Gravitation

Gravitation is a natural phenomenon by which all objects with mass attract each other, and is one of the fundamental forces of physics. In everyday life, gravitat6:00 PM 2/16/2008ion is most commonly thought of as the agency that gives objects weight. 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 convection for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Gravitation is also the reason for the very existence of the Earth, the Sun, and most macroscopic objects in the universe; without it, matter would not have coalesced into these large masses and life, as we know it, would not exist.

Modern physics describes gravitation using the general theory of relativity, but the much simpler Newton's law of universal gravitation provides an excellent approximation in most cases.

The terms gravitation and gravity are mostly interchangeable in everyday use, but in scientific usage a distinction may be made. "Gravitation" is a general term describing the attractive influence that all objects with mass exert on each other, while "gravity" specifically refers to a force that is supposed in some theories to be the cause of this attraction. By contrast, in general relativity gravitation is due to spacetime curvatures that cause inertially moving objects to accelerate towards each other.

Efforts to understand gravity began in ancient times. Philosophers in ancient India explained the phenomenon from the 8th century BC.According to Kanada, founder of the Vaisheshika school, "Weight causes falling; it is imperceptible and known by inference."

In the 4th century BC, the Greek philosopher Aristotle believed that there was no effect without a cause, and therefore no motion without a force. He hypothesized that everything tried to move towards its proper place in the crystalline spheres of the heavens, and that physical bodies fell toward the center of the Earth in proportion to their weight.

Brahmagupta, in the Brahmasphuta Siddhanta , responded to critics of the heliocentric system of Aryabhata stating that "all heavy things are attracted towards the center of the earth" and that "all heavy things fall down to the earth by a law of nature, for it is the nature of the earth to attract and to keep things, as it is the nature of water to flow, that of fire to burn, and that of wind to set in motion... The earth is the only low thing, and seeds always return to it, in whatever direction you may throw them away, and never rise upwards from the earth."

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Teenage Mutant Ninja Turtles

The Teenage Mutant Ninja Turtles are a fictional team of four anthropomorphic turtle mutants, who are trained by their sensei, Master Splinter, to become skilled Ninja warriors. From their home in the sewers of Manhattan, they battle petty criminals, evil megalomaniacs, and alien invaders, all while remaining isolated from society at large. The characters initially appeared in comic books before being licensed for toys, cartoons and film adaptations.

The Teenage Mutant Ninja Turtles originated in an American comic book published by Mirage Studios in 1984. The concept arose from a humorous drawing sketched out by Kevin Eastman during a casual evening of brainstorming with his friend Peter Laird. Using money from a tax refund together with a loan from Eastman's uncle, the young artists self-published a single issue comic intended to parody four of the most popular comics of the early 1980s: Marvel Comics' Daredevil and New Mutants, Dave Sim's Cerebus and Frank Miller's Ronin.

Much of the Turtles' mainstream success is owed to a licensing agent, Mark Freedman, who sought out Eastman and Laird to propose wider merchandising opportunities for the offbeat property. In 1986, Dark Horse Miniatures produced a set of 15 mm lead figurines. In January 1988, they visited the offices of Playmates Toys Inc, a small California toy company who wished to expand into the action figure market. Accompanied by the popular Teenage Mutant Ninja Turtles animated series, the TMNT were soon catapulted into pop culture history. At the height of the frenzy, in the late 1980s and early 1990s, the Turtles' likenesses could be found on a wide range of children's merchandise, from PEZ dispensers to skateboards, breakfast cereal, toothpaste, school supplies and cameras. The original cartoon series was featured on VH1's I Love The 80's and the toys based upon the show were ranked 33 in I Love Toys.

The first issue of Eastman and Laird's Teenage Mutant Ninja Turtles premiered in May, 1984, at a comic book convention held at a local Sheraton Hotel in Portsmouth, New Hampshire. It was published by Mirage Studios in an oversized magazine-style format using black & white artwork on cheap newsprint, limited to a print run of only 3,000 copies. The small print runs made these early comics instant collector items, and within months they were trading for over fifty times their cover price. The name "Mirage Studios" was chosen because of Eastman and Laird's lack of a professional art studio at the start of their career, before their creation made them both multi-millionaires