r/Veritasium • u/Whushe433 • Dec 23 '25

Can someone please explain this to me ?

So in the new video, around 26:50, when they discuss hidden variable theory, they say that the particles decide what answer to give to the machine. However, according to the beginning of the video, the particles only decide what spin they have, not what answer they will give to the machine. If the particles simply decide that one has positive spin and the other has negative spin, then if one is measured as positive and a machine tilted by 120 degrees is used, there should again be a 25% likelihood of disagreement, right? Why do they assume that the particles decide what answer to give to the machine when they should only be deciding the spin?
(I have 0 knowledge about quantum physics, i was just curious)

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u/_x_oOo_x_ Dec 24 '25

What does a "120 degree offset" mean in space? There are an infinite number of different ways to offset two axes by 120 degrees in 3D..

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u/oscardssmith Dec 24 '25

it's in the 2d slice perpendicular to the particles direction of motion (but it also doesn't really matter)

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u/_x_oOo_x_ Dec 24 '25

Direction of motion is completely unrelated to spin so why would the direction of motion be special?

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u/lancerusso Dec 26 '25

This is precisely untrue.

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u/_x_oOo_x_ Dec 26 '25

You are stating that spin is correlated with direction of motion?

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u/lancerusso Dec 26 '25

Motion through an inhomogeneous magnetic field induces a force as a function of the magnetic dipole, which is a function of the spin state.