From World Science Festival.
Does quantum mechanics actually imply that every possible outcome of every decision happens somewhere in an expansive reality? And if so, what does that mean for probability, free will, and our understanding of the universe itself?
Brian Greene sits down with David Deutsch, widely regarded as the father of quantum computing, to examine what many physicists are still reluctant to accept about their own theory. They explore why the many-worlds interpretation isn’t just a philosophical curiosity, what the wave function is really telling us about reality, and how decision theory may rescue probability in a fully deterministic multiverse. Deutsch also introduces constructor theory, his framework for rethinking the foundations of physics entirely and explains why the questions we’ve been trained not to ask might be the most important ones in all of science.
This program is part of the Rethinking Reality series, supported by the John Templeton Foundation.
Participant: David Deutsch
Moderator: Brian Greene
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00:00 Rethinking Reality: What’s Actually Real?
02:50 From Classical to Quantum: When Things Stop Making Sense
05:30 What’s Wrong with Probability in Physics?
08:10 Determinism vs Randomness (What’s Really True?)
10:40 The Multiverse Explained (Many Worlds Theory)
13:20 Do Multiple Versions of You Really Exist?
16:00 Probability Without Chance
18:40 When Decision Theory Meets Quantum Physics
21:30 How Do You Make Choices in a Quantum World?
24:30 Betting on Reality (How Decisions Actually Work)
27:30 Is Probability Even Real?
33:30 Thought Experiments That Break Your Intuition
36:30 Common Misunderstandings About the Multiverse
39:30 The “Quantum Suicide” Idea (And Why It’s Dangerous)
49:17 Probability as a Tool, Not Something Real
51:30 Responding to Critics (Albert & Wallace)
54:30 What Does It Mean to Be Rational?
57:05 The Mistake People Make About “Versions” of Themselves
01:01:00 Free Will vs Physics: Do We Really Choose?
01:04:30 Why It Feels Like We Have Control
01:12:00 Different Levels of Reality (And Why They Matter)
01:14:00 Constructor Theory Explained
01:22:20 Final Thoughts: Adapting to a Stranger Universe
What Is Quantum Mechanics Really Telling Us? | World Science Festival
https://www.youtube.com/channel/UCShHFwKyhcDo3g7hr4f1R8A
