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Is the spin of an electron based on its direction of angular momentum? Is it based on the right hand rule of angular momentum? Does Spin up means that the electron is spinning anti-clockwise and spin down means that the electron is spinning clockwise according to the right hand rule?

OR

What do we mean when we say spin up of a particle or spin down of a particle?

Bhavesh
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    Have a look at What is spin as it relates to subatomic particles? and its linked questions. Nothing is actually spinning. Electrons are not little billard balls. – ACuriousMind Mar 25 '16 at 16:52
  • Are you saying electrons do not spin or are you saying you think they don't spin? Many things in nature from raindrops to galaxies spin and spin is related to magnetic moment. Has it been proven that electrons do not spend? Thanks – Bill Alsept Mar 25 '16 at 18:58
  • Especially this answer of the question ACuriousMind linked stated that spin has really to do with rotation. More see here. – HolgerFiedler Mar 25 '16 at 21:08
  • @BillAlsept: though ACuriousMind would probably consider this a misleading description, an electron is an excitation in a quantum field not a little ball like some microscopic version of a pool ball. It has an angular momentum, but this cannot be simply interpreted as something spinning in the way a macroscopic object spins. – John Rennie Mar 26 '16 at 06:53
  • @John Rennie: Thanks, I don't actually picture an electron as a solid ball either. But angular momentum relates to the quantity of rotation of a body. Why use words like rotation, spin and angular momentum if there is none? More importantly why is it more true to say that electrons don't have spin as opposed to saying that they do have spin? What's the proof? Thanks – Bill Alsept Mar 26 '16 at 07:20
  • @BillAlsept: physicists are human too (contrary to the rumours). Firstly they tend to use terms they're familiar with and secondly terms are often coined before the physics is fully unerstood. The current terminology is largely an accident of history and we're stuck with it. Since physicists understand what words mean in the physics context we just get on with it. The terminology does tend to exclude the layman and that's unfortunate, but the situation isn't going to change any time soon. – John Rennie Mar 26 '16 at 07:24
  • So back to my original question. Has it been proven that electrons do not rotate or have spin? Why is it more true to say that they do not rotate? Thanks – Bill Alsept Mar 26 '16 at 07:44
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    Yes, it has been established that electrons do not just rotate; there are allowed values for spin that are not allowed for regular angular momentum (in more mathematical terms, I think it can be described ilke this:fundamental particles with spin are associated with irreducible representations of the spin group which is locally the same as the rotation group and therefore not so simple to distinguish from it---hence the "rotational terminology"---but possesses certain irreducible representations that the rotation group does not possess. The two things are thus fundamentally different). – Danu Mar 26 '16 at 17:52
  • You said do not JUST rotate? So forget the word spin. Has it been proven that electrons cannot rotate? – Bill Alsept Mar 26 '16 at 18:30
  • @BillAlsept I don't know if they rotate or not, but my question is that what is the meaning of spin up and spin down. – Bhavesh Mar 26 '16 at 21:09
  • @Bhavesh: I hear you but we are being told that electrons cannot turn, rotate or physically spin so how does the right-hand rule work then? I just wanted confirmation that it has been proven that electrons cannot turn. – Bill Alsept Mar 26 '16 at 21:18
  • @BillAlsept as far as the standard model of particle physics goes, electrons do not rotate (they're point particles anyways: How'd you like to rotate them?) When, in my earlier comment, I said "do not just rotate", I meant "do not simply rotate". – Danu Mar 27 '16 at 14:06
  • @Danu the best scientist in the world considered the Ptolemaic system proven until it wasn't. I am only asking why is it more true to say electrons do not rotate than considering that maybe they can. So their called point particles, does that mean we can't ask questions about what they may look like? That's like the opposite of infinity and just as unaccountable. Is there proof or not that electrons cannot rotate? – Bill Alsept Mar 27 '16 at 17:31

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