What would a four-dimensional being see if it looked at us? In this episode, Neil deGrasse Tyson and Chuck Nice answer fan questions covering higher-dimensional surgery, space elevators, alien intelligence, and colliding galaxies. Could spacetime itself be a cosmic crystal? Could 2D creatures exist, and if so, how would we even know? If 4D beings turned sideways, would we disappear like cartoon characters? We wonder whether we could make 4D surgeons do our operations for us. Could the Trantor Starbridge from Foundation actually work? Neil explains the physics behind a space elevator, how it would reach geostationary orbit, and why the dream faded once rockets got efficient. Chuck wants to know what kind of music you’d play during the world’s longest elevator ride. If a superintelligent alien could answer any one question, what would you ask? Neil wonders if the human brain is smart enough to understand the entire universe, or are we just too dumb? Can learning happen without human connection? Neil argues that even an AI tutor can’t replace the ever-changing human condition. What makes spacetime flat? Can there ever be a “universal now”? We ask whether you’d need absolute coordinates to return somewhere, factoring in the expansion of the universe. Finally, we explore the cosmic heavyweights: supermassive black holes. Could they swallow entire galaxies? What happens when two galaxiesand their black holes collide? Neil explains why the universe is mostly empty space, how black holes grow through mergers, and whether spacetime itself might behave like a supersonic lattice or even a cosmic crystal. Thanks to our Patrons Joei Brianne, Robert Simons, Isiah Campbell, DEVVON WILMOT, mark horgan, Jesse Carruth, John Aktiv, Kgaleberkeley, Jordan Crist, Alex Gonzalez, Guy, Jack Molyneaux, Mike, CJ Brooks, Thomas Jones, Ashley, Matt H, Pamela Carroll, Kristie Nixon, Wolter Wielenga, Richard Breytenbach, Will Mansell-Brown, Wayne Eyjolfson, Ashlanne, Jeff, PatternsComplexity, Venessa, Maya Hawthorne, Lil.Mazikeen, David Stokes, Samantha, vijay raghunathan, Jon Kerr, Micheal Charles, Alicia Reed, Petrovici Bogdan, Jordan Fofonoff, Yawaridi Southerland, Rodney Ross, Ted Doyle, Alish, Yelson Rodriguez, dahonetwo ., Janis Purens, Oscar Blanco, Roy Frank Sproule III, Tayla Szabadics, Jens Frederik Lennert Olsen, Gabe, Daniel, Nora, masterbuilderej, Brad, Will, James H English, Evolved Finch, Kioshana LaCount Burrell, Lynda Osborne, Micheal Tiberg, Damein Alexander, Jared Craig, wqf3qwf32tgf23qg, Zane Smith, Ondřej Dubina, Chimenem Wodi, George Stewart, Robbie & Annie James, John Koehler, Megan, David Bayles, robenheimer, Kiryl Medina, paul paulson, Justin Reinschmidt, Tammye, Henry C Weismann IV, and Eric Schwartz for supporting us this week. Timestamps: 00:00 - Introduction: Grab Bag 01:23 - Do 2D Beings Exist? 06:21 - Could We Make a Space Elevator? 11:36 - Neil’s Question For an Advanced Alien 17:10 - Is Human Connection Essential for Learning? 19:23 - Why is Spacetime Flat? 21:16 - Is There a Universal Now? 23:32 - Pitfalls of Time Travel 28:45 - Does Light Ever Do Work? 35:00 - Will Our Black Hole Swallow the Galaxy? 39:29 - When Galaxies Collide 41:22 - Could Spacetime Be A Crystal? Check out our second channel, @StarTalkPlus Get the NEW StarTalk book, 'To Infinity and Beyond: A Journey of Cosmic Discovery' on Amazon: https://amzn.to/3PL0NFn Support us on Patreon: https://www.patreon.com/startalkradio FOLLOW or SUBSCRIBE to StarTalk: Twitter: http://twitter.com/startalkradio Facebook: https://www.facebook.com/StarTalk Instagram: https://www.instagram.com/startalk About StarTalk: Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up! #StarTalk #NeildeGrasseTyson