What exactly does it mean for an object to have “intrinsic” angular momentum? How can angular momentum be intrinsic instead of dependent on the frame of reference?
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Spin as a quantum property (aka intrinsic angular momentum) can be thought of as analogous to angular momentum in the macro world, but it’s not even close to a decent analogy. There is nothing actually spinning in an elementary particle like there is in a rotating macroscopic object. Electrons, quarks, photons, etc. all have “spin” and the math really makes it seem like there’s something moving in a way that we would see as spinning around an axis if it were scaled up to a large object. But there’s nothing actually spinning or rotating in any way. Truth is, other than the math working so well, we have no idea what the property we call “spin” actually is. What we do know is that the cumulative effect of lots and lots of electrons in an iron object (for example) spinning when exposed to a magnetic field can make the iron object spin on a macro level to preserve angular momentum. So, bizarrely, even though nothing spins in an electron, put enough of them together and influence their quantum spin with a magnetic field, you can make a macro-sized object actually spin. Quantum mechanics is weird. No matter how strange you think it is, it’s actually far stranger.
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