[beefield]

Talking about particle/quantum physics, is there a book/youtube channel/whatnot that would describe (some/main) experiments and results that have convinced physicists that classical physics does not work when you go small. I mean, I know about double slit experiment, but I guess it is a long journey from that to the Standard Model.

So instead of the heavy theory, I'd like to see the stuff that made people scratch their heads in the first place.

[mr_mitm]

The first real head scratchers were the black body spectrum [0] and the fact that atoms are stable.

Rutherford [1] showed that atoms consist of a tiny, positively charged nucleus and rather large negatively charged shell. It was hypothesized that electrons are flying around the nucleus like planets around the sun. But we already knew at that point that moving charges emit radiation, which causes the electron to lose energy and move closer to the nucleus. So it should pretty much immediately collapse into a point. Bohr then showed that if you assume that only certain orbits were allowed, it works out pretty nicely. Nowadays we now that there is such a thing as a ground state, meaning the lowest amount of energy the electron can possibly have around a nucleus is enough to keep it moving.

The idea for quantizing things came from observing the black body spectrum. If you sum up all contributions classically, you get infinity. Planck tried to see what happens if you assume that energy comes in little packets instead of a continuous spectrum. He didn't have any justification for it, but it matched the observations pretty well.

[0] https://en.wikipedia.org/wiki/Black-body_radiation

[1] https://en.wikipedia.org/wiki/Rutherford_model

[simonh]

This is a bit old, but still excellent. https://www.youtube.com/watch?v=XYcw8nV_GTs

This is more up to date and specifically on challenges to the SM. Where is physics going? | Sabine Hossenfelder, Bjørn Ekeberg and Sam Henry https://www.youtube.com/watch?v=b8npmtsfsTU&t=2306s

[MatteoFrigo]

See https://www.feynmanlectures.caltech.edu/I_40.html specifically Sections 40-5 and 40-6, for a discussion of why classical physics fails to explain the specific heat of gases.

As a sibling poster commented, the blackbody spectrum was also inexplicable from a classical point of view (see https://www.feynmanlectures.caltech.edu/I_41.html Section 41-2), but I think that the specific-heat problem was known before the blackbody problem.

[jrpt]

Quantum physics is a separate (but related) branch from particle physics so using the slash "quantum/particle" is mixing up two different things - which one do you really want?

Theoretical Concepts in Physics by Malcolm Longair is a mix of history and physics, by explaining how physicists came to discover their theories. I actually don't think it says much about modern particle physics though. It includes quantum mechanics.

Introduction to Elementary Particles by David Griffiths if you just want particle physics. Griffiths also has an intro book on quantum mechanics.

[beefield]

I'd be interested in all observations that make "non-classical" thinking of physics necessary. I have no deep enough knowledge to distinguish quantum physics and particle physics. So for example what is the experiment that makes us think that particles have something called spin? And what experiment makes us think that the spin can only have distinct values? And so forth.

Anyway, the books you proposed look interesting, thanks.

[Splendor]

Maybe not exactly what you're looking for but these two videos discuss the results of a Fermilab experiment that hints at a crack in the standard model.

https://www.youtube.com/watch?v=kBzn4o4z5Bk

https://www.youtube.com/watch?v=O4Ko7NW2yQo