Fly By Night Physics

by Anthony Zee Very good. Learned a lot. Need to read more his stuff!

There are only three dimensions: Mass, Length and Time. Nobody knows why there are three and only three.

That fact that we have three fundamental constants of nature; GN, c, hbar, means we can describe all of these dimensions in natrual scale. Suggests we have found all the core physics principles ?

By using energy conservation you effectively integrated the equations of motion to turn a second derivative in time into the square of a first derivative.

Einstein used symmetry to determine the laws of motion. Before him, physicists determined the laws of motion and looked at them to see which symmetries where relevant.