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. Learn More