I’d reconciled myself to the fact that the sun will die in about 5 billion years — time enough to get all the important stuff done, I thought — but now Chris Mims tells me we’ve only got 12 million years. I mean, that’s like going to the doctor, and he says, “Good news, Mr Myers, you’re going to live to be 90” and then he calls you up a little later and says “whoops, little slip up there, you’ve got a month to live.” It’s not good news.
The story is a bit speculative—we’ve long known that there are these very rough periodic extinctions in the fossil record, and now a few wild-eyed theoreticians suggest that it might be correlated with our system’s rotation around the galaxy, and every 60 some million years we swing around to the side that’s getting zapped a little more heavily.
Just to throw a little restraint into the guesswork, though, the mass extinction data shows considerable variability, and also the idea that we’re going to get irradiated is a little excessive. Passage through the rough side of the galaxy would be an event spanning millions of years: the earth was not sterilized in previous events, but if this were the cause, it would mean that there would be a low level increase in radiation over a very long period of time that would have stressed life to varying degrees. We do have 12 million years to manufacture lead-lined umbrellas and try to develop cosmic-ray resistant wheat. I’m just going to have to trust my great600000th-grandchildren to get their act together in time.