Comments by "Lepi Doptera" (@lepidoptera9337) on "Professor Dave Explains" channel.

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  197. There are no particles. Quanta are small amounts of energy. When we detect one we get a "click" in a detector. The "clicks", i.e. when and where these detectors absorb a small amount of energy seem random. We therefor start to collect statistical information (histograms) about them. In the limit of large numbers these histograms become probability distributions. The theory predicts these probability distributions as the product between a wave function, its conjugate complex and a Hermitian projection operator that represents the absorption spectrum of a physical measurement system (the detector). What happens is that almost nobody who makes these videos actually knows WHY the formalism looks the way it looks. For that you would have to read Heisenberg's matrix mechanics papers, where this is somewhat laid out in a language that still relates to physics and that will give you a bit of physics intuition about what is happening. A few years later a mathematician called von Neuman generalized the relatively straight forward physics and math in Heisenberg's papers to an abstract mathematical formalism that comes from functional analysis (the mathematics of linear operators and function spaces). At that point the connection to measured quanta of energy disappears from the textbooks and is replaced with a general notion of "quantum mechanical state". You also lose a sense that this "state" means the state of a quantum mechanical ensemble, i.e. an infinite repetition of the same experiment. Instead it starts looking like as if the wave function relates to an individual system. That is complete nonsense. It was never constructed that way, neither by Heisenberg nor by von Neumann. It's just easy to loose sight of the translation between physical measurements ("clicks") and mathematical formulas.
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  330. @jeffafa3096 The problem with physics on the internet is not restricted to Sabine. Most YouTubers either oversimplify the actual facts to the point where they present a completely false mental model (this is especially the case for everything related to quantum mechanics) or they are completely uneducated about the subject matter to begin with and they basically just regurgitate hearsay in a game of telephone. Either way you are not getting useful information. This, by the way, is not even restricted to the internet. I would make the same statement about most layman books (Hawking in particular wrote some horrible mental models into his layman books that the physics world is still trying to exorcise from the public's memory... with little success.) I only know a few domains well enough to talk about them. Physics is one, electrical engineering (at the circuit board level) another. I do not talk about chemistry, biology and ice fishing in any level of detail. I simply don't know enough about them. What I can tell you is that Sabine often enough misrepresents physics badly enough to disqualify her from being a good source. Of course some of what she says is correct, but the context in which she puts those snippets is designed to garner attention and to increase her view count. So where do you find "the truth"? In the physics library and the laboratory... in form of a full time 24/7/365 physics career. I hate to break it to you, but physics is no different from playing the piano. Either you can play the piano or you can't. No pianist in the world can tell you how one plays a Chopin piano concerto in Royal Albert Hall. Either you do or you don't. There is no trying and there definitely is no "peeking in".
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