I read Feynman lectures on physics Volume 1 Chapter 37 for the 2nd time. It has the best explanation of the 2-slits experiment for me. 1 of the factors behind my <3 for physics is how amazing the universe is. The wave-particle duality is so amazing. I like that Feynman wrote that there was no established idea deeper than quantum mechanics. There's still no established idea; quantum mechanics is a pillar of physics. I like that he talked a bit re hidden variables. I just wanna add that a hidden-variable idea must be nonlocal.

Chapters 1–36 aren't prerequisites for Chapter 37. You can read 37 at once.

Free online course on the mathematical formalism of quantum mechanics for quantum computing researchers and engineers with limited mathematical background.