11 HN users recommended this talk15 months2012–2025score 17
Years with an HN recommendation, 2007–2026
HN commenters repeatedly recommend it as the talk that finally made quantum mechanics click, especially for programmers.
Ron Garret's Google Tech Talk argues that quantum mechanics is no harder to understand than relativity and that popular accounts wrongly rely on the Copenhagen interpretation. He presents measurement as entanglement and explains phenomena like the quantum eraser.
“This is the video that finally made it click for me[1].” (HN, 2022)
Before you invest three hours to watch these lectures you should know that the title is terribly misleading. These lectures are not about QM at all, they are about the history of QM, albeit told by someone who was actually part of it. But the coolness of hearing the history of QM firsthand is undermined by the fact that Bethe is clearly well past his prime, and he's not particularly good at telling stories. If you want a video that is true to this title I'd recommend this: [link] EDIT: And if you want to really understand QM, there's this: [this video] :-)
This Google Talk [this video] uses entanglement and quantum information theory in a clear and understandable way to explain 'spooky' quantum phenomena, like the quantum eraser, de-coherence, the aspect experiment, and the measurement problem. Even if you don't know any QM, just basic algebra and calculus, it's really approachable. I used to be a fan of the Many Worlds interpretation, but after seeing this, I'm now a big fan of the Quantum Information Theory explanation. Starting about 43 minutes in, he goes into the QM Information Theory explanation, but I'd recommend watching the entire prezo. Link to my original post on the subject: [link]
Clear, approachable explanation of spooky quantum phenomena via entanglement
If I may recommend a lecture given at Google Tech Talks-- "The Quantum Conspiracy: What Popularizers of QM Don't Want You to Know", It really clarified some things for me. [this video]
This is the video that finally made it click for me[1]. Despite the somewhat click-baity title ("What Popularizers of QM Don't Want You to Know") it actually goes into quite a bit of detail of what is and isn't a measurement, in the sense of interactions in a quantum mechanical system that strongly resemble classical behavior (it can be said that the quantum mechanical world is a simulator that can run classical mechanics). [1]: [this video]
Explains what is and isn't a measurement in detail
In fact, the Copenhagen interpretation has been proven wrong by fellow lisper Ron Garret. You can read his paper here: www.flownet.com/ron/QM.pdf and watch his google talk about it [this video] . The problem is, that most people (not scientists, mind you) do not really care anyway, and the Copenhagen interpretation gives you a nice story to tell, which is fairly "strange", yet somewhat understandable. I hate the fact that even science magazines still 100% subscribe to the Copenhagen interpretation, just to attract a greater readership and to be able to use catchier headlines.
Ron Garret's talk arguing against the Copenhagen interpretation
Anyone interested in this can find an excellent lecture here [this video] and of course by looking up leonard susskind's stuff on the black hole wars and universe as a hologram
> (whatever that means) That (implied) question has an answer: measurement is the mutual entanglement of a number of degrees of freedom. See: [link] Or the movie version: [this video]
Measurement as mutual entanglement of degrees of freedom
> Isn't the entire universe one quantum system? Yes. > If so, how can we talk about discrete systems. That is an excellent question! And the answer is that when you do the math, the result of taking a subset of the wave function (the mathematical operation is called a "trace") is something that looks like a classical system. If you want the details, see this paper: [link] Or this video [this video] which covers the same material.
Explains how classical behavior emerges from the wave function
Nothing changes at the time of "wave function collapse". When you measure one particle of an entangled pair, nothing actually happens to the other one. But you don't need to listen to me, check this out: [this video]
Explains why measuring one entangled particle does not affect the other
One explanation[1] i heard is observation is a actually equivalent to entanglement. Now we know that two elements entangled will have to maintain the state corresponding to its entangled peer. Now if you observing (or taking measurement) the whole system gets entangled to the particle. you are observing and hence the wave function collapses. You can look at a better explanation here [1] [this video]
Ron Garrett gave a presentation at Google years ago on Quantum Information Theory that kind of demystified a lot of spooky stuff (like quantum eraser), and I'm wondering how much of this is merely an artifact of the way we're interpreting the math. [this video]
Demystifies spooky quantum effects like the quantum eraser
Personally, I am firmly in the "superdeterminism" camp. To me it's the most elegant interpretation of QM without any mystical measurements magically dependent on "consciousness" and whole universes created on each interaction. If you want to learn basics about it, I recommend watching this video: [this video] Do not mind the (joking) clickbait title, the talk itself is quite good even if you only vaguely remember QM.
There is a very important and often forgotten caveat to the Bell's inequalities: it covers local hidden states. If we are to assume that measurement and particle creation apparatuses are entangled with each other (after all, they had plenty of opportunities since the big bang), then we have a global hidden state and the quantum measurment randomness becomes a simple artifact of removing global state from the picture. This interpretation of QM is usually called "superdeterminism" and, personally, I like it much more than the black vodoo measurement magic with collapsing wave functions or creation of whole new worlds on each tiny measurement. This video can be a good introduction to this topic: [this video] (don't mind the clickbaity title, the video itself is good)
Ages ago I talked about this with Ron Garret here on HN and he pointed me to his Google Talk: [this video] He makes a tremendous case that, yes, we're in a simulation, and the more I learn the more that conviction grows.
Ron Garret's talk making a case for living in a simulation
Mermin put it perhaps most succinctly, that reality is "correlations without correlata", or as Ron Garret coined, the "zero-worlds interpretation"[1] It also makes sense to me on a sociological level, that the way in which this interpretation seems to undermine the very foundation of western, scientific thought is the reason it has been so desperately avoided for so long, with many preferring to believe in an infinite forking (but somehow still "real) multiverse, than the idea that reality itself is intersubjective. [1] [this video]
Quantum erasers are a lot less impressive than they sound. They don't really "erase" anything. You can make a quantum eraser out of a few sheets of polarizing film. See: [this video] around the 15 minute mark for a demo.
I'm working on it (definitely room for improvement there), but the original paper is long and it will probably take me the better part of the day to work through it (and I also have to get some work done). In the meantime, the same conclusion can be reached by a completely different argument: [link] Same content in a video: [this video] UPDATE: Just found this: [link] By way of: [link]
Just about any modern book on QM interpretation will tell you this, though not in so many words. (They won't necessarily endorse this point of view, but they will tell you about it.) Here is my take on it: [link] (Or the movie version: [this video] ) (These are now a wee bit dated, but still defensible.) For something written by an actual physicist I recommend anything by Tim Maudlin (he's a Bohmian, but his pedagogy is without peer) or David Z. Alberts, "Quantum Mechanics and Experience." UPDATE: There's also [link]
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