turnabouts in funding cuts, and a promising, growing future.

At the same time this is going on, with the astrobiologists all excited about the search for life on other worlds, Nick Bostrom wrote a very sobering article for Technology Review explaining why he hopes they fail.     He’s doesn’t make a religious argument, or seem to be an anti-science guy in any way.   He hopes they fail because he wants to be hopeful about humanity’s chances of beating extinction.

His argument is based on circumstantial evidence and probabilty, but still quite worth considering.   The first bit of circumstantial evidence involves the idea known as Fermi’s Paradox.   Physicist Enrico Fermi was fond of making back-of-the-envelope estimates that were very often correct.   The classic estimate he did that led to the “paradox” was one in which he determined that even with slower-than-light interstellar travel, it wouldn’t take cosmologically long times at all for an intelligent technological species to send probes all over the Milky Way.   Whats a few tens of millions of years in the face of a universe billions of years old already?   The fact that we don’t see evidence of alien technology (UFOs nonwithstanding) means that they’re not there.   Fermi asked, “Where is everybody?”

The answer to the paradox is that Fermi made some incorrect assumption.   The simplest solution is that other extraterrestrial intelligences don’t exist in our galaxy, although there are many others worth exploring (Stephen Webb offers 50 solutions in his interesting book Where is Everybody?).

If there are no other intelligences out there locally as implied by the simplest solution to Fermi’s Paradox, that makes advanced techological civilizations extremely unlikely.   The argument is then that there’s some “great filter,” some step leading to such civilizations, which is unlikely.   It can be a difficult positive step, like the development of life at all, or multicellular life, or an easy negative step difficult to avoid, like managing not to destroy ourselves with our technology.

We’re not quite at the stage at which we can fill the Milky Way ourselves, so then have we already managed to get through the filter, or is it still ahead of us?

Bostrom would like to think that we’ve already gotten through the filter, that life arising at all, or advanced life arising from simple life, is the tough step.   Failing to discover life on Mars and in space in general would mean it’s hard to do, and might be the filter.

Otherwise, if life is common beyond Earth, the filter might still be before us, and the silence that SETI finds would mean that civilizations have reached our level of technology many times before, but never much farther.   Presumably because they’ve destroyed themselves.

There are other possibilities, but without a lot of data, it’s a probability game and this one has some merit.

I personally don’t feel that it’s right.   I mean, it could be, in some sense, but I think that the sum of all the other possibilities is more likely than this one particular suggestion, and there’s a lot of quantitative wiggle room.   As the searches of all types continue, we’ll learn more to assess this issue.

And hey, even if life isn’t common and we are unique, don’t get depressed about it.   There’s still a good chance we’ll rise to the challenge and destroy ourselves!   Just give us a chance…or start worrying about it now and prioritize space travel.   Getting off this planet is our best insurance.

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