Editing Gravity (section)

=== Stars and black holes ===
{{main|Star formation}}
During star formation, gravitational attraction in a cloud of hydrogen gas competes with thermal gas pressure. As the gas density increases, the temperature rises, then the gas radiates energy, allowing additional gravitational condensation. 
If the mass of gas in the region is low, the process continues until a [[brown dwarf]] or [[gas-giant planet]] is produced. If more mass is available, the additional gravitational energy allows the central region to reach pressures sufficient for [[nuclear fusion]], forming a [[star]]. In a star, again the gravitational attraction competes,  with thermal and radiation pressure
in [[hydrostatic equilibrium]] until the star's atomic fuel runs out. The next phase depends upon the total mass of the star. Very low mass stars slowly cool as [[white dwarf]] stars with a small core balancing gravitational attraction with [[electron degeneracy pressure]]. Stars with masses similar to the Sun go through a [[red giant]] phase before becoming white dwarf stars. Higher mass stars have complex core structures that burn helium and high atomic number elements ultimately producing an [[iron]] core. As their fuel runs out these stars become unstable producing [[supernova]]. The result can be a [[neutron star]] where gravitational attraction balances [[neutron degeneracy pressure]] or, for even higher masses, a [[black hole]] where gravity operates alone with such intensity that even light cannot escape.<ref>{{Cite web |last=Demtröder |first=Wolfgang |date=2024 |title=Birth, Lifetime and Death of Stars |url=https://link.springer.com/10.1007/978-3-031-22135-4_5 |access-date=2025-05-04 |publisher=Springer Nature Switzerland |pages=121–175 |language=en |doi=10.1007/978-3-031-22135-4_5}}</ref>{{rp|121}}