How is this physically possible?

Question

Anyone who knows alot about physics, please help me.
I understamd the idea of 'spin' but how can a particle have a spin of 1/2? I do not understand how this works. If you know, please tell me. Also, I know what Pauli's exclusion principle is, but how does it work and why does it happen?
Thanks in advance for your help.

Answer 1

Just about any quantum mechanics text will treat angular momentum and show you the standard notation.

The 's' as in s=1/2 is not the spin angular momentum. It's just a label (a quantum number) that distinguishes different types of particles. The magnitude of the spin angular momentum depends upon s, as does the number of possible spatial orientations of the angular momentum vector.

By the way, if you really understand spin you're ahead of me! I still don't get it!

As far as the Pauli exclusion principle goes, I think it's a consequence of a wavefunction having to be equal to its 'flipped' self (I forget the details now) -- and for an antisymmetric wavefunction the only way it can work is if the wavefunction is zero ... man, I'm rusty on this -- you'd (I mean both of us) had better look it up...

Answer 2

According to the quantum mechanics , the angular momentum of any system is quantized.
The magnitude of angular momentum S can only take on the values accordind to this relation :
S = h square root s ( s+1)
Electrons are called spin 1/2 because their intrinsic angular momentum has s = 1/2

Answer 3

That's because 'spin' isn't exactly the right word, but it's the closest simple word we have for something like angular momentum. When a particle physicist uses the word, he means something different from the ice skater kind of spin.

There really isn't a simple, clear, accurate explanation of quantum physics. As far as I know, there's not a human alive for whom it makes intuitive sense. But it has tremendous predictive value, so we use it.