Why theano UFOs

On May 12, 2008, at 3:29 PM, sailor.barsoom wrote:
> It does seem that the Fermi Paradox has only two possibilities:
>
> 1) We don't see aliens because they are hiding.
> 2) We don't see aliens because there aren't any.
>

Right. SETI proponents claim (3) we just haven't looked hard enough,
but I don't buy that. A spacefaring civilization could settle the
whole galaxy within a couple hundred million years. That's peanuts
compared to the timescale of evolution. So if they're out there, they
settled the galaxy long ago, and would know darn well that we're here.

> Number 2 of course divides into three more:
>
> 2a) There aren't any because they never evolved in the first place.
>
> 2b) They evolved, but destroyed themselves before they could meet us.
>
> 2c) They're are out there all right, and they haven't destroyed
> themselves, but they never advanced technologically to the point of
> space travel/radio astronomy. There's no reason any society HAS TO
> get past the paleolithic, much less the industrial.
>

That about covers it. These are all variations on the same idea
though, which is that a civilization has to pass successfully through
a number of probability filters in order to develop to the point where
space travel (and communication) becomes possible. Some of those may
be in our past, like the initial formation of living cells (your 2a),
and some may be in our future, such as survival of the discovery of
that seductive but planet-smashing technology we don't realize we're
pursuing (formation of mini-black holes or whatever).

There was a really good essay on this in the latest Technology Review,
where the point was made that the more complex life we discover out
there (whether on Mars, Europa, etc.), the more depressed we should
be, because that implies that the Great Filter that destroys all
species before they colonize the galaxy is in our future, rather than
in our past. If it's in our past, no worries, we got lucky or we
wouldn't be having this conversation. But if it's in our future,
there is no reason to suppose we'll be any luckier than anyone else.

So here's fingers crossed that Earth life remains the only life we
ever discover! :)

Best,
- Joe