Gravity, or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars and light—are brought toward one another. On Earth, gravity gives weight to physical objects, the Moon's gravity causes the ocean tides; the gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing, forming stars—and for the stars to group together into galaxies—so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become weaker as objects get further away. Gravity is most described by the general theory of relativity which describes gravity not as a force, but as a consequence 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 light—can escape once past the black hole's event horizon. However, for most applications, gravity is well approximated by Newton's law of universal gravitation, which describes gravity as a force which causes any two bodies to be attracted to each other, with the force proportional to the product of their masses and inversely proportional to the square of the distance between them.

Gravity is the weakest of the four fundamental interactions of physics 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, is the cause of the formation and trajectory of astronomical bodies; the earliest instance of gravity in the Universe in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework with the other three fundamental interactions of physics, are a current area of research.

The ancient Greek philosopher Archimedes discovered the center of gravity of a triangle. He postulated that if two equal weights did not have the same center of gravity, the center of gravity of the two weights together would be in the middle of the line that joins their centers of gravity; the Roman architect and engineer Vitruvius in De Architectura postulated that gravity of an object did not depend on weight but its "nature". In ancient India, Aryabhata first identified the force to explain why objects are not thrown outward as the earth rotates. Brahmagupta described gravity as an attractive force and used the term "gurutvaakarshan" for gravity. Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and early 17th centuries. In his famous experiment dropping balls from the Tower of Pisa, with careful measurements of balls rolling down inclines, Galileo showed that gravitational acceleration is the same for all objects; this was a major departure from Aristotle's belief that heavier objects have a higher gravitational acceleration.

Galileo postulated air resistance as the reason that objects with less mass fall more in an atmosphere. Galileo's work set the stage for the formulation of Newton's theory of gravity. In 1687, English mathematician Sir Isaac Newton published Principia, which hypothesizes the inverse-square law of universal gravitation. In his own words, "I deduced that the forces which keep the planets in their orbs must reciprocally as the squares of their distances from the centers about which they revolve: and thereby compared the force requisite to keep the Moon in her Orb with the force of gravity at the surface of the Earth; the equation is the following: F = G m 1 m 2 r 2 Where F is the force, m1 and m2 are the masses of the objects interacting, r is the distance between the centers of the masses and G is the gravitational constant. Newton's theory enjoyed its greatest success when it was used to predict the existence of Neptune based on motions of Uranus that could not be accounted for by the actions of the other planets.

Calculations by both John Couch Adams and Urbain Le Verrier predicted the general position of the planet, Le Verrier's calculations are what led Johann Gottfried Galle to the discovery of Neptune. A discrepancy in Mercury's orbit pointed out flaws in Newton's theory. By the end of the 19th century, it was known that its orbit showed slight perturbations that could not be accounted for under Newton's theory, but all searches for another perturbing body had been fruitless; the issue was resolved in 1915 by Albert Einstein's new theory of general relativity, which accounted for the small discrepancy in Mercury's orbit. This discrepancy was the advance in the perihelion of Mercury of 42.98 arcseconds per century. Although Newton's theory has been superseded by Einstein's general relativity, most modern non-relativistic gravitational calculations are still made using Newton's theory because it is simpler to work with and it gives sufficiently acc


Plentong is a mukim in Johor Bahru District, Malaysia. It began as a Kangchu settlemement known as Tey Chu Kang in 1859 and an old Chinese new village, now a busy town in Johor. Mukim Plentong which covers Permas Jaya, Pasir Gudang etc. is the most populous mukim in Johor and one of the most populous in Malaysia with over 500,000 residents. It covers an area of 202 km2. Plentong village suffered extensive flooding due to a poor water drainage system; the government cooperated with KTM Berhad to rebuild the KTM Plentong Bridge in order to facilitate the flow of Sungai Plentong during rainy season. The whole project cost about 50 million and as of July 2009, the train bridge is in the early stage of construction. Plentong is the headquarters of the Malacca-Johor archdiocese, known as Majodi centre and has a Catholic Saint Joseph Church. Other places of worship include Hindu temples and Chinese clan temples. One of the largest granite quarries in Johor is located nearby, it houses the Permas Jaya Bridge.

The area is accessible by Muafakat Bus route P-301

Human possession in science fiction

Human possession in science fiction is an extension within science-fiction literature and film of the mythology of human possession found in many cultures throughout human history. Possession in science fiction involves extraterrestrial parasitic organisms that can take control of a human host. During the Cold War era in the western world, this was a metaphor for the threat of communism. In Robert Heinlein's novel The Puppet Masters, slugs from Titan, the largest of Saturn's moons, can take over human bodies and know everything their hosts know. In the Animorphs universe created by author K. A. Applegate, the yeerks are a parasitic species capable of controlling human beings and compatible other species. Individuals controlled by yeerks are known as "controllers." Yeerks have access to the memories and personalities of their hosts, can exist undetected by friends and family. The Yeerks are conquerors, use infestation as a means of infiltration on still-unconquered worlds. Yeerks can easily move from one host to another, in fact have to leave their hosts in order to feed on kandrona rays.

In Invaders from Mars, mind-control crystals at the base of the skull enable the Martians to turn their victims into saboteurs. In the Star Trek universe, the Trill are a symbiotic pair of species consisting of parasites and hosts; the Trill Dax is a main character in Star Trek: Deep Space Nine, first joined with Jadzia Dax after she is killed, with Ezri Dax. The parasitic species can control human beings, but not for extended periods of time. In the Stargate universe, the Goa'uld are a parasitic species which can control human beings and other compatible species; the Goa'uld forcibly take hosts, whereas the Tok'ra, though the same species, exist consensually as symbiotic beings with their hosts. Goa'uld have access to the memories and personalities of their hosts, can exist undetected by friends and family. Goa'uld are power-hungry and take on the roles of gods from the mythologies of the humans that they infest. Infestation is used as a means of infiltration or access to information. Goa'uld can move from one host with some difficulty.

Goa'uld have the ability to kill or torture their hosts. Parasitism in fiction supernatural possession