Editing Gravity (section)

{{Short description|Attraction of masses and energy}}
{{Other uses}}
{{redirect-multi|2|Gravitation|Law of Gravity}}
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{{Use American English|date=December 2024}}
{{Use dmy dates|date=December 2024}}
[[File:UGC 1810 and UGC 1813 in Arp 273 (captured by the Hubble Space Telescope).jpg|thumb|upright=1.35|The shapes of two massive [[galaxies]] in this image are due to gravity.]]
{{Classical mechanics}}

In physics, '''gravity''' ({{Etymology|lat|gravitas|weight}}<ref>{{Cite web |url=https://browse.dict.cc/latin-english/gravitas.html |title=dict.cc dictionary :: gravitas :: English-Latin translation |access-date=11 September 2018 |archive-date=13 August 2021 |archive-url=https://web.archive.org/web/20210813203625/https://browse.dict.cc/latin-english/gravitas.html |url-status=live }}</ref>), also known as '''gravitation''' or a '''gravitational interaction''',<ref>{{cite book |title=Particles and Fundamental Interactions: An Introduction to Particle Physics |edition=illustrated |first1=Sylvie |last1=Braibant |first2=Giorgio |last2=Giacomelli |first3=Maurizio |last3=Spurio |publisher=Springer Science & Business Media |year=2011 |isbn=9789400724631 |page=109 |url=https://books.google.com/books?id=0Pp-f0G9_9sC}} [https://books.google.com/books?id=0Pp-f0G9_9sC&pg=PA109 Extract of page 109]</ref> is a [[fundamental interaction]], a mutual attraction between all massive particles. [[Gravity of Earth|On Earth]], gravity takes a slightly different meaning: the observed force between objects and the Earth. This force is dominated by the combined gravitational interactions of particles but also includes effect of the Earth's rotation.<ref name=HWM/> Gravity gives [[weight]] to [[physical object]]s and is essential to understanding the mechanisms responsible for surface water [[gravity waves|waves]] and lunar [[tide]]s. Gravity also has many important biological functions, helping to guide the growth of plants through the process of [[gravitropism]] and influencing the [[Circulatory system|circulation]] of fluids in [[multicellular organism]]s.

The gravitational attraction between primordial [[hydrogen]] and clumps of [[dark matter]] in the early [[universe]] caused the hydrogen gas to [[coalescence (physics)|coalesce]], eventually condensing and fusing to [[star formation|form stars]]. At larger scales this results in galaxies and clusters, so gravity is a primary driver for the large-scale structures in the universe. Gravity has an infinite range, although its effects become weaker as objects get farther away.

Gravity is accurately described by the [[general relativity|general theory of relativity]], proposed by [[Albert Einstein]] in 1915, which describes gravity in terms of the [[curvature]] of [[spacetime]], caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a [[black hole]], from which nothing—not even light—can escape once past the black hole's [[event horizon]].<ref>{{Cite web|url=http://hubblesite.org/explore_astronomy/black_holes/home.html|title=HubbleSite: Black Holes: Gravity's Relentless Pull|website=hubblesite.org|access-date=7 October 2016|archive-date=26 December 2018|archive-url=https://web.archive.org/web/20181226185228/http://hubblesite.org/explore_astronomy/black_holes/home.html|url-status=live}}</ref> However, for most applications, gravity is well approximated by [[Newton's law of universal gravitation]], which describes gravity as a [[force]] causing any two bodies to be attracted toward each other, with magnitude [[proportionality (mathematics)|proportional]] to the product of their masses and [[inversely proportional]] to the [[square (algebra)|square]] of the [[distance]] between them.

Scientists are currently working to develop a theory of gravity consistent with [[quantum mechanics]], a quantum gravity theory,<ref name="NYT-20221010">{{cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |date=10 October 2022 |title=Black Holes May Hide a Mind-Bending Secret About Our Universe – Take gravity, add quantum mechanics, stir. What do you get? Just maybe, a holographic cosmos. |url=https://www.nytimes.com/2022/10/10/science/black-holes-cosmology-hologram.html |url-status=live |archive-url=https://web.archive.org/web/20221116151210/https://www.nytimes.com/2022/10/10/science/black-holes-cosmology-hologram.html |archive-date=16 November 2022 |accessdate=10 October 2022 |work=[[The New York Times]]}}</ref> which would allow gravity to be united in a common mathematical framework (a [[theory of everything]]) with the other three fundamental interactions of physics. Although experiments are now being conducted to prove (or disprove) whether gravity is quantum, it is not known with certainty.<ref>{{Cite news |last=Cartwright |first=Jon |date=May 17,2025 |title=Defying gravity |work=New Scientist |publisher=New Scientist Limited |pages=30–33}}</ref>