If you're having a hard time visualizing the Big Bang, let Columbia University astronomy and physics professor Janna Levin show you how it all started. In this first-rate animation that shows the Big Bang more concisely than I've ever seen, the professor makes an important point about the origin of our doughnut-shaped universe: Before the Big Bang, there was no space or time. There was nothing. That huge explosion didn't happen in space — it happened in the middle of nothing.
Perhaps the most intriguing theory in this video by animation studio Thornberg & Foresters is that maybe our current universe is just a "bounce" from previous universes that expanded and contracted, going back to infinity and beyond. Or maybe we're living inside just one of trillions of other universes. Whatever really happened, we know one thing: It's full of stars.