Comment by fasterik
11 hours ago
So many entry-level explanations of quantum mechanics start with classical physics, waves, particles, the double-slit experiment, etc. and then jump straight to infinite-dimensional Hilbert spaces. In my opinion, there's way too much conceptual baggage that comes with these concepts [0].
As a non-physicist, QM only clicked for me when I learned the linear algebra of one- and two-qubit systems and observables on those systems [1]. The math is accessible at a pre-calculus level, and the most "counter-intuitive" aspects of QM (interference, the uncertainty principle, entanglement) make perfect sense in this framework. I think it's the best starting point for understanding what QM really says.
[0] That's not to say they aren't important historically or for a complete understanding of QM. I'm talking about conceptual understanding for someone, especially an amateur, encountering QM for the first time.
[1] Chapter 2 of Nielsen and Chuang is what did it for me. It's heavygoing if you've never seen linear algebra before, but I don't know of a clearer explanation of the postulates of quantum mechanics.
The math is one thing, but I find the idea that the fundamental pieces of reality aren’t particles a little unsettling.
The classic double-slit experiment is kinda bizarre when one considers the “single electron” case.
https://profmcruz.wordpress.com/wp-content/uploads/2017/08/q...
Do you have any recommended resources that you used to help learn the linear algebra?
Start with 3Blue1Brown's "Essence of Linear Algebra" series https://www.youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2x...
Axler's "Linear Algebra Done Right" https://linear.axler.net/LADR4e.pdf
Nielsen and Chuang's "Quantum Computation and Information" Chapter 2. (Available online, but legality depends on where you live)
If you're interested primarily in QM rather than linear algebra, I'd recommend not working through all of Axler, but instead using Nielsen and Chuang to learn about qubits and observables, and using Axler to fill in the gaps.
"A Course in Modern Mathematical Physics: Groups, Hilbert Space and Differential Geometry" by Peter Szekeres has several chapters on linear algebra early on, starting with sets and groups and including tensors (which you absolutely need for QM).
I loved it.
https://linear.axler.net/
not sure about its specific applications to quantum mechanics, but I worked through MIT OpenCourseWare's Linear Algebra class (taught by Gilbert Strang) and I thought it was amazing. The lectures are very very good.
It makes sense in the framework but the framework makes no sense. The model contradicts regular intuition.
If we've learned anything from modern physics, it's that our regular intuitions are often wrong. The framework makes perfect sense mathematically, and it makes the right predictions experimentally. It's still controversial how exactly the framework relates to reality, which is where you get into interpretations of quantum mechanics.
One of my favourite examples of this pedagogically is how kinetic energy is quadratic with velocity. It's easy to tie into things people think they understand, like braking distance. Our intuitions are wrong even in shockingly simple problems.
1 reply →
Nature gives jack crap about our intuition
Agreed.
Quantum Processes, Systems, & Information by Benjamin Schumacher and Michael Westmoreland is another good treatment along those lines.
Mike and Ike is almost always my standard recommendation.