Is This What Quantum Mechanics Looks Like?

Silicone oil droplets provide a physical realization of pilot wave theories.

Huge thanks to:
Dr. Daniel Harris
Prof. Stephen Bartlett
Filmed by Raquel Nuno

Thanks to Patreon supporters:
Nathan Hansen, Bryan Baker, Donal Botkin, Tony Fadell, Saeed Alghamdi

The standard theory of quantum mechanics leaves a bit to be desired. As Richard Feynman put it, "I think I can safely say that no one understands quantum mechanics." This is because observations of experiments have led us to a theory that contradicts common sense. The wave function contains all the information that is knowable about a particle, yet it can only be used to calculate probabilities of where a particle will likely turn up. It can't give us an actual account of where the particle went or where it will be at some later time.

Some have suggested that this theory is incomplete. Maybe something is going on beneath the radar of standard quantum theory and somehow producing the appearance of randomness and uncertainty without actually being random or uncertain. Theories of this sort are called hidden variable theories because they propose entities that aren't observable. One such theory is pilot wave theory, first proposed by de Broglie, but later developed by Bohm. The idea here is that a particle oscillates, creating a wave. It then interacts with the wave and this complex interaction determines its motion.

Experiments using silicone oil droplets on a vibrating bath provide a remarkable physical realization of pilot wave theories. They give us a physical picture of what the quantum world might look like if this is what's going on - and this theory is still deterministic. The particle is never in two places at once and there is no randomness.

Edited by Robert Dahlem

Sound design by A Shell in the Pit

[johnredberg]

Dude, I have a PhD in quantum information theory, and I've never heard of these droplets. This analogy is absolutely beautiful. Even when it breaks down for other quantum numbers such as spin, it's the most elegant visualization I've ever seen to help you wrap your mind around the early problems of quantum mechanics. This should be shown at schools everywhere (with the proper disclaimer that there aren't always classical explanations for quantum phenomena). Loved your presentation!

[veritasium]

Common complaint: Bell's theorem rules out hidden variable theories.
Response: No, it rules out *local* hidden variable theories - hidden variable theories are fine if they involve faster-than-light interactions.
John Bell himself was a fan of pilot wave theories as this 1986 quote demonstrates "While the founding fathers agonized over the question 'particle' or 'wave', de Broglie in 1925 proposed the obvious answer 'particle' and 'wave'. Is it not clear from the smallness of the scintillation on the screen that we have to do with a particle? And is it not clear, from the diffraction and interference patterns, that the motion of the particle is directed by a wave? De Broglie showed in detail how the motion of a particle, passing through just one of two holes in screen, could be influenced by waves propagating through both holes. And so influenced that the particle does not go where the waves cancel out, but is attracted to where they cooperate. This idea seems to me so natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that it was so generally ignored."

[tonywillingham]

The double slit has been haunting me since I first saw it in chemistry class 35 years ago. It blew my mind how something was both a wave and a particle. I can now sleep at night.

[Szczawik]

I feel like a caveman introduced to electricity in a way that i understand.

[sammydemorris]

*I like how he went straight into the topic, instead of having an intro* 👌

[MasterDeanarius]

I feel most comfortable with a superposition of both the Copenhagen interpretation and the pilot wave interpretation at the same time.

[maximilianbeyer]

I can‘t even describe how much i liked that demonstration. We were doing the double slit experiment years ago at school, it recently popped up in my head again and haunted me since then. Especially how a single photon can interact with itself. This demonstration makes so much sense and gives me a greater understanding of what could be going on, it‘s just amazing.

[stalthyone]

As always Derek, thanks for making something that’s intrinsically complicated seem so elementary, I wish all teachers shared the same passion you have for STEM!

[AVNewsCast]

Is it crazy that pilot wave dynamics gives me an inner peace and the Copenhagen interpretation fills me with a mild anxiety?

[sethreynolds]

This short video helped me understand quantum mechanics better than any 2 hour lecture I’ve seen 😂

[bobbybs]

WOW, I bow my hat to you. I believe you have just delivered the most intuitive and understandable introduction to quantum mechanics

[jeffj]

My god! I finally get Quantum mechanics, @3:20, I saw a man who is bald and not bald at the same time!

[enhydralutra]

I don't think I have a preference for which interpretation that I like, but I understand the pilot wave interpretation almost instantly when coupled with the visual learning tool of silicone oil. For the first time, the double slit experiment doesn't baffle me.

[cygnus_zealandia]

This reminds me of work by David Bohm which I first came across a few decades ago in his book "Wholeness and the Implicate Order". There are a number of videos now about this interpretation of Quantum Mechanics such as : David Bohm's Pilot Wave Interpretation of Quantum Mechanics. Your video of macroscopic behaviour of oil drops in a an analogous way really helps illustrate this. Thank you for making this subject more widely known.

[sreezonpanchbibi]

5:56 this is the first time I've seen darek stutter. It's not bad to see him being a human once in a while lol. Loved the vid!

[Robin_Nixon]

For me this is Derek's most eye-opening video to date - totally thought-provoking!

[adarshtiwari]

no background music.
nothing to dictate your emotions towards the video.
just a video which gives information concisely and effectively.
AWESOME!

[Ncaa]

It’s interesting how similar the droplet travel is compared to the Alcubierre warp drive. Maybe instead of warping space and time we could isolate it and position ourselves out of the center of the isolation wave to get momentum in a specific direction?

[adamcombs]

This was exceptional. I've been watching and reading everything that crosses my path for 20 years and never seen something that made it all click quite like this unless it was gospel. I think u r on to something absolutely beautiful

[nicholasgalluzzi]

It's one thing to study a subject and be able to imagine these concepts but having it explained so conceptually and linearly is a certainly appreciated and well thought out way of education. Good job mate I love it.