What I’m reading
Contact by Carl Sagan. It’s a novel (his only one?), now apparently out of print, about contact with extra-terrestrial intelligence. I’ve decided to start a process of discarding books I’m never going to read again, and I recall finding this one a bit disappointing the first time I read it, so it’s a candidate for the recycle bin. I’m only a couple of chapters in, and it starts off well enough, so maybe I’ll keep it.
This got me thinking about SETI in its various manifestations. It’s of interest as a distributed computing project, but I don’t know much about that side of things. More relevantly, I think the fact that nearly all the visible sky has been searched for radio signals, with no result, leads to some interesting and disturbing thoughts. A useful place to start is the (in)famous Drake Equation, which might be better referred to as the Drake Identity.
I won’t spell out the details, except to say that I think we can now assert, with high confidence that there are many planets (billions) and very few radio-using civilisations (probably none within thousands of light years of us).
One implication that is fairly solid, I think, is that, either intelligent (radio-using) life arises extremely rarely (say once per galaxy) or interstellar travel is impossible. Otherwise some species would have colonised some planet in our neighbourhood. Either way, it seems certain that we will never have either physical contact or meaningful two-way communication with any other species.
The other implication is that radio-using civilisations either don’t arise often or don’t last long. I tend to favor the first implication. Even now, it would probably be possible for humans to set up a radio beacon in space that would last more or less indefinitely, and would serve as a permanent memorial if we managed to blow ourselves up (or back to the Stone Age). But even with civilisations lasting 100 000 years and arising on thousands of planets in our galaxy, the chances of actual contact (say, two civilisations existing simultaneously within 100 light years of other) would be minuscule.
fn1. In reference to planets a thousand light years away, it would be more precise to say that there were none a thousand years ago.