Veritasium
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!✌
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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
Additional References – https://ve42.co/AdditionalReferences-PoLA2
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
Filmed by Derek Muller and Casper Mebius
Produced by Casper Mebius, Derek Muller, Rob Beasley Spence, Gabe Strong, Geeta Thakur, Emilia Gyles, Zoe Heron, Emily Zhang and Tori Brittain
Thumbnail contributions by Ignat Berbeci, Ben Powell, Jakub Misiek, Ren Hurley, and Peter Sheppard
Additional video/photos supplied by Getty Images and Storyblocks
Music from Epidemic Sound
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This shows that we still have no understanding of what is happening. Particles do not explore an infinite number of paths, somehow that exploration would require more energy than the particle is even made of. We need to study what happens as a moving particle encounters chunks of space that it has to dodge (quantum foam?) Resulting in the probabilistic deflection of each particle. This nonsense should be called 'the path catastrophy' and it needs a planck type effort to resolve it.
Does this work the same in a vacuum?
I think there is a basic flaw in the logic at 2:03.
If you definitely want to point you beam of light at point B, then you will have to wave your light beam around until it hits B.
But if you just simply point your light beam anywhere onto the surface of the medium, then the beam of light will bend and go to wherever it wants to go.
Did Vera Hart’s archetype quiz and immediately sent it to two friends. Not because I’m convinced by it yet. I just need to compare everyone’s results now.
Planck was the first 'Mathematiical Physicist'
Who found his equation by fitting the known data curve. Then he searched for its meaning.
This story is the establishment fairy tale and not reality. It's totally backwards bs.
Is “Action” the same as “Quantum Position” or “ String Theory “ ?
I cracked this usa stole is like nikola teslas patterns 😂
So obvious that light unbound by gravity is instant information.
hmm
I think this is the best science video i have ever seen!
2:00 visual is wrong, if a light goes directly perpendicular to a new medium, it will continue directly straight, not bend as displayed
A laser pointer has an output lens that glows with scattered light dimly, also a dust on the lens is shining, this scattered light strikes the diffraction grating film below and can be seen under special angle. If you extend the laser pointer with a tube painted black on the inside, the reflection on the film must mostly disappear. It is a matter of basic linear optics. Even children know that a glowing laser lens is visible from the side.
And talking about trusting equations as such isn't science. Equations are reliable when they make testable predictions in the real world. There you have some very nice equations that describe reality as full of strings, others as a quantized spacetime, and still others as a two-dimensional reality from which another holographic one flows. That's the difference between theories like those of quantum physics or relativity and others that operate in a purely speculative field. Like some of the equations of our friend Feynman, a mathematical genius, without a doubt.
Are we all stupid? The laws that govern quantum mechanics at the subatomic level are not the same as those that govern at larger scales. Why? At the moment, we haven't a clue. That's why we continue to speculate, trying to find the theory of everything that unifies physics. So no, when you get in your car and steer it down a road with your steering wheel to get from one place to another, you don't take infinite paths; you take only one, the one your GPS indicates, for example (if you use one). The same thing happens when you throw a ball, etc., etc., etc. Electrons, photons, and other subatomic particles are different. So the image of the basketball is irrelevant.
A ver si estamos todos tontos
Las leyes que gobiernan la cuántica a nivel subatómico no son las mismas que rigen a escalas mayores
Por qué? de momento ni zorra idea, por eso se sigue especulando tratando de encontrar la teoría del todo que unifique la física.
Así que no. Si te montas en tu automóvil y diriges tu coche por una carretera con tu volante para llegar de un sitio a otro no, no coges infinitos caminos coges uno solo el que te marca tu GPS por ejemplo (si lo usas) lo mismo sucede cuando tiras una pelota etc etc etc.
