I’m not sure I buy Davies’ argument from the previous post. There’s lots of potential big steps that might have taken less time than anticipated. Why the origin of life? Why not the origin of eukaryotic cells, multicellular animals, life on land, big brains? Why did those things all take a long time? The most straightforward answer is that those things are hard. If life’s origin is hard, too, then why didn’t it take at least a while to start here?
Even so, I agree with Davies (and Ward and Brownlee), about complex life, and intelligent life. I think it is very rare, so rare that we might be the only one.
I’m persuaded by Fermi’s Paradox: “where are they?” We’re talking here about intelligent life that, at least in some cases, must be many millions, even billions, of years old. If they were there, I believe we’d know it. Maybe not every intelligence would make their presence known, but it only takes one. It’s an old, old universe, and we just got here. Where is everybody else?
We can imagine a universe in which extraterrestrial intelligent life is obvious. We’d look up in the sky, and we’d know. Clearly we don’t live in that kind of universe. There are two potential reasons. One, they’re not there. Two, they’re there, but no one’s doing anything we’d recognize across the light years. Not one? In millions, even billions, of years? Really?
You can, of course, think of lots of scenarios explaining why we seem to be alone even if we’re not. But they are all special pleading. The most straightforward explanation for us seeming to be alone is that we are.
Some people might find this depressing, and I admit, I’d love for us to discover other intelligences. Just a single discovery could change everything tomorrow. I hope it happens. Assuming it doesn’t, though, I’m not so sad about the alternative. If we really are alone, then we have a huge universe that is ours and ours alone. We are the eyes and ears of that universe. Let’s see what we can learn.