Electron degenerate matter is a form of degenerate matter in which the weight of overlying material tries to force all of the electrons surrounding the atomic nucleus into the lowest energy quantum state. The electrons resist, because of the Paul exclusion principle, and so exert a pressure, known as degenerate electron pressure or electron degeneracy pressure, that halts further collapse. This pressure is sufficient up to the Chandrasekar limit of about 1.4 solar masses. However, beyond this critical mass, gravity overwhelms the degeneracy pressure and results in further collapse.