End of the World

Why haven't I made this post before?

Because I was preoccupied with tastier topics, I think. And exploding cars.

How many times has it been predicted that the world will end?

Thank you, Internet! A zillion times is the technical term, here is a semi-exhaustive history of the apocalypse .

By whom?
Are there secular doomsayers?

The only certain secular end time is the explosion of the sun. I've already mentioned the concept of Malthusian catastrophes , which is the big secular end of the world, but there may be some nutty New Agers who think the world will end but aren't overtly religious.

What could actually cause the end of the world?

Well, there is the explosion of the sun in around 4.5 billion years. Of course, you also have the gray goo scenario, where out-of-control nanobots eat the whole world. Or Ebola might mutate into a pandemic form and we all die. Or WWIII occurs and you get an On the Beach gone with a whimper type end of the world.

On a happier note, you could just have the world change so far as to be utterly unlike the current world, the "as we know" it line.

How likely are those events?

The explosion of the sun is certain. 1.0. Will happen. It is, however, inconceivable! that it would happen in the near future. I don't know about the rest at present.

What could theoretically be done to prevent said events?