Saturday, 8 August 2015

I don't understand magnetism!

I'm having trouble understanding magnetic monopoles. Magnetic forces we know about are the result of electric charges in motion. As a result, the idea of there always being two magnetic poles makes sense, because the motion of charges has a direction and the magnetic poles are perpendicular to that direction. Consider something simple like a spinning sphere with electric charges on it. If you look at the sphere one way the spin will be clockwise and you will see one magnetic pole (I forget which!). If you look at another direction and you see the spin anti-clockwise you will see the opposite magnetic pole. Having a magnetic monopole is like trying to cut a spin in half, so that you can see a clockwise spin of charge but no anti-clockwise spin. It makes no geometric sense. There are situations where what look like monopoles appear but these are in reality the result of things that are very thin and stretched so that you can only see the effects of the opposite spins at long distances - it's just looking at the ends of a system with both North and South poles.

So, I'm wondering if magnetism makes sense at all as anything fundamental. It's simply electrostatic charges + movement, and so 'magnetic field lines' are badly named, and everything can be re-formulated in terms of electrodynamics.

What am I missing?