Hari Sreenivasan:

The term "quantum mechanics" describes the strange doings of the tiniest particles in the universe, where, for example, two objects can occupy the exact same space at the same time, or affect each other even though they're millions of miles apart.

But if that sounds outlandish, hold on to your hat.

Within the realm of quantum mechanics, there is a highly abstract and controversial theory known as "many worlds." It describes the idea that with every decision you make, an entirely new universe springs into existence … containing a new version of yourself!

As bizarre as it sounds, some theoretical physicists believe that "many worlds" is an exact description of reality. Sean Carroll has staked his reputation on it. He's a bestselling author and a professor of physics at the California Institute of Technology.

NewsHour Weekend's Tom Casciato recently visited him at Caltech to discuss his latest book and its implications not just for physics, but for all of us.