Let’s go for it.įeynman deals with the matter of the speed of an electromagnetic wave, and the speed of light, in a rather complicated exposé on the fields from some infinite sheet of charge that is suddenly set into motion, parallel to itself, as shown below. Sure, smart-arse! Let me be more precise: how can we relate the speed of light to Maxwell’s equations? That is the question here. It’s light, so it travels at the speed of light. You’ll immediately say: that’s a nonsensical question. In this post, I’ll focus on the speed of light: why do electromagnetic waves – light – travel at the speed of light?
However, they’re pretty horrendous to read, and so I just want to summarize them a bit-if only for myself, so as to remind myself what’s important and not. In my post on the Lorentz gauge, I included a few links to Feynman’s Lecturesthat explain the nitty-gritty of this mechanism from various angles. You know that by now – indeed, you’ve heard this a thousand times before – but, if you’re reading this, you want to know how it works exactly. some moving charge, but then the electromagnetic wave travels, all by itself, through empty space, completely detached from the cause. So we need some First Cause to get it all started ? i.e. We know how electromagnetic waves travel through space: they do so because of the mechanism described in Maxwell’s equation: a changing magnetic field causes a changing electric field, and a changing magnetic field causes a ( changing) electric field, as illustrated below. In addition, I note the dark force has amused himself by removing some material, which messed up the lay-out of this post as well. Pre-script (dated 26 June 2020): Our ideas have evolved into a full-blown realistic (or classical) interpretation of all things quantum-mechanical.