Why theano UFOs

--- In spacesettlers, Joe Strout wrote:

> 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.

Yeah. Maybe I should have listed 3). But I tend to agree with you: a
galactic civilization should be pretty obvious. In fact, I'd go so
far as to say the 3) is actually a subset of 1), as in: if there is a
galactic civilization out there and we have to look that hard to find
it, they're hiding.

>> 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).

This whole thing suggests that whoever makes it first has most or all
of the galaxy to itself before anybody else comes along. Perhaps what
is "inevitable" is that some civilization gets there first and then
ruthlessly stomps on anybody else who becomes capable enough to make
them nervous (but before that anybody else becomes capable enough to
give them a fight). Of course, a civilization like that might well be
expected to hide...

> 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.

An interesting idea. Not sure I buy it, but right now I can't think
of any real argument against it.

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

Which is depressing in its own way.