Main Question or Discussion Point
I've been reading my physics book about Maxwell's equations. It makes sense to me that an electric and magnetic wave could be self supportive and vary with time. What doesn't make sense to me is why it should travel through space, in other words vary in space. The derivation of the wave equation from Maxwell's equations is very suggestive if not proof. I just want to know how you could know where the wave begins and what starts it. And if non varying electric and magnetic fields start it and are present far away instantaneously, why don't the electromagnetic waves start far away as well. The book I'm reading only explains it by saying that the magnetic and electric fields start the waves nearby and don't give a reason why they should think that. Do all changes in values of electric or magnetic fields have to propagate out at the speed of light or do places far away change instantaneously. Maybe I should differentiate between electric fields caused by changing magnetic fields from electric fields caused by charges but electrodynamic books don't seem to differentiate.