Editing Pauli exclusion principle (section)

=== Astrophysics ===
Dyson and Lenard did not consider the extreme magnetic or gravitational forces that occur in some [[astronomical]] objects. In 1995 [[Elliott Lieb]] and coworkers showed that the Pauli principle still leads to stability in intense magnetic fields such as in [[neutron star]]s, although at a much higher density than in ordinary matter.<ref>{{cite journal |first1=E. H. |last1=Lieb |first2=M. |last2=Loss |first3=J. P. |last3=Solovej |journal=[[Physical Review Letters]] |volume=75 |issue=6 |pages=985–9 |year=1995 |title=Stability of Matter in Magnetic Fields |doi=10.1103/PhysRevLett.75.985 |pmid=10060179 |arxiv = cond-mat/9506047 |bibcode = 1995PhRvL..75..985L |s2cid=2794188 }}</ref> It is a consequence of [[general relativity]] that, in sufficiently intense gravitational fields, matter collapses to form a [[black hole]].

Astronomy provides a spectacular demonstration of the effect of the Pauli principle, in the form of [[white dwarf]] and [[neutron star]]s. In both bodies, the atomic structure is disrupted by extreme pressure, but the stars are held in [[hydrostatic equilibrium]] by ''[[degeneracy pressure]]'', also known as Fermi pressure. This exotic form of matter is known as [[degenerate matter]]. The immense gravitational force of a star's mass is normally held in equilibrium by [[Ideal gas law|thermal pressure]] caused by heat produced in [[thermonuclear fusion]] in the star's core. In white dwarfs, which do not undergo nuclear fusion, an opposing force to gravity is provided by [[electron degeneracy pressure]]. In [[neutron star]]s, subject to even stronger gravitational forces, electrons have merged with protons to form neutrons. Neutrons are capable of producing an even higher degeneracy pressure, [[neutron degeneracy pressure]], albeit over a shorter range. This can stabilize neutron stars from further collapse, but at a smaller size and higher [[density]] than a white dwarf. Neutron stars are the most "rigid" objects known; their [[Young modulus]] (or more accurately, [[bulk modulus]]) is 20 orders of magnitude larger than that of [[diamond]]. However, even this enormous rigidity can be overcome by the [[gravitational field]] of a neutron star mass exceeding the [[Tolman–Oppenheimer–Volkoff limit]], leading to the formation of a [[black hole]].<ref name="Bojowald2012">{{cite book|author=Martin Bojowald|title=The Universe: A View from Classical and Quantum Gravity|date=5 November 2012|publisher=John Wiley & Sons|isbn=978-3-527-66769-7}}</ref>{{rp|286–287}}