Hello there!
I’ve seen a meme saying something like: “Electron spin explained: imagine a ball that’s rotating, except it’s not a ball and it’s not rotating”.
I remember from school the electrons were represented like balls and there was this spin number also.
So, what’s wrong with that? What’s the true from of an Electron?
Sorry for the bad English.
In: Physics
Its not a ball its described by a wave in quantum physics, although we nay never know if thats really the 100% correct form, or if its just a good model for it. According to this it has no shape or volume, so it cant rotate/spin.
It has an intrinsic angular momentum, just like it has intrinsic mass (lets ignore Higgs here) or electric charge, which we call spin or intrinsic spin. But thats just the name because its analogous to if it actually were spinning, but its not.
[Here](https://youtu.be/pYeRS5a3HbE) is a video that actually explains what spin really is, geometrically. Im no expert so i cant be sure, but i thought they did a really good job at least, i thought it was the single best explanation on the internet so far.
An electron is a quantum object. At that level properties like shapes, size, etc. which you know from classical objects don’t really exist anymore (even things like position are difficult to impossible to determine for sure).
Even things like atoms, which are much much bigger than electrons don’t have a clearly defined shape, in the sense that there is a sharp edge between “atom” and “non-atom”.
This is even more true for electrons. Electrons are not just single objects, which can only collide with each other, but they can also show effects like interference, which is a thing that is only possible for waves in classical physics.
That joke is surprisingly accurate.
There is a thing called angular momentum. It’s the thing that makes gyroscopes stay upright. Classically, it’s described by some mass rotating at some distance and speed around an axis. So that’s the rotating ball for you.
Quantum spin is also angular momentum. It has all the same properties… Only associated with elementary particles, which as far as we’re defining them are zero size, or alternatively are the waves that describe them.
But one thing they are NOT is a ball that rotates. School “lied”. That happens a lot, because trying to explain quantum physics to children is like… Explaining quantum physics to children. The information they’re giving you is sufficient for 99% purposes. If you’re interested in the details, you’ll follow up yourself, like you’re doing.
So you end up with a property associated with rotating objects, only no object is rotating. It’s weird, but the quantum world is weird and unintuitive. So properties just exist.
One side note is that there technically is a “thing” “spinning”, but not in the sense we normally understand. In a mathematical sense, where you have a change of an angle around a zero point. It’s called a spinor and it describes quantum spin. But it’s honestly difficult to explain what it does, where it comes from and why that matters. Enough to point out that, again, it’s not the same as a physical object spinning. Despite giving rise to the same property. Just go with it, lol.
Here is a 20-minute Youtube vid about it, that I watched recently.
Physicists were trying to account for all of the energy of an electron and found that they had some energy left over that they couldn’t account for. They found that if they added angular motion to their equations it accounted for the extra energy. So that’s how particles that don’t really have a size or shape came to have a “spin”.
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