Lecture 2 & 3 YouTube

It's generally accepted that this lecture comes between Lecture 7 and Lecture 8, even though it's titled Lecture 2 & 3 online.

This is the final lecture on special relativity (the last two lectures touch upon the general theory), and covers both the vacuum and non-vacuum versions of Maxwell's equations.

We show how the eight separate equations can be written in tensor notation, specifically in terms of the Faraday tensor, which appears in the relativistic Lorentz force law.

This allows to say that Maxwell's equations are valid laws of nature, since they have the same form in all reference frames. Furthermore, since they predict a value for the speed of light, this too must be the same in all reference frames.