How does film and TV make time travel real? Ellen E Jones and Mark Kermode take a quantum leap into the world of time travel and time loops on screen, from Back To The Future to Groundhog Day.

Mark speaks to theoretical physicist Sean Carroll about how movies like Bill & Ted's Excellent Adventure and Interstellar have handled the science of time travel - and whether it really is just the stuff of fantasy. And he talks to Star Wars: The Last Jedi and Knives Out director Rian Johnson about the dramatic allure of playing with time, and about Rian's 2012 film Looper, which starred Bruce Willis as a criminal sent back to the past to be eliminated by his younger self.

Meanwhile, Ellen explores a sub-genre less concerned with mechanics and physics, and more with emotion and moral dilemmas - the time loop story. She speaks to Black Doves screenwriter Joe Barton about his time loop TV series The Lazarus Project. And film critic Anne Billson runs her through some examples of the genre she finds most - and least - captivating, from Palm Springs to About Time.

Produced by Jane Long