What’s so weird about Quantum Mechanics

I think I can safely say that nobody understands quantum mechanics.”
(R. Feynman)

Richard Feynman, probably smoking because he was trying to cope with quantum mechanics.

Quantum Mechanics (QM) is the “best” theory of the world physicists have at the moment (at least of everything apart from gravity). But it’s infamously hard to wrap one’s head around what it actually means. It’s probably the first time in physics where it becomes really apparent that the mathematical language in which we describe a theory can work, while it at the same being close to impossible to give an intuitive interpretation of the mathematical structure. Feynman's words tend to be used as a free pass for physicists to act like thinking about interpretations of QM is a waste of time, because it’s impossible to understand it either way.

This is the first article of a two-part series: I realized it’s too hard to cram all that material into just one text, and I am mindful of the stress one can experience when learning about QM (story of my undergraduate studies…).

So in this article, I will focus on the measurement procedure in QM and what that tells us about the general setup of the fundamental objects that constitute reality, so-called quantum systems. The second article will use this as a foundation to elaborate on the problems encountered when trying to interpret quantum mechanics.

First of all: Why is it so…