Is it possible to go backwards through time? We travel forwards every day, but traveling back could let us change our past, visit old friends, or manipulate the timeline to our benefit... Although our knowledge of space and time remains incomplete, we can still use what we know to consider possible time machines. But what kind of paradoxes would this entail and how can we resolve them? Join us today on a special journey through time. An educational video written and presented by Professor David Kipping This video is based on research conducted at the Cool Worlds Lab at Columbia University, New York. You can now support our research program directly here: https://www.coolworldslab.com/support All music used is licensed by SoundStripe.com or through Creative Commons: ► "It's Always Darkest Before the Dawn" by Hill, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7441 ► "Waking Up" by Atlas, licensed through SoundStripe.com: https://app.soundstripe.com/songs/3984 ► Cylinder Four (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► "Always Dreaming" by Caleb Etheridge, licensed through SoundStripe.com: https://app.soundstripe.com/songs/5534 ► Cylinder Two (http://chriszabriskie.com/cylinders/) by Chris Zabriskie (http://chriszabriskie.com/); licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/) ► "Fable" by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/6312 ► "Selha" by Stephen Keech, licensed through SoundStripe.com: https://app.soundstripe.com/songs/7102 Further reading and resources: ► Echeverria, F., Klinkhammer, G. & Thorne, K. S. (1991), "Billiard balls in wormhole spacetimes with closed timelike curves: Classical theory", Phys. Rev. D., 44, 1077: https://ui.adsabs.harvard.edu/abs/1991PhRvD..44.1077E/abstract ► S. Kalyana Rama & Siddhartha Sen (1994), "Inconsistent Physics in the Presence of Time Machines": https://arxiv.org/abs/gr-qc/9410031v1 ► Stephen Hawking (1992), "Chronology protection conjecture", Phys. Rev. D., 46, 603: https://ui.adsabs.harvard.edu/abs/1992PhRvD..46..603H/abstract ► Max Tegmark (1997), “On the dimensionality of space time”, CQG, 14, L69: https://arxiv.org/abs/gr-qc/9702052 Films clips used: ► The Assassination of Jesse James by the Coward Robert Ford (2007) Warner Bros ► Interstellar (2014) Paramount ► The Grey (2011) Open Road Films ► About Time (2013) Universal Pictures ► The Time Machine (2002) Dreamsworks Pictures ► Passengers (2016) Columbia Pictures ► Back to the Future (1985) Universal Pictures ► Avengers: Endgame (2018) Walt Disney Studios Motion Pictures ► Somewhere in Time (1980) Universal Pictures ► Lucy (2014) Universal Pictures ► The Matrix (1999) Warner Bros ► Immortal Beloved (1994) Columbia Pictures ► Prisoners (2013) Warner Bros ► X-Men: Days of Future Past (2014) 20th Century Fox ► Captain America: Civil War (2016) Walt Disney Studios Motion Pictures ► Inception (2010) Warner Bros ► Silver Linings Playbook (2012) The Weinstein Company ► The Dark Knight Rises (2012) Warner Bros ► Hidden Figures (2016) 20th Century Fox Television clips used: ► The Expanse (Legendary Television) ► Star Trek: The Next Generation (Paramount) ► Dr Who (BBC) ► Star Trek: Enterprise (Paramount) ► Game of Thrones (HBO) ► Genius (National Geographic) Other video clips used: ► ESO spacetime diagram https://www.spacetelescope.org/videos/heic1812b/ ► Earth orbit animation by Brad Freese: https://www.youtube.com/watch?v=R2lP146KA5A ► Hefele Kating experiment video by Gideon Boulton: https://www.youtube.com/watch?v=LW4NsxCglp4 ► SpaceX satellite launch: https://www.youtube.com/watch?v=K_NFCeNrryg ► Wormhole animation by Robert Wilde: https://www.youtube.com/watch?v=Fb4fpfPWL7k ::Playlists For Channel:: Latest Cool Worlds Videos ► http://bit.ly/NewCoolWorlds Cool Worlds Long Form Videos ► http://bit.ly/CoolWorldsEssays Cool Worlds Research ► http://bit.ly/CoolWorldsResearch Guest Videos ► http://bit.ly/CoolWorldsGuests Q&A Videos ► http://bit.ly/CoolWorldsQA Tabby's Star ► http://bit.ly/TabbysStar Science of TV/Film ► http://bit.ly/ScienceMovies ::Follow us:: SUBSCRIBE to the channel http://bit.ly/CoolWorldsSubscribe Cool Worlds Lab http://coolworlds.astro.columbia.edu/ Twitter https://twitter.com/david_kipping THANKS FOR WATCHING!! #TimeTravel #TimeMachine #CoolWorlds