In the next decade or so, I expect humanity to discover whether the same forces that gave rise to life on Earth exist on other worlds as well.

If we find that they do, then the fact that we haven’t discovered intelligent life on other worlds (or rather, that they haven’t revealed themselves to us) is rather worrisome.

Here’s why: humanity is developing several technologies that could conceivably wipe our entire race out. I’m thinking specifically of custom-engineered viruses, but experiments in super-hot plasma and miniature manmade black holes are worrisome too.

Now if life arises naturally everywhere in the universe, the question is, where are the other sentient races? My fear is that the natural progression of technology is such that, around the time a race develops weapons of mass destruction, someone somewhere loses control of theirs. Poof. Another civilization gone, around about the time they would have made contact with the others.

One encouraging sign, though, is that we haven’t seen any debris left by prior advanced civilizations on Earth. If there had been one, we’d have seen something by now. But what if planet-eating black holes or plasma or self-replicating nanomachines are the culprit on other worlds? Those wouldn’t allow future races (or any life) to evolve on the same planet twice.