The Milky Way has, at last count, about two hundred billion stars. Billions of them are G-type main sequence, the same as our sun. Which means they are stable, with long lives. Estimates about terrestrial worlds suggest they too are in substantial numbers. So there should be a lot of other intelligent beings. Which brings us to the Fermi Paradox.
Enrico Fermi was an Italian-born physicist. He won the Nobel Prize in 1938 for his work with neutrons and radioactivity. He was one of the leaders of the team that put together the atomic bomb in 1944. So, he famously asked, if we are surrounded by billions of places that seem reasonable sites to produce intelligent life, where is everybody? We’ve been watching, and listening, for decades, and so far everything is quiet. There is no indication, other than occasional UFO reports, that there’s anyone else out there.
During my years writing science fiction, I’ve had the opportunity to discuss the issue with a good many astronomers and physicists. Is it likely there are aliens? Or are we probably alone? Most of us, whose science is largely limited to SF, have no doubt there are aliens. We’ve seen too many on Star Trek, read too much Bradbury, experienced too much Star Wars. If I tell a crowd of SF readers that there probably are no aliens, they usually become annoyed. The notion of an empty universe isn’t very appealing. But ask physicists and astronomers and the vast majority express the opinion that we are probably alone. If there’s another intelligent species anywhere, one physicist told me recently, it’s probably in Andromeda.
I’ve been around long enough that the opinion no longer comes as a surprise. But it’s still a bit disappointing. Although many of the best minds on the planet will argue that, if we really are alone, it’s good news.
We don’t seem to know yet how life gets started. The odds against its appearance at any given location may be so high that it’s only going to show up in one or two places in a galaxy this size. Or it may be that intelligent beings get into loud arguments and destroy themselves before they can do much else. We came close in 1962 during the faceoff near Cuba between American and Soviet vessels. The Soviet ships were accompanied by four submarines, armed with nuclear weapons. The Kremlin had given the sub commanders authority to defend themselves with the nukes if necessary.
The confrontation became serious and the issue came down to whether to use a nuclear torpedo, which would probably start an atomic war. The commanders on one submarine were in favor of doing it after being depth charged. But Vasili Arkhipov, the senior commander, said no. Fortunately for us all.