Why theano UFOs

On May 13, 2008, at 12:39 AM, Dan Wylie-Sears wrote:
> It seems possible that the great filter is mostly a matter of time and
> distance. A spacefaring civilization has no particular claim on
> lasting a million years, let alone a hundred million. There's time for
> species to have evolved, but there's also time for species to have
> evolved into dead ends where they were too specialized to meet the
> next
> hurdle.
>

Like what? Once you have a spacefaring civilization at all, it's
going to have tremendous diversity. What would cause all those
diverse people to universally stagnate?

Their universal destruction (for example, by destroying the entire
region of space that contains them) seems much more plausible to me.

> Maybe the great filter is a dilemma. Species that maintain mixing
> across their entire range evolve as one species, and come to a dead
> end
> one way or another; species that don't maintain mixing across their
> entire range don't spread enough across the lightyears to keep up with
> the extinction of local populations every few thousand years.
>

That doesn't make any sense either. "Species" in the biological sense
is probably not a useful concept for a technological society, but
quite regardless of whether you call them one species or thousands,
there will always be some more advanced and adventurous than others.
Those continue to expand; the stay-at-homes stagnate; but on the
whole, the spread across the stars would be continuous.

> Or maybe different species evolve, make contact, and annihilate each
> other after periods of peaceful coexistence averaging only 10,000
> years.
>

Annihilate each other? It's hard to see how this could happen unless
(A) both civilizations happen to evolve at exactly the same time (on a
geologic time scale), or (B) there is some plateau of possible
technology that is reached before contact is made. Otherwise, it's
very hard to explain how the second civilization could destroy one
that's millions of years older.

But, maybe. That would be an example of the Great Filter being in our
future. (Though I still think something that affects each
civilization individually, such as the discovery of some particularly
dangerous technology, is far more plausible.)

Best,
- Joe