{"type":"rich","version":"1.0","provider_name":"Transistor","provider_url":"https://transistor.fm","author_name":"80,000 Hours Podcast","title":"#115 – David Wallace on the many-worlds theory of quantum mechanics and its implications","html":"","width":"100%","height":180,"duration":11387,"description":"Quantum mechanics — our best theory of atoms, molecules, and the subatomic particles that make them up — underpins most of modern physics. But there are varying interpretations of what it means, all of them controversial in their own way. \r\n\r\nFamously, quantum theory predicts that with the right setup, a cat can be made to be alive and dead at the same time. On the face of it, that sounds either meaningless or ridiculous. \r\n\r\nAccording to today’s guest, David Wallace — professor at the University of Pittsburgh and one of the world's leading philosophers of physics — there are three broad ways experts react to this apparent dilemma: \r\n\r\n1. The theory must be wrong, and we need to change our philosophy to fix it. \r\n2. The theory must be wrong, and we need to change our physics to fix it. \r\n3. The theory is OK, and cats really can in some way be alive and dead simultaneously. \r\n\r\n(David and Rob do their best to introduce quantum mechanics in the first 35 minutes of the episode, but it isn't the easiest thing to explain via audio alone. So if you need a refresher before jumping in, we recommend checking out our links to learn more, summary and full transcript.)\r\n\r\nIn 1955, physicist Hugh Everett bit the bullet on Option 3 and proposed Wallace's preferred solution to the puzzle: each time it's faced with a ‘quantum choice,’ the universe 'splits' into different worlds. Anything that has a probability greater than zero (from the perspective of quantum theory) happens in some branch — though more probable things happen in far more branches. \r\n\r\nWhile not a consensus position, the ‘many-worlds’ approach is one of the top three most popular ways to make sense of what's going on, according to surveys of relevant experts. \r\n\r\nSetting aside whether it's correct for a moment, one thing that's not often spelled out is what this approach would concretely imply if it were right. \r\n\r\nIs there a world where Rob (the show's host) can roll a die a million times, and it comes up 6...","thumbnail_url":"https://img.transistorcdn.com/VO1STE7hN95RRg9QdLo4soV2VhhbR9PF5ZZlRhDYcwE/rs:fill:0:0:1/w:400/h:400/q:60/mb:500000/aHR0cHM6Ly9pbWct/dXBsb2FkLXByb2R1/Y3Rpb24udHJhbnNp/c3Rvci5mbS9zaG93/LzQxNDAyLzE2ODM1/NDQ1NDAtYXJ0d29y/ay5qcGc.webp","thumbnail_width":300,"thumbnail_height":300}