Electron Degeneracy Pressure

The force that supports white dwarf stars against gravity. Quantum mechanics restricts the number of electrons that can have low energy. When electrons are packed together, the number of available low energy states is too small and many electrons are forced into high energy states. When this happens the electrons are said to be degenerate and make a significant contribution to pressure. This electron degeneracy pressure arises from quantum mechanical effects and is insensitive to temperature, i.e., the pressure doesn’t go down as the star cools.

Some or all content above used with permission from J. H. Wittke.