Answering Questions About Time Travel, Aliens & Negative Gravity

What happens to gravity when matter converts to energy? Neil deGrasse Tyson and co-host Paul Mecurio dive into fan questions about the speed of light, time machine mistakes, and what Neil would do if he were an alien. Could a time machine land you in empty space because the solar system wasn’t “there” yet? If Neil were an alien meeting a human for the first time, what would he ask about? Will there one day be more black holes in the universe than stars? And how exactly does gravity behave when energy is released during fusion? Do we understand the speed of light? We discuss how precise our measurement of the speed of light is. We get into how negative gravity would make a wormhole. We explore how your eyes might see color differently if you evolved under a blue star, why visible light is only a sliver of the electromagnetic spectrum, and how the cosmic microwave background acts as a kind of universal clock. Why do metal boats float? Neil explains buoyancy and why heavy things can still float. When matter is lost to energy during fusion, what happens to the gravity? Is our solar system made of many supernovae? Plus, what is on the other side of the speed of light? Thanks to our Patrons daniel gordon, Amadeusz Synowski, Geo Bucur, Alexander Dent, Kimberly, Jordan, Kieran McMillen, Nico, Nicholas Stegers, Cuyler Cochran, Nicholas Alonso, William, Melissa Harper, Harrison White, DRaymond831, Jeff Imparato, Pascal Sanders, Fabiola Horváth, Ryan McNamara, Damian Spencer, Lucas Hoopingarner, Matt, Greg Juhl, mary beth frohnapfel, Sam Green, Btyan758, Nicole Pernat, MilesHigh, Simon Cooke, Laszlo 🌍🚀🪐, Andy Demsky, Adam Arnold, Sergio Silva, Lewis Lobdell, Mortakapo, Thomas Celia, ali kansso, Kenneth Mcfarland, JJ Sullivan, Ivan Gonzalez, Jerry, Dennis Boston, Earnest Stephens, Adriano Boriani, CAlvin Wait, Jeff, sandra newell, Will, Pam, and Ed Einowski for supporting us this week. Timestamps: 00:00 - Introduction: Grab Bag 01:56 - Time Machines Are Also Space Machines 06:53 - If You Were an Alien, What Would You Ask Humans? 12:30 - Will There Be More Black Holes Than Stars One Day? 16:31 - The Cosmological Constant 21:37 - Wormholes & Gravity 27:22 - What If We Orbited a Blue Star? 32:06 - Is the Cosmic Microwave Background a Universal Clock? 34:19 - Opposite of the Speed of Light 39:14 - Bouyancy 42:31 - What Happens to Gravity in Mass-Energy Conversion? 44:38 - How Many Supernovae Are We Made of? 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