By then the sun will have shrunk to a white dwarf, giving little light and even less heat to whatever is left of Earth, and entered a long, lingering death that could last 100 trillion years—or a thousand times longer than the cosmos has existed to date. The same will happen to most other stars, although a few will end their lives as blazing supernovas. Finally, though, all that will be left in the cosmos will be black holes, the burnt-out cinders of stars and the dead husks of planets. The universe will be cold and black.

But that's not the end, according to University of Michigan astrophysicist Fred Adams. An expert on the fate of the cosmos and co-author with Greg Laughlin of The Five Ages of the Universe, Adams predicts that all this dead matter will eventually collapse into black holes. By the time the universe is 1 trillion trillion trillion trillion trillion trillion years old, the black holes themselves will disintegrate into stray particles, which will bind loosely to form individual "atoms" larger than the size of today's universe. Eventually, even these will decay, leaving a featureless, infinitely large void. And that will be that—unless, of course, whatever inconceivable event that launched the original Big Bang should recur, and the ultimate free lunch is served once more.