They are the biggest questions that science can possibly ask: where did everything in our universe come from? How did it all begin? For nearly a hundred years, we thought we had the answer: a big bang some 14 billion years ago.

But now some scientists believe that was not really the beginning. Our universe may have had a life before this violent moment of creation.

Horizon takes the ultimate trip into the unknown to explore a dizzying world of cosmic bounces, rips and multiple universes, and finds out what happened before the big bang.