logoalt Hacker News

fasterik • yesterday at 10:30 PM • 6 replies • view on HN

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.


Replies

BobbyTables2 • today at 3:55 AM

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.

mattm • yesterday at 11:12 PM

Do you have any recommended resources that you used to help learn the linear algebra?

➕ show 4 replies
podocarp • yesterday at 11:21 PM

It makes sense in the framework but the framework makes no sense. The model contradicts regular intuition.

➕ show 2 replies
anotherpaulg • today at 3:20 AM

Agreed.

Quantum Processes, Systems, & Information by Benjamin Schumacher and Michael Westmoreland is another good treatment along those lines.

wnoise • today at 1:41 AM

Mike and Ike is almost always my standard recommendation.