Electron degeneracy pressure is a force caused by the Pauli exclusion principle, which states that two electrons cannot occupy the same quantum state at the same time. In physics, a force is anything that causes a free body with mass to accelerate. ... The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925, which states that no two identical fermions may occupy the same quantum state simultaneously. ... Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... A quantum state is any possible state in which a quantum mechanical system can be. ...

Also relevant to the understanding of electron degeneracy pressure is the Heisenberg uncertainty principle, which states that In quantum physics, the Heisenberg uncertainty principle, sometimes called the Heisenberg indeterminacy principle, expresses a limitation on accuracy of (nearly) simultaneous measurement of observables such as the position and the momentum of a particle. ...

where is Planck's constant (h) divided by 2π and Δx is the uncertainty of the position measurements and Δp is the uncertainty in the standard deviation of the momentum measurements. Plancks constant, denoted h, is a physical constant that is used to describe the sizes of quanta. ... Lower-case Ï€ (the lower case letter is usually used for the constant) The mathematical constant Ï€ is an irrational number, approximately equal to 3. ...

As pressure increases ever more, the uncertainty in position measurements, Δx, becomes ever smaller. Thus, as dictated by the uncertainty principle, the uncertainty in the momenta of the electrons, Δp, becomes larger. Thus, no matter how low the temperature drops, the electrons must be travelling at this "Heisenberg speed," contributing to the pressure. When the pressure due to the "Heisenberg speed" exceeds that of the pressure from the thermal motions of the electrons, the electrons are labeled as degenerate.

Electron degeneracy pressure is the pressure that keeps a white dwarf star from collapsing. When the electrons are degenerate, degenerate matter is formed. In the case of a gravitational collapse of a star, depending on the initial mass of the star, electron degeneracy pressure can affect the final evolutionary state of the collapsing star. For example, a star with initial mass exceeding the mass stated by the Chandrasekhar Limit will continue to collapse and may form neutron stars or black holes because the degeneracy pressure provided by the electrons are much weaker than the inward gravitational force. White dwarf Sirius-B in x-rays A white dwarf is an astronomical object which is produced when a low or medium mass star dies. ... Degenerate matter is matter which has sufficiently high density that the dominant contribution to its pressure arises from the Pauli exclusion principle. ... The Chandrasekhar limit, is the maximum mass possible for a white dwarf (one of the end stages of stars when they cool down) and is approximately 3 × 1030 kg, around 1. ...