I am trying to understand the measurement of spin, in order to understand Bell's paper on the Einstein-Podolsky-Rosen paradox.(adsbygoogle = window.adsbygoogle || []).push({});

When we measure the spin of a fermion in the direction of unit vector, will the result be:a

1. a value of either +0.5 or -0.5, and upon measurement, the fermion adopts an eigenstate of the spin operator in which the spin is aligned witha

or

2. a value of 0.5 cos θ, where θ is the angle betweenand the direction of spin the particle has adopted as a result of the measurement, and θ may be anywhere in [0, π)a

or is it something else?

Thank you for any help.

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# What happens when we measure spin of a fermion?

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