SETI again

On Jul 21, 2006, at 15:33 UTC, Robert wrote:

> someone has to be the first race. we cant rule out that we are the
> first.

Of course. That boils down to the "there's nobody else out there" answer, and makes sense only if the evolution of technological life is exceedingly rare and difficult.

In my opinion, that is one of only two reasonable possibilities (the other being that we're in some sort of nature preserve, and our keepers will clearly introduce themselves when they're good and ready).

> also we cant rule out that if there is one faster, that it is
> so far away the evidence of it will not reach us for a million years.

We pretty much can. If we're not the first, then probably whoever was first was at least millions of years ahead of us -- more likely billions. They would have had plenty of time to colonize the whole galaxy by now.

I did some detailed calculations on this a while back and found that, under certain generous assumptions, it was just possible for 2 or 3 civilizations (of billions that would eventually evolve) to achieve spaceflight before the first one filled up the galaxy. But it was unlikely; far more common is for the first one to be considerably ahead of civ #2. This is because at the tail ends of a normal distribution, individuals tend to be quite far apart.

Best,
- Joe

Joe Strout -- joe@...