I am trying to understand how sub-atomic particles like a proton have "spin"?
I have come to understand that this term "spin" is just an analogy for scientists as the proton doesn't literally spin like a ball or a planet. Spin apparently means that it is just the intrinsic property of the particle which makes it behave as tiny magnets even when they are at rest.
So in classical physics, if we take an electrically charged object and spin it, we get a magnetic field. But apparently a proton or electron doesn't need to physically spin to create magnetism, physicists say that this is "intrinsic" in the particle, like it's mass.
But this raises for me several questions and I was hoping that some of our excellent scientific minds here on JWtalk could help me, please.
1) What does it mean that the "spin" or angular momentum is "intrinsic"?
In other words, how does a particle just automatically behave as a magnet even though it is as rest?
I understand the word intrinsic, but I don't understand how a particle just naturally would have magnetism at rest
2) This statement below by this professor of physics just amazed me, I had never heard this before.
So is this professor saying and is he correct that the "spin" of a body like the Earth is made up of the total sum of every single spin of every single elementary particle that exists within the Earth? If so that is mind blowing!
Victor J. Stenger, professor of physics at the University of Hawaii at Manoa, offers another, more technical perspective:
"Spin is the total angular momentum, or intrinsic angular momentum, of a body. The spins of elementary particles are analogous to the spins of macroscopic bodies. In fact, the spin of a planet is the sum of the spins and the orbital angular momenta of all its elementary particles. So are the spins of other composite objects such as atoms, atomic nuclei and protons (which are made of quarks).
So any help, explanations, thoughts that anyone could share on any of this would be great, thanks!