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.

Zachary Quinto charts a journey to determine whether time travel is possible. He meets a man who claims to have traveled back in time due to a secret government program and a group of people living in Liverpool known as 'time slippers'.
Zachary makes a visit to the CERN headquarters in Geneva, where he attempts to understand the origins of the universe and the dimension of time. Equipped with this new knowledge, Zachary tests his own perception of time with an elaborate skydiving experiment to see if he can slow down time itself.

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.

What if we could travel not just through space, but through time itself? If you could travel through time, would you change the past or the future? What if you found it couldn’t be changed? What price does the time traveller -- and the people they are closest to -- pay? This is a journey from H. G. Wells' The Time Machine through ideas like The Grandfather Paradox and The Butterfly Effect to the professional time traveller that is the ever popular Doctor Who. Steven Moffat, David Tennant, Karen Gillan, and Neil Gaiman offer a unique perspective on the Doctor. Edward James Olmos reveals the hidden meaning of the language he created for the vision of the future that is Blade Runner. Bob Gale and Christopher Lloyd take us behind the scenes of Back to the Future, while Ed Solomon describes the joy of solving a time travel conundrum for Bill & Ted’s Excellent Adventure. But what would be the physical and emotional cost to the time traveller? Audrey Niffenegger explains what inspired her novel The Time Traveller’s Wife. And what if someone from the future tried to travel back in time to warn us? Would we believe them? From the apocalyptic tones of 12 Monkeys to the drama of Quantum Leap and the comedy of Groundhog Day, time travel is a subject that has been irresistible to the creators of every type of science fiction.

Is Time Travel Possible? Stephen Hawking explores the world's favourite scientific 'what if?' He explores all the possibilities, warping the very fabric of time and space as he goes. From killing your grandfather to riding a black hole, we learn the pitfalls and the prospects for a technology that could quite literally, change everything.

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.