Can You Actually Go Back in Time? (Real Physics)

You come home in a time machine after 1 year, and your little sister is now 19. Today we build a time machine from scratch, with one rule: only physics that has been tested in a lab, on a plane or in space. Two fast-forward buttons, one idea for rewind, and a party nobody came to. Tell me in the comments: 1 year for you, 7 years at home. Would you go? Chapters 0:00 Pihu's door 0:57 Let's build a time machine 1:43 Button 1: Speed 2:42 1971: the clocks that took a flight 3:13 Time travel in your phone 3:43 Astronauts: the biggest time travellers 4:31 99% of the speed of light 4:53 Why didn't Pihu's time slow down? 5:10 Why not press the button all the way? 5:56 Button 2: Gravity 6:54 Was Interstellar real? 8:09 Rewind: the wormhole 8:59 A wormhole time machine in 3 steps 10:04 Negative energy 10:54 The grandfather paradox 11:24 Hawking's party 12:25 The final account 12:48 Back at Pihu's door 13:24 One question for you Sources: Hafele & Keating, Science (1972) · NIST optical clocks, 33 cm (2010) · Morris, Thorne & Yurtsever, PRL (1988) · Lamoreaux, Casimir force (1997) · Hawking, chronology protection (1992) Photo credits: Stephen Hawking in zero gravity: Jim Campbell / Aero-News Network, CC BY 3.0 (Wikimedia Commons) · HP 5061A caesium clock: Binarysequence / Wikimedia Commons, CC BY-SA 3.0 · Einstein at the Bern patent office: Lucien Chavan, public domain · Shubhanshu Shukla aboard the ISS: NASA, public domain Footage: Earth from the ISS, NASA (public domain) Music and sound effects: Epidemic Sound (Finding Melody, DOX Pt. II, Trace, Orbit, Helix Nebula, Mistaken Identity, Longing for Home) #timetravel #physics #science