I have a simple question. I hope I don\'t get a stupid answer. Where does the ma

Question

I have a simple question. I hope I don't get a stupid answer. Where does the magnetic field of a permanent magnet comes from AND why is it permanent (are we dealing with perpetual motion)?

This is what wiki is saying: "The spin of the electrons in atoms is the main source of ferromagnetism, although there is also a contribution from the orbital angular momentum of the electron about the nucleus. When these tiny magnetic dipoles are aligned in the same direction, their individual magnetic fields add together to create a measurable macroscopic field."

What the wiki is saying is correct, but we have to think further or go one step further... So put your head out of the box:

THIS IS NOT THE ANSWER I WANT TO HEAR. Because then I can ask why is the electron spinning (or what is the origin of spin) and that for an infinit time (CRAZY)? This is of course a physics question......We are missing an important energy source, unless you know where this form of energy is coming from and why it is permanent.

Explanation / Answer

The electron is spinning for an infinite time. Yup, it's crazy. Quantum theory does allow for persistent currents, not just electron spin.

In fact you can see this sort of quantum perpetual motion in action at everyday scales with superconductivity and superfluidity. A current flowing in a loop of superconducting wire persists indefinitely without a power source.

This is perpetual motion of what Wikipedia calls the "third kind", elimination of dissipative forces. It cannot be used as an energy source or to reduce entropy (first and second kind). So we are not "missing an important energy source" in that sense.

[Added:] I'll build on amr's comment to a different answer, which makes a relevant observation: you can say the same thing about the electron orbiting the nucleus. Its orbit should decay via electromagnetic radiation and it should spiral into the nucleus. But this is not what happens! Atoms are stable!

This is one of the very facts that lead to quantum theory in the first place. This isn't the place to give an introductory course to quantum theory (and I am not the person to do it), but it was proposed that some things can change only in discrete steps (quanta), not continuously, and the electron's angular momentum is one of them. And this proposal explains many many things that non-quantum explanations don't.

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