WHAT THE FUCK IS PARTICLE SPIN

[Anonymous No.15998472]

PLEASE IM FUCKING BEGGING YOU TO EXPLAIN THIS SHIT!


What the fuck IS particle spin in physics? People keep saying its like angular momentum but its not, ive been trying to 'get it' for days but nobody will give me a straight explanation.

[Anonymous No.15998473]

>>15998472
Not a homework thread btw im just studying nuclear fusion personally so im trying to learn the basics of Spin is and why atoms with certain spins like to fuse together?

[El Arcón No.15998487]

It's angular momentum that can't be attributed to a classical orbit.

[Anonymous No.15998490]

>>15998472
Electrons behave exactly like spinning charges, but since an electron is a single particle it can't be spinning because only things made of multiple parts can spin, a line can spin (two points), a triangle can spin (three points), a point itself can't spin because there's nothing to spin, if you spin a line the points will swap positions, now if you try and imagine a point spinning what you will actually imagine is a sphere, not a point, because a point can't spin.>>15998473
>and why atoms with certain spins like to fuse together?
I think this has to do with the Pauli exclusion principle, but idk if its the only relevant thing

[Anonymous No.15998491]

Shrink a vector to a point, it's a directed particle aka unit vector. We say it has pin

Take a wedge product of vectors, it's an area spinning in the plane. Shrink it to a point, bam it's a particle with spin.

[Anonymous No.15998509]

>>15998487
>>15998490
>>15998491
You answered my original question very well anons, thank you!

http://large.stanford.edu/courses/2011/ph241/ray1/

Im gonna keep struggling to understand this. Its extremely interesting that spin can double or halve the chance of atomic fusion, but i still dont understand 'why' or what an equation for such a notion looks like..

Thanks again anon's, i think peoples constant relation to 3 dimensional angular relation just confused me by making it seem less quantized then it actually is.

[Anonymous No.15998907]

>>15998473
>learn the basics of spin

[Anonymous No.15998911]

>>15998472
Mathematically, the spin is an angular momentum.
Physically, I think about it like mass in some sense. You can't see mass directly, you can't feel it. You can measure it through indirect means with a scale for example. It's a property of particles like any other that defines how some particle behaves. Like mass defines how an object will behave when forces are applied to it, spin defines how a particle will behave when inside a magnetic field for example.
The particle itself doesn't spin.

[Anonymous No.15998920]

>>15998472
On the one hand it's just a quantum number. Yet another thing that describes a particle. However, it behaves a lot like angular momentum. So it often helps deal with it to treat it as a kind of angular momentum. But only after you understand that it isn't.

[Anonymous No.15998959]

The reason spin exists in the first place is because the fields that particles live in have symmetries and gauge freedoms, which force the allowed wavefunctions to obey certain mathematical laws. Spin-1/2 wavefunctions for example are all based on an irrep of SU(2). If that lost you, don't worry it doesn't make sense to me either.

Here's why spin causes angular momentum.
Relativity says that space and time are on the same footing i.e. if you have some equation that has a derivative in time, it better also have a derivative in space too. Non-relativistically, the momentum operator is proportional to a derivative in space only. Relativistically, this becomes a four-gradient involving both space and time like it should. Angular momentum is just an integral over R cross P where P is the momentum, a.k.a. can be written in terms of the regular (linear) momentum. So then relativistically, angular momentum involves both space and time gradients. That means that the angular momentum that is attributed to spin comes from the evolution of the wavefunction through time.

[Anonymous No.16000332]

>>15998472
electrons spin, simple as. what's there to get?

[Anonymous No.16000525]

>>15998907
Why did araki make him so fuckable

[Anonymous No.16000839]

>>15998472
>People keep saying its like angular momentum but its not
its angular momentum, what is it you dont get?

[Anonymous No.16000841]

>>16000332
>electrons spin, simple as.
its just angular momentum, not an electron doing loop de loop