How and When Will the World End? The Atlantic asked a variety of thought leaders. I liked this answer from nuclear scientist Taylor Wilson:
“I think it’ll be what we don’t see coming—a killer asteroid, a nearby gamma-ray burst, or a solar event. All the better reason to become a spacefaring species!” (emphasis added)
http://www.theatlantic.com/magazine/archive/2013/07/how-and-when-will-the-world-end/309400/
