Stephen Hawking considers whether time travel is possible; ideas include DeLoreans, atomic clocks, a giant black hole and a large swath of New York.

The world's most famous living scientist sets a team of ordinary people the task of demonstrating the physical truth of our universe.

Why Are We Here?: The world's most famous living scientist sets a team of ordinary people the task of demonstrating the physical truth of our universe.

Stephen Hawking leads three people on a journey of discovery featuring racing cars, ice skaters, balloons and running tracks.

Self-assembling machines, light-up bacteria and a physical demonstration of evolution revolutionise volunteers' views of life.

Stephen Hawking takes a group of three volunteers on make a journey of discovery. They encounter a number of challenges to help answer some major questions about the world around us.