A teacher told me that electron don’t even really ‘spin’ the way we understand spin. But somehow they can have angular momentum. And what exactly is the concept of half spin?
In: Physics
Wolfgang Pauli, defined the modern concept of quantum spin called it “classically non-describable two-valuedness”.
Which tells you that there is really no room for a conventional intuition about spin. It just is one of the numbers that defines a quantum particle, like charge or mass and is equally arbitrary.
“Spin” is the term for intrinsic angular momentum of quantum particles. Since the electron is considered a point particle in the Standard Model it cannot really be spinning in a classical sense. We don’t really know more than that about how it arises.
The “units” of spin come from how many turns you need to make to bring the system back to its original state. “Normal” macroscopic objects all return to the same state after 1 full revolution, as do photons and other particles, but for electrons, they actually require 2 full revolutions, so they have 1/2 spin.
Like a lot of quantum mechanics, the math shows these properties, but we don’t know and/or can’t agree on how to interpret the math in terms of stuff that makes intuitive sense to humans.
The “spin” of the electron has about the same relationship to the angular momentum as the “flavour” and “colour” of the quark has to the appropriate macro-world meanings of the word. They are just the convenient terms to describe the quantum properties of the elementary particles.
Imagine you have a toy top that spins around, and you can see it moving in a circle. Now, think about a tiny, tiny marble called an electron. Electrons have something special called “spin,” but it’s not like spinning a top that we can see. Instead, it’s a special way the electron behaves, like a secret trick it can do.
This special trick called spin gives the electron energy and helps it interact with other tiny marbles. Think of it like how magnets stick together or push apart.
Electrons have a special kind of spin called “half spin.” This means they have two special ways they can behave, which we call “spin up” and “spin down.” It’s like having two different moods that the electron can switch between.
So, electron spin is a special trick the tiny marble does, not a spinning motion we can see. This trick gives it energy and two special ways to act.
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