Gravitation

Gravitation, or gravity, is a natural phenomenon by which all physical bodies attract each other.

It is what the film Gravity is named after and is prominent in the film due to the fact that it is set in the zero-gravity of space and accurately portrays how it works. 

Contrary to popular belief, however, Gravity is not named after the zero-gravity of space but rather the gravity Dr. Stone experiences again on Earth. 

Description and Effects

It is most commonly experienced as the agent that gives weight to objects with mass and causes them to fall to the ground when dropped. Gravitation is one of the four fundamental interactions of nature, along with electromagnetism, and the nuclear strong force and weak force. In modern physics, the phenomenon of gravitation is most accurately described by the general theory of relativity by Einstein, in which the phenomenon itself is a consequence of the curvature of spacetime governing the motion of inertial objects. The simpler Newton's law of universal gravitation postulates the gravity force proportional to masses of interacting bodies and inversely proportional to the square of the distance between them. It provides an accurate approximation for most physical situations including calculations as critical as spacecraft trajectory. From a cosmological perspective, gravitation causes dispersed matter to coalesce, and coalesced matter to remain intact, thus accounting for the existence of planets, stars, galaxies and most of the macroscopic objects in the universe. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for natural convection, by which fluid flow occurs under the influence of a density gradient and gravity; for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena observed on Earth and throughout the universe.