Greg Egan is really good for this. He has a couple books where the whole premise is "what would happen if we changed the laws of physics?" For example, his "Orthogonal" series takes place in a universe where the metric of spacetime is Euclidean (in our universe it is Minkowski), meaning there's no fundamental difference between space and time. This changes the way that many things work like the nature of light, electomagetism, thermodynamics, and space flight. In the appendix he has legit equations and derivations to back up the stuff he is describing. It's all very impressive and a little mind-bending, and I'm a physicist myself!