Because astrophysics is a broad subject , astrophysicists typically apply many disciplines of physics , including mechanics , electromagnetism , statistical mechanics , thermodynamics , quantum mechanics , relativity , nuclear and particle physics , and atomic and molecular physics .
Modern physics is a term normally used to cover fields which rely on quantum theory , including quantum mechanics , atomic physics , nuclear physics , particle physics and condensed matter physics , as well as the more modern fields of general and special relativity .