Could time travel ever be science fact? Time itself may be something you can bend and stretch. Trying to understand if time travel can be possible teach us a lot about the universe. It forces us to take on some of the toughest unanswered questions in all of physics and will ultimately probably lead to deeper understanding of the very nature of the cosmos.

Time travel is not forbidden by the laws of nature, but to build a time machine, we would need to understand more about those laws and how to subvert them than we do now. And every day, science does learn more. In this film Horizon meets the scientists working on the cutting edge of discovery - men and women who may discover how to build wormholes, manipulate entangled photons or build fully functioning time crystals. In short, these scientists may enable an engineer of the future to do what we have so far been only able to imagine - to build a machine that allows us travel back and forward in time at the touch of a button. It could be you! Science fiction? Watch this film.

Blowing your mind, that's what Doctor Who's all about. What makes it all so fun is that while all this crazy science fiction is going on, there's actual facts. You've got space travel, you've got time travel, you've got regeneration. These are all the powerful themes of Doctor Who. And they're also the things that drive science forward.

Ideas about time and space are explored in the changes that constellations undergo over time, the redshift and blue shift measured in interstellar objects, time dilation in Albert Einstein's theory of relativity, the designs of both Leonardo da Vinci and spacecraft that could travel near light speed, time travel and its hypothetical effects on human history, the origins of the Solar System, the history of life, and the immensity of space. In Cosmos Update, the idea of faster-than-light travel by wormholes (researched by Kip Thorne and shown in Sagan’s novel Contact) is discussed.

For thousands of years, mankind has found comfort in its presence. It's been a lantern for nighttime travellers, a timekeeper for farmers and a location finder for sailors at sea. For some cultures, it's even been a god. It's the only cosmic body ever visited by human beings. From afar, the Moon's luminance has captivated us since the beginning of time. And a closer look at the beacon in the dark sky reveals an ever-present source of myth, intrigue, controversy and unsolved mysteries. The field of science may cast an empirical light on some things about the Universe, but lunar experts are the first to admit they don't have all the answers when it comes to our Moon. This episode explores the theories behind Lunar Transient Phenomena that have left scientists stumped for centuries; takes to the Canadian waters to see how the Moon effects our planet through tides; and dusts off some age-old myths and weighs arguments that without our Moon, humanity may not even exist.

Explore the myths, misconceptions, truths & amazing mysteries of our unique universe. Could life exist on Mars? Is time travel possible & does Einstein's theory of relativity support it?