# What does it mean when an electron is said to have a “spin”?

264 views

Is it literally like the electron is rotating super fast, or something more complicated?

In: Physics

As far as I can understand from the simple english wikipedia article: electrons do have some momentum that somehow resembles spinning, but not exactly as it would be in normal physics. Also, the electron spin refers to some magnetic properties and the orientation of the electron.

If someone understands this better than me, please correct me!

The electron is not actually spinning, but some magnetic properties of the electron are what you would expect if it were spinning.

Electrons don’t spin. We observe that a beam of electrons is split in two by a magnetic field so they have some kind of magnetic moment. It’s a kind of angular moment. We can even look at how energy levels work out in our calculations and comparing it to experimental results we find that some quantity is missing and if we introduce spin it fits perfectly.

If we were to calculate the spin as rotation for the electron using classical electron radius we’d get a way faster velocity than the speed of light so its not angular momentum in the classical sense and even mathematically the quantity doesn’t transform as you’d expect it to with classical intuitions in mind.

Spin is a quality that a particle has because it’s that particle. It’s linked to magnetic effects like circular currents and also comes from the QM equivalent to rotations but it’s not literally spinning like a little ball since an electron isn’t a little ball.

Spin is a property that things have. Kind of like “electric charge.” If you have something, such as an electron, it has this property that helps describe how it behaves. Two different electrons with a different value for their ‘spin’ behave in different ways (ish).

*Mathematically* this abstract property behaves kind of like spinning. Things either ‘spin’ one way or the other way, and their ‘spin’ can have different magnitudes. If you stick two things together their ‘spins’ “combine” in a similar way to how physical spinning works. So we call this property ‘spin.’ We could call it other things instead; we could call it “feeling” or anything we want to.

It isn’t actually spinning. With fundamental particles (such as – probably – electrons) they have no size, no dimension, so they physically cannot spin. They just have this property that acts, mathematically, like spinning. Except when we get into quantum mechanics the distinction between “actually is” and “acts mathematically like” becomes a bit blurry, so some things we would expect to see from spinning particles (like magnetic interactions) we see from ‘spin’.