Abstract

Our most fundamental physical theories turn out to be the most tightly constrained. There are more mathematical restrictions on quantum mechanics than on classical mechanics, and many more restrictions on relativity than on non-relativistic dynamics. In this talk, I will describe this steady march towards a maximally constrained (hopefully unique) theory of everything, and give an example of how to put this perspective into practice: namely the calculation of the classical gravitational waves emitted by two black holes merging (which turns out to be much easier if you first quantise everything, make use of how constrained quantum mechanics is, and take the classical limit only at the very end).