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Oh, here's a cool thing. although I can't draw it.
Newton's 3rd law is a law of reciprocity. I push on an object, the object pushes back. It's also in a sense a formulation of Mometum Conservation.
Going into EM theory, one can set up a thought experiment where you have two electrons traveling perpendicular to each other. They produce radial electric fields, which obey Newton's 3rd law. However, since they are moving charges, they also generate magnetic fields. The force on electron A due to the mag. field of electron B is _NOT_ equal and opposite to the force on electron B due to the mag. field of electron A. Newton's third law is violated. uh oh.
Since Newton's third Law is pretty much a verson of Momentum Conservation, this situation breaks Momentum Conservation. This is bad. So how do we resolve this? Well, some genius comes up with the idea that the missing momentum is in the Field! Thus, we now see where this idea that light has momemtum comes from. The field itself can carry energy and momentum. This was an odd concept at the time. the Idea of a field was pretty much a mathematical abstraction to allow for "action at a distance" and there wasn't any "physical" significance.
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And if you say to me tomorrow, oh what fun it all would be.
Then what's to stop us, pretty baby. But What Is And What Should Never Be.
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