Los electrones fotones y otras partículas subatómicas es otro percal
Así que la imagen de la pelotita de baloncesto sobra.
this video confirmed a thought of mine, life as a whole, our lives, take every single path too, so there's what I have to say:
"You only live once is a partially false sentence, you will live more than twice, but never the same life twice, you'll certainly keep the same name, same family, but different friends, decisions, everything… But that doesn't mean your current life has to go to waste, don't waste your current life on stupid decisions, because you probably won't read this again. You only live the same life once, it is your choice to make this path the best one, this is still an analysis, but don't take the shortest path neither, speedrunning life shouldn't be done, you already went too far to take the shortest path. Life's only checkpoints is when another version of you reaches point B, when they die."
"You'll live many lives, but only one will be like this one."
So fill your life with as much action as possible, pun intended.
This is one of the craziest things I've ever seen
He doesn't understand the difference between a mathematical abstraction and reality. The paths in the path integral are not "real" any more than the paths in the Hamiltonian action integral are "real". This is woo woo quantum mysticism BS, and I'm surprised to hear it from you. It is literally the same thing as Hamiltonian mechanics, and no one thinks classical particles "traverse every path"…because it's obvious that they don't, we can literally see them.
30:23 since I can see the laser source on the main camera in dark, it is throwing light in all directions (including towards main camera). So my basic logic is saying that you just reflected/ refracted/ sent the red light coming to foil portion to the mobile camera. If it was true laser, I should not be able to see source light in the main camera. Can you put like tube in front of laser source and check if we cannot see the source laser when we put third camera camera at the foil position directly, to ensure no light is coming to the foil portion.
Oops! Verisatium has fallen for the reification fallacy. All paths is not an ontology, but a mathematical technique. Good entertainment though
FIX MOJANG BEDROCK
because bread tastes better than key
my mind blows everytime I watch this video
I thought said this was wrong
It's considerably simpler if you drop the assumption that photons and other quantum particles exist.
Do you need energy to explore all possible pathways
Loved the laser demo… Could genuinely feel his enthusiasm. Beautiful video. Thx. Respects. 🙏
idk about that light experiment… Isn't the light just going in all directions until you found something to reflect it?
I'm just a Luddite, but it seems to me that once we figure out and harness gravity all physics will align.
Here I am, simulating I understand.
Was ein Schwachsinn! Ai halt..
Such interesting concepts, even if I'm going to forget 90% of the information offered, I think the way you're explaining, there's going to be a lot of left over information that I will know because of your videos! Thanks for that!
If the light does all possible parts at once, shouldn't it arrive at different times, since the paths have different lengths?
As a class 11 student from, I am doomed here
Idk… Its seem all a bit trivial to try understanding this any deeper,
Once an object got velocity, it doesn't have infinite directional possibilities… And if an object is stationery, well its just not worth even talking about the theory of a potential trajectories because of course they are infinite…
Action, Lagrangian, path integrals – all good stuff. Useful and powerful.
Least action and path integrals supposedly lead to the dramatic revelation that the quantum (photon, electron, whatever) takes all possible paths.
But path integrals give the same results as the use of wavefunctions. They are equivalent. They are different mathematical methods that give the same result. The wavefunction also _takes_every_possible_path_. So is the path integral the source of any unique revelation?
The word 'possible' has been used somewhat casually. Are there paths that aren't possible? I'd say so. Traversing a path through 2 km of lead is so unlikely as to be basically impossible. Or even 2 cm of black felt. You could leave that path out of the path integral without affecting the result.
The rats nest of paths that is flashed several times in the video appears mostly unphysical. Under what physical conditions would those paths be "possible"? Do we have to include a path that loops around Jupiter (or Uranus) three times? You could but it is not going to affect the results.
I don't find Casper's demonstration convincing at all. There is nothing there that requires least action or quantum mechanics to explain. You could ignore quantum mechanics, consider light to be an EM wave, do the EM wave calculations, and get the same result.
Quantum physics has some figuring out to do, quantum mechanics sometimes proves or disproves that.