/sci/ - Science & Math

>>6916013

>how does displacement current tie into relativity?

I’ll assume you mean “special relativity”? Classical electromagnetism was codified by Maxwell in the form of Maxwell’s equations. These describe all electromagnetic phenomena. When compiling the equations, Maxwell noticed what looked like an inherit symmetry between magnetism and electricity, save for one missing “electric” term. In a stroke of genius, Maxwell decided to add this term, “displacement current”, aka rate of change of electric displacement field, even though there wasn’t really any physical evidence for it at the time. This caused some controversy (we eventually did find physical evidence for it, aka electromagnetic waves).

At some point Einstein came along and formulated special relativity. For something to be compatible with special reality it needs to be lorentz invariant. Remarkably, Classical electromagnetism was already lorentz invariant! It was automatically compatible with special relativity, because of Maxwell’s extra term! Einstein even published exactly how this all works, and how the symmetries works. It turns of that the “displacement current” and the “magnetic intensity” are basically symmetric to each other, in term so special relativity.