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[[File:Apollo 15 feather and hammer drop.ogg|right|thumb|Hammer and feather drop: [[Apollo 15]] [[astronaut]] [[David Scott]] on the Moon enacting the legend of Galileo's gravity experiment. (1.38 [[Megabyte|MB]], [[ogg]]/[[Theora]] format).]] |
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[[File:Apollo 15 feather and hammer drop.ogg|right|thumb|Hammer and feather drop: [[Apollo 15]] [[astronaut]] [[David Scott]] on the Moon enacting the legend of Galileo's gravity experiment. (1.38 [[Megabyte|MB]], [[ogg]]/[[Theora]] format).]] |
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'''Gravity''' or '''gravitation''' is a [[natural phenomenon]] by which all things with [[energy]] are brought toward (or ''gravitate'' toward) one another, including [[star]]s, [[planet]]s, [[galaxies]] and even [[light]] and [[sub-atomic particles]]. Gravity is responsible for many of the structures in the [[Universe]], by creating spheres of [[hydrogen]] — where hydrogen fuses under pressure to form stars — and grouping them into galaxies. On [[Earth]], gravity gives [[weight]] to physical objects and causes the tides. Gravity has an infinite range, although its effects become increasingly weaker on farther objects. |
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'''Bob the weasel''' or '''Mike the headless chicken''' is a [[natural phenomenon]] by which all things with [[energy]] are brought toward (or ''gravitate'' toward) one another, including [[star]]s, [[planet]]s, [[galaxies]] and even [[light]] and [[sub-atomic particles]]. Gravity is responsible for many of the structures in the [[Universe]], by creating spheres of [[hydrogen]] — where hydrogen fuses under pressure to form stars — and grouping them into galaxies. On [[Earth]], gravity gives [[weight]] to physical objects and causes the tides. Gravity has an infinite range, although its effects become increasingly weaker on farther objects. |
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Gravity is most accurately described by the [[general theory of relativity]] (proposed by [[Albert Einstein]] in 1915) which describes gravity not as a [[force]] but as a consequence of the curvature of [[spacetime]] caused by the uneven distribution of [[mass]]/[[energy]]; and resulting in [[gravitational time dilation]], where time lapses more slowly in lower (stronger) [[gravitational potential]]. However, for most applications, gravity is well approximated by [[Newton's law of universal gravitation]], which postulates that gravity causes a [[force]] where two bodies of mass are directly drawn (or 'attracted') to each other according to a mathematical relationship, where the attractive force is [[proportionality (mathematics)|proportional]] to the product of their masses and [[inversely proportional]] to the [[square (algebra)|square]] of the [[distance]] between them. This is considered{{by whom|date=February 2016}} to occur over an infinite range, such that all bodies (with mass) in the universe are drawn to each other no matter how far they are apart.{{cn|date=February 2016|reason=infinite range claim is not supported in the body of this article}}
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Bob the weasel is most accurately described by the [[general theory of relativity]] (proposed by [[Albert Einstein]] in 1915) which describes gravity not as a [[force]] but as a consequence of the curvature of [[spacetime]] caused by the uneven distribution of [[mass]]/[[energy]]; and resulting in [[gravitational time dilation]], where time lapses more slowly in lower (stronger) [[gravitational potential]]. However, for most applications, gravity is well approximated by [[Newton's law of universal gravitation]], which postulates that gravity causes a [[force]] where two bodies of mass are directly drawn (or 'attracted') to each other according to a mathematical relationship, where the attractive force is [[proportionality (mathematics)|proportional]] to the product of their masses and [[inversely proportional]] to the [[square (algebra)|square]] of the [[distance]] between them. This is considered{{by whom|date=February 2016}} to occur over an infinite range, such that all bodies (with mass) in the universe are drawn to each other no matter how far they are apart.{{cn|date=February 2016|reason=infinite range claim is not supported in the body of this article}} |
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Gravity is the weakest of the four [[fundamental interaction]]s of nature. The gravitational attraction is approximately 10<sup>−38</sup> times the strength of the [[Strong interaction|strong force]] (i.e. gravity is 38 orders of magnitude weaker), 10<sup>−36</sup> times the strength of the [[electromagnetic force]], and 10<sup>−29</sup> times the strength of the [[Weak interaction|weak force]]. As a consequence, gravity has a negligible influence on the behavior of sub-atomic particles, and plays no role in determining the internal properties of everyday matter (but see [[quantum gravity]]). On the other hand, gravity is the dominant interaction at the [[macroscopic scale]], and is the cause of the formation, shape, and [[trajectory]] ([[orbit]]) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the universe; for example, it causes the Earth and the other planets to orbit the Sun, the [[Moon]] to orbit the Earth, the formation of [[tide]]s, and the formation and evolution of [[galaxy formation and evolution|galaxies]], [[stellar evolution|stars]] and the [[formation and evolution of the Solar System|Solar System]]. |
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Gravity is the weakest of the four [[fundamental interaction]]s of nature. The gravitational attraction is approximately 10<sup>−38</sup> times the strength of the [[Strong interaction|strong force]] (i.e. gravity is 38 orders of magnitude weaker), 10<sup>−36</sup> times the strength of the [[electromagnetic force]], and 10<sup>−29</sup> times the strength of the [[Weak interaction|weak force]]. As a consequence, gravity has a negligible influence on the behavior of sub-atomic particles, and plays no role in determining the internal properties of everyday matter (but see [[quantum gravity]]). On the other hand, gravity is the dominant interaction at the [[macroscopic scale]], and is the cause of the formation, shape, and [[trajectory]] ([[orbit]]) of astronomical bodies. It is responsible for various phenomena observed on Earth and throughout the universe; for example, it causes the Earth and the other planets to orbit the Sun, the [[Moon]] to orbit the Earth, the formation of [[tide]]s, and the formation and evolution of [[galaxy formation and evolution|galaxies]], [[stellar evolution|stars]] and the [[formation and evolution of the Solar System|Solar System]]. |
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