47:17You Have Never Actually Seen Light — The Most Disturbing Idea in Physics
A forty seven minute essay built on David Deutsch's book The Fabric of Reality that starts from a single fact, you cannot see light unless it enters your eye, and follows it to the many worlds interpretation of quantum mechanics. It walks through the granular nature of light, the double slit experiment with single photons, Deutsch's shadow photons, and the claim that a quantum computer running Shor's algorithm performs more operations than there are atoms in the visible universe, so the work must be distributed across parallel universes. The final act fuses the block universe with the multiverse to argue that other times are other universes and the flow of time is an illusion. It closes with Hugh Everett and the reason you cannot feel yourself splitting any more than you can feel the earth turn. An honest closing section separates the solid physics from the contested interpretation.