For reasons completely unknown to me, people who know nothing whatsoever about the ancient Mayans and, indeed, could not care less about the ancient Mayans think that the world ended yesterday. I had serious doubts, so I pinched myself and listened to the weather forecast before deciding that the world had not ended yesterday. My wife told me to shut up and go to sleep.
But when will the world end? That depends, of course, on what you mean by the world ending. If you mean when will Earth itself be destroyed, then that will happen roughly 5 billion years from now, when the sun becomes a red giant. Notice that I said 5 billion years, with a B, not, thank God*, a mere 5 million years, with an M.
If you mean, when will life on Earth be obliterated, that will happen in a more disquieting 1 billion years.
More practically, Science Illustrated magazine, on whose arrival I reported here, ran an amusing piece in the January-February, 2013, issue: the 10 greatest threats to humanity. Among those threats, several could presumably wipe out humans entirely: a massive comet (every 32 million years) or an asteroid (every 500 thousand years) hits Earth, a supervolcano (could be any day now) such as that buried under Yellowstone National Park explodes, Mars crashes into Earth (because the planetary orbits are not truly stable), or – here is a really good one – a 10-second burst of gamma rays from a hypernova (whatever that is) burns off the ozone layer and destroys the food chain. Fortunately, a hypernova seems to be only slightly more likely than the Mayan prediction. (Incidentally, an asteroid will pass inside the orbit of a geostationary satellite in 2013 but will not hit Earth – this time.)
That’s 5, provided that you count comets and asteroids separately. The remaining threats are a massive pandemic due to natural or synthetic diseases (that’s 2), robots and nanorobots (that’s 2) do us in, and, finally, nuclear war does us in. I was somewhat surprised that they did not mention anthropogenic global warming, which, along with nuclear war, is my candidate.
I count 5 bangs and 6 whimpers – for whatever that is worth.
* Figuratively speaking, that is.