Something Strange Happens When You Trust Quantum Mechanics

2025-03-05

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Does light take all possible paths at the same time? 🌏 Get exclusive NordVPN deal here ➵ https://NordVPN.com/veritasium It’s risk free with Nord’s 30 day money-back guarantee!✌

A massive thank you to Dr. Andrew Mitchell for all his help and expertise. If you want to delve further into this topic then we highly recommend his lecture on Classical physics derived from quantum mechanics: https://www.youtube.com/watch?v=2iuLwWDYC4U&t=1s

We’re incredibly grateful to Prof. David Kaiser, Prof. Steven Strogatz, Prof. Geraint F. Lewis, Elba Alonso-Monsalve, Prof. Christopher S. Baird, Prof. Anthony Bloch, and Prof. Stephen Bartlett for their invaluable contributions to this video.

A special thanks to Mahesh Shenoy from FloatHeadPhysics for his help with this video. Check out his excellent intuitive video on the UV Catastrophe here (Sep 2024): https://www.youtube.com/watch?v=ALEDjjAVZSY

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0:00 What path does light travel?

2:40 Black Body Radiation

6:47 How did Planck solve the ultraviolet catastrophe?

9:42 The Quantum of Action

13:25 De Broglie’s Hypothesis

15:16 The Double Slit Experiment

20:00 How Feynman Did Quantum Mechanics

25:01 Proof That Light Takes Every Path

31:16 The Theory of Everything

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Sign up to our Patreon to watch the Q&A for free: https://www.patreon.com/c/veritasium

Try Snatoms! A molecular modelling kit I invented where the atoms snap together.

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References:

Armin Hermann (Nov 1974). The Genesis of Quantum Theory (1899-1913). - https://ve42.co/genquanttheor

Richard P. Feynman (1985). QED The Strange Theory of Light and Matter. - https://ve42.co/qed

A fantastic book on the history of the Principle of Least Action: Rojo, A. and Bloch, A. The

Principle of Least Action: History and Physics. - https://ve42.co/Bloch2018

Coopersmith, J. (2017). The lazy universe: an introduction to the principle of least action. Oxford University Press. - https://ve42.co/LazyU

PBS Space Time. (Nov 2021) - https://www.youtube.com/watch?v=Q_CQDSlmboA

Sabine Hossenfelder. (May 2022) - https://www.youtube.com/watch?v=A0da8TEeaeE

Max Planck (1901). On the Law of Distribution of Energy in the Normal Spectrum. Annalen der Physik - https://ve42.co/lawdistenergy

Paul Ehrenfest (1911). Welche Züge der Lichtquantenhypothese spielen in der Theorie der Wärmestrahlung eine wesentliche Rolle?. Wiley Online Library - https://ve42.co/quantthermrad

Nils-Erik Bomark and Reidun Renstrøm (Aug 2023). The Ultraviolet myth. Proceedings of Science - https://ve42.co/uvmyth

Planck's law. In Wikipedia - https://ve42.co/planckslaw

PBS Space Time. (Jul 2017). - https://www.youtube.com/watch?v=vSFRN-ymfgE&t=10s

Einstein and The Photoelectric Effect. (Jan 2005) via APS News - https://ve42.co/einsteinphotoelec

Louis de Broglie (1924). On the Theory of Quanta. - https://ve42.co/theoryquanta

Larry Sorensen (2012). Path Integrals 1. University of Washington - https://ve42.co/pathintegrals

Feynman’s Method of “A Particle Exploring All Possible Paths”. (Mar 2018) via Pure Dhamma - https://ve42.co/allposspaths

A great intuitive video on the Feynman path integral approach - https://www.youtube.com/watch?v=Sp5SvdDh2u8&t=1253s

Origins of Quantum Theory. via University of Pittsburgh - https://ve42.co/origquanttheor

Images & Video:

Nobistor Altona 1880 via NDR - https://ve42.co/streetlight

Edison incandescent lights by William J. Hammer via Wikimedia Commons - https://ve42.co/edinclights

The full expanded form of the Standard Model Lagrangian by Chen Ning Yang et al. via Wikipedia - https://ve42.co/stmodellang

Muon Ray. (2011). https://www.youtube.com/watch?v=-QUj2ZRUa7c

Muon Ray. (2011). https://www.youtube.com/watch?v=1C7abO7LtV0

Bohrs Atomic Model via EEEGUIDE.COM - https://ve42.co/bohrmodel

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Directed by Casper Mebius

Written by Casper Mebius and Derek Muller

Edited by Trenton Oliver and Peter Nelson

Animated by Fabio Albertelli, Mike Radjabov, Ivy Tello, Andrew Neet and Emma Wright

Illustrations by Jakub Misiek, Tommy A. Steven and Cainejan Esperanza

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