zlacker

>>qqqqqu+(OP)
Quantum spin. Electrons aren't really spinning, right? But why do we call it spin? I know it has something to do with angular momentum. What are the possible values? Is it a magnitude or a vector? Is there a reason we call it "spin" instead of "taste" or some other arbitrary name? How do you change it? What happens to it when particles interact?

>>pjungw+uk
> Electrons aren't really spinning, right?

Correct.

> But why do we call it spin?

Because it is a physical quantity whose units are those of angular momentum, and we have to call it something.

> What are the possible values?

+/- h/4pi where h is Planck's constant. (It is usually written has h-bar/2 where h-bar is h/2pi.)

> Is it a magnitude or a vector?

It's a vector that always points in a direction corresponding to the orientation of the apparatus you use to measure it.

> Is there a reason we call it "spin" instead of "taste" or some other arbitrary name?

Yes. See above.

> How do you change it?

You can change an electron spin by measuring it along a different axis than the last time you measured it. The result you get will be one of two possible values. You can't control which one you get.

> What happens to it when particles interact?

Their spins become entangled.

>>lisper+Zn
> It's a vector

It's not exactly a vector...

>>madhad+dN
It only has direction + magnitude right? (±h/4π)e_i for some unit vector e_i.

So it can be written as a vector? No?