Electron spin vs proton spin

1. Oct 29, 2013

anorred

I'm no physicist, so please enlighten me. Is an electron's spin related to the spin of a proton? Do they spin at the same frequency? I read that electrons have a higher magnetic moment and stuff.

2. Oct 29, 2013

Simon Bridge

There is no special relationship between the electron and proton spins... though the concept of spin applies to both of them.

It is not useful to think of electrons and protons as being little balls that physically spin about on an axis though...

3. Oct 29, 2013

neptunedude

Why do electrons and protons spin?

4. Oct 29, 2013

sophiecentaur

That's not a valid "why" question - and many of the questions that people ask are not. (Listen to Feynman ranting about "why" and you will see what I mean; a google search will soon throw up a link). All that can be said is that it helps to explain what happens if you assign them spin.

The reason that particles are said to have spin is that, when they interact with systems, the principle of Conservation of Angular Momentum has to apply (as always). If you want to account for the results of experiments, the angular momentum of your experiment seems to change. This cannot happen so you need to account for it by saying that some angular momentum 'goes into' the electron (or whatever). So giving them angular momentum explains what happens when they interact.
It is not helpful (as stated earlier) to think of little objects spinning in space because such mechanical models will take you down the wrong road.

5. Oct 29, 2013

ZapperZ

Staff Emeritus
This is also the wrong concept based on the way you asked.

Electrons and protons DO NOT SPIN.

They do, however, have a property called "spin quantum number". There's nothing spinning here. The name 'spin' stuck due to historical reasons. Do not be fooled by the name. Rather, try to understand the physics.

Zz.

6. Oct 29, 2013

sophiecentaur

Absolutely. Likewise with Strangeness, Colour, Flavour and all the other loopy terms that those (brilliant but nerdy) West Coast academics introduced in an attempt at humour and smartness. These words are all used well out of their normal, colloquial context. Beware!!!

7. Oct 29, 2013

Simon Bridge

8. Mar 18, 2016

Eric Eliason

Thank you sophiecentaur. I was 2.5 months into a book. Since orbital shapes mimic possible planetary orbits I assumed atoms could be this way. I didn't realize that the difference between a Bohr and Schroedinger model was an angular momentum that had calculations match with the latter more than the former. Now I don't have to spend 1.5-5.5 months more on a wasted book. You saved someone time and I hope to spend it on something better.

9. Mar 19, 2016

Eric Eliason

I found out that the Schroedinger equation includes angular momentum too. My book still may work!

10. Mar 19, 2016

Simon Bridge

Yes - the Schrodinger equation is, in general: $$\left( \frac{\hbar^2}{2m}\nabla^2 - V(\vec r) - i\hbar \frac{\partial}{\partial t}\right)\Psi(\vec r, t) = 0$$ ... the potential $V(\vec r)$ should describe whatever it is that influences the behaviour of what you are interested in. If the angular momentum is important, then it should have an angular momentum term in it.