Andrew Strominger is a theoretical physicist at Harvard. Please support this podcast by checking out our sponsors: - Eight Sleep: https://www.eightsleep.com/lex to get special savings - Rocket Money: https://rocketmoney.com/lex - Indeed: https://indeed.com/lex to get $75 credit - ExpressVPN: https://expressvpn.com/lexpod to get 3 months free EPISODE LINKS: Andrew's website: https://www.physics.harvard.edu/people/facpages/strominger Andrew's papers: Soft Hair on Black Holes: https://arxiv.org/abs/1601.00921 Photon Rings Around Warped Black Holes: https://arxiv.org/abs/2211.01674 PODCAST INFO: Podcast website: https://lexfridman.com/podcast Apple Podcasts: https://apple.co/2lwqZIr Spotify: https://spoti.fi/2nEwCF8 RSS: https://lexfridman.com/feed/podcast/ YouTube Full Episodes: https://youtube.com/lexfridman YouTube Clips: https://youtube.com/lexclips SUPPORT & CONNECT: - Check out the sponsors above, it's the best way to support this podcast - Support on Patreon: https://www.patreon.com/lexfridman - Twitter: https://twitter.com/lexfridman - Instagram: https://www.instagram.com/lexfridman - LinkedIn: https://www.linkedin.com/in/lexfridman - Facebook: https://www.facebook.com/lexfridman - Medium: https://medium.com/@lexfridman OUTLINE: Here's the timestamps for the episode. On some podcast players you should be able to click the timestamp to jump to that time. (00:00) - Introduction (06:34) - Black holes (11:37) - Albert Einstein (31:05) - Quantum gravity (35:17) - String theory (46:05) - Holographic principle (54:02) - De Sitter space (59:14) - Speed of light (1:06:02) - Black hole information paradox (1:13:41) - Soft particles (1:22:48) - Physics vs mathematics (1:31:58) - Theory of everything (1:47:20) - Time (1:49:45) - Photon rings (2:05:26) - Thought experiments (2:13:47) - Aliens (2:19:25) - Nuclear weapons
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The speed of light as a speed limit and the concept of black holes defined theoretically as a region of space-time from which light cannot escape were established by Einstein, who later on wrote a paper stating that black holes did not exist, based on his field equation which was later solved by Schwarzschild.
The theory of gravity has never been proven exact and corrections need to be made for both Maxwell's equations and Newton's laws of gravity depending on the scale of measurement.
The clash between quantum mechanics and general relativity is an area of great excitement and potential for new discoveries in physics, as it suggests that there must be a more complete theory that incorporates both. This theory should involve modifications to Einstein's theory of gravity and account for quantum effects that deeply modify the equations.
While we don't know if string theory describes the physical world, it is a consistent reconciliation of quantum mechanics and general relativity. While it hasn't been ruled out as a unified theory of nature, it's unlikely that we would be able to experimentally prove it in the foreseeable future.
Brian Greene discusses the current understanding and limitations of string theory, including its ability to solve the infinities problem and Hawking's puzzle about black holes, but also its current inability to describe a big object like a black hole.
The three simplest space-times are flat space-time, negatively-curved space-time, and positively-curved space-time, and we can have curvature in a way that mixes up space and time. The holographic principle is not yet understood for either flat space or asymptotically, the Sitter space, which we appear to be living in as the universe continues to expand.
The theory that a black hole can store information on a holographic plate, sitting on the surface of the black hole, has been mathematically and intuitively understood with detailed explanations by string theorists.
The concept of zero energy particles is a mystery and ignoring them may lead to the conclusion that angular momentum is not conserved. These particles are known as soft particles and have zero energy which is proportional to their wavelength.
The world of theoretical physics, specifically string theory, may seem devoid from a connection to the physical world, but the promise of experimental validation and the belief in the unity of mathematics and physics drive continued exploration.
This episode explores the limits of physics, particularly in relation to the potential inability to explain certain phenomena such as the human psyche despite advancements in string theory and other scientific frameworks.
The hosts discuss the status of the physical laws that we have, and whether it is possible to have a theory of the origin of the universe that can predict everything about our universe, from black holes to star systems.
The idea of space being emergent means that time is just along for the ride. There is no definitive answer yet on whether time is fundamental or emergent.
Theoretical physicist Michio Kaku marvels at the concept of black holes as mirrors, absorbing photons that are sent their way. He describes why he finds them the most interesting things in the universe, particularly due to the mystery they represent to theoretical physics.
The quantum system that describes a black hole may correspond to a region of space-time that includes the photon ring, according to a paper proposing that a warped black hole's photon ring is part of the black hole hologram. The research offers evidence in lower-dimensional examples to support the idea that the holographic plate of a black hole sits beyond the horizon and that the quantum system inside the horizon should include the photon ring.
Theoretical physicist Brian Greene discusses the possibility of finding alien life and how this could potentially be one of the biggest discoveries for the 21st century.
The discussion compares the possibility of artificial intelligence outsmarting humans to the invention of nuclear weapons, mentioning that it was inevitable regardless of the brilliant people who helped make it happen.
The responsibility of a scientist working on AI development goes beyond just figuring out what's possible. They have a podium to influence society and a duty to make a positive impact as citizens of the planet. As the universe is much stranger than we can think, it's crucial to be responsible and make the world a better place.