Print Story So, You Wanna Learn Quantum Mechanics?
By dark nowhere (Sun Oct 17, 2021 at 01:48:54 AM EST) (all tags)
Using the internet for autodidacty can be difficult these days. Search is dead. Clickbait abounds. Instant experts wax burrito¹.

Despite this, with a little help from Algorithmic Providence, I've managed to find heaps of really solid stuff on quantum mechanics. Remarkably, it's very approachable. Even the math.

1. Consider yourself lucky if you don't get the reference.


  • The Biggest Ideas in the Universe by Sean Carroll covers a lot of physics, and each has a Q&A video. It's not teaching material in the sense that you could go and apply this stuff, but you'll learn concepts and see how it all fits together. Highly recommended.
  • The Theoretical Minimum is a collection of courses by Leonard Susskind aimed at getting continued learning students going as quickly as possible, while teaching real physics. These are actual classroom blackboard whiteboard lectures, not that tone-deaf MOOC junk where someone tries to educate a camera.

    The math is taught as-needed. Technically there are some prerequisites, but everything is explained well enough that you can follow along and understand the mathematical meaning of everything that's being taught.

    If you are not interested in doing the classical mechanics course first, you could start on the QM course. Most of the classical stuff that's involved will be mentioned explicitly, so you will know what's going on, it just won't get the full treatment.

    (In case you are binging the stuff, you might want to check Stanford's channel for a playlist for that lecture series. For example: Quantum Mechanics.)

    Finally, there are a couple of books for this series. The site links them in the References section. In a pinch, you can find them on (I debated whether to mention this or not. In the end: do what thou wilt.)

  • NoahExplainsPhysics has a few series explaining physics, including QM concepts. These are structured around the math in a way that makes the math clear and make the connection to the concepts being taught clear as well.

    Due to the way these are presented, they're useful for clearing up any issues about the math. How to do it, how to apply it, what it means — all of that is clear from the examples and explanations he gives.

    The first two are classical mechanics. The Quantum Spin series actually covers quite a lot of QM. Spin is connected to a lot of things, and he goes deep.

    I can't recommend these enough. (If don't want to do a whole playlist, he does have a one-off that I recommend below.)

    Principle of Least Action & Lagrangian Mechanics
    Noether's Theorem Explained
    Quantum Spin


  • Classroom Instructional Vibes
    Physics Videos By Eugene Khutoryansky is a channel I encourage you to use as a reference. Lots of topics in physics explained very well, in an idiosyncratic style you may find familiar.
  • The Metaphysical Space
    David Z. Albert gives a talk on How to Teach Quantum Mechanics. Philosophy professor talks about how to frame QM in a way that makes certain things clear. Not for everyone, but he has an interesting point and makes it well.
  • Uncertainty
    The more general uncertainty principle, beyond quantum by 3Blue1Brown explains that uncertainty (quantum or otherwise) is an everyday thing you can understand given some reasonable assumptions.

    PBS Space Time does a pretty good job on this topic too, in Understanding the Uncertainty Principle with Quantum Fourier Series.

  • Fourier Transform
    But what is the Fourier Transform? A visual introduction by 3Blue1Brown is the best introduction to the Fourier transform I've found. Worth spending some time on, since QM couldn't exist without this, yet it's rarely talked about.
  • Quantum Spin, Symmetry Groups
    In Dirac's belt trick, Topology, and Spin ½ particles, NoahExplainsPhysics demystifies electron spin, and gives probably the best explanation of symmetry groups you will ever get.
  • Quantum Information (The Holographic Principle, AdS/CFT)
    In Quantum information and spacetime (part 2), John Preskill explains quantum information. In particular, this has a great explanation of the holographic principle.

    While this is relevant to quantum computing, it applies more generally and teaches about concepts that are used in other contexts. Especially recommended if you are going to learn about string theory.

Quantum Computing

  • Patrick Hayden explains the basics of quantum computation in The Quantum Computational Universe (part 2. No prior knowledge is assumed.
  • Quantum Computational Supremacy explained by Scott Aaronson. He talks about what Google's demonstration did and how to interpret it.
  • John Preskill's Ph/CS 219A Quantum Computation class. I had high hopes for this because Preskill is really good. But there are problems.

    First, this wasn't recorded because Preskill is good at lecturing this way, it was recorded out of necessity because world events turned his class into a remote learning class. He's alone, talking to a camera, teaching from slides and occasionally having computer problems.

    Second, this is a bit abrupt. You'll need to understand the math and he won't be explaining very much of it. Noah's series can help with this, but you might still be missing a few things.

    However, it is a good course. Probably the best on the subject. If you're looking to learn this in detail, this is the course for it and it's freely available online.

    Ph219/CS219 site
    Ph219/CS219 lecture notes


This stuff is lighter than the rest. The vast majority of things in this category would be excluded outright, but these have enough merit that I couldn't rightly leave them out.

  • Sabine Hossenfelder tends to talk about things nobody else does. She's also known for being outspoken about her criticisms of programs and ideas in physics and science in general, but she's not controversial for the sake of it.
  • PBS Space Time covers many topics, sometimes with surprising depth for this kind of channel. This could almost have been listed as reference material, but the videos tend to bring up more than they explain.

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So, You Wanna Learn Quantum Mechanics? | 4 comments (4 topical, 0 hidden)
Sean Carrol by ucblockhead (4.00 / 1) #1 Sun Oct 17, 2021 at 02:20:49 PM EST
I agree, that series was outstanding.   I feel like it really gave me a deep grounding in how modern physics works the way no other popular science works have.

I also have really enjoyed Hossenfelder's channel.
[ucblockhead is] useless and subhuman

He explains the structure of the theory. by dark nowhere (2.00 / 0) #2 Sun Oct 17, 2021 at 05:31:03 PM EST
That's usually left out by others. Even the classroom stuff doesn't always piece it together very well.

I wish he better explained the stuff about violating energy conservation, or left it out. I suspect he was being very naughty when he said it.

I wish Sabine had a course. In English. She's so clear about things, even when she's being opinionated.

See you, space cowboy.

[ Parent ]
Fourier uncertainty by wumpus (2.00 / 0) #3 Mon Oct 18, 2021 at 10:46:24 AM EST
explains Heisenburg's uncertainty very well, although bluebluebrown uncharacteristically wimps out on it. I think the real way to see uncertainty in Fourier theory mostly comes in to play when looking at "windowing" in digital signal processing theory.

The other issue is that it doesn't really explain superposition and how measuring/defining subatomic material (even light) forces it to change in ways that weren't directly measured. But it is a great place to start: once you realize that if matter has a frequency, then it has certain properties of waves, and uncertainty is part of the package.


I wouldn't say uncharacteristic by dark nowhere (2.00 / 0) #4 Mon Oct 18, 2021 at 06:25:36 PM EST
I find a lot of the time 3b1b doesn't quite get me there. I usually only realize it in hindsight.

I think of what he said about it as the cause of (or maybe a concise version of) the situation with windowing (also IIR vs FIR, which is the connection I made. Morally the same thing.) It would have been nice for him to call this out so people would realize DSP has a lot to say about QM.

Quantum superposition is not really in scope here. I don't think anyone has quite covered superposition as well as I'd like. Maybe one day I'll be up to the task and give it a go.

Sabine has a 5 minute explanation of superposition and entanglement that does a good job of clarifying that whole situation. She's more clear-minded on the subject than Sean Carroll is.

See you, space cowboy.

[ Parent ]
So, You Wanna Learn Quantum Mechanics? | 4 comments (4 topical, 0 hidden)