# Lecture 6

This lecture is about how the laws of nature have to be written in terms of tensors if we want them to be the same in all reference frames, the basic requirement of relativity.

We show that scalars and four-vectors are rank-zero and rank-one tensors, respectively and then develop the notion of higher rank tensors.

I have also included a section on relativistic kinematics which is not actually in the lecture, where I cover proper acceleration.