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Gravity
Gravity or gravitation is a natural phenomenon by which all objects are brought towards one another, including stars, planets, galaxies and sub-atomic particles. Gravity is responsible for many of the structures in the Universe. It creates spheres of hydrogen, where hydrogen fuses under pressure and forms stars - and groups 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 more distant objects.
For most applications, gravity is well approximated by Newton's law of universal gravitation. It postulates that gravity causes a force where two bodies of mass are directly drawn (or 'attracted') to each other according to a mathematical relationship: the attractive force is proportional to the product of their masses. However, gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915). It describes gravity not as a force but as a consequence of the curvature of space-time that is caused by the uneven distribution of mass and energy.
Without Gravity: The force of gravity includes for example the force that causes a ball you throw in the air to come down again; the force that causes a car to drive downhill even when you aren't stepping on the gas; the force that causes a glass you drop to fall to the floor; the force that causes your drink to rest on the bottom of your glass instead of hovering near the top of your glass; the force that causes an apple to fall down from an apple tree; the force that keeps you walking on the ground instead of flying away into space etc. Maybe there are phenomena on earth, where the rules of gravity do not apply. Living in a place without gravity for a longer period can also have major impacts on the human body.

Gravity, Gravitation, Newton, Einstein, Planets, Energy

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