Earth is the only home we've ever known, and it's treated us well so far. But whether it’s climate change, an apocalyptic asteroid, or some horrifying disaster we don’t even know about yet, the Earth won't live forever.
Hard as it is to swallow, cutting-edge theories are suggesting that our universe may not be the only universe. Instead, it may be just one of an infinite number of universes that make up the "multiverse." In this show, Brian Greene takes us on a tour of this brave new theory at the frontier of physics, showing what some of these alternate realities might be like.
In the 1950s and early '60s, a small band of high-altitude pioneers exposed themselves to the extreme forces of the space age long before NASA's acclaimed Mercury 7 would make headlines. Though largely forgotten today, balloonists were the first to venture into the frozen near-vacuum on the edge of our world, exploring the very limits of human physiology and human ingenuity in this lethal realm.
2016 • Astronomy
New discoveries help experts in their search for the first alien moon outside our solar system, which could be Earth-like worlds with the potential for life; they haven't found any, but 21st-century methods might change everything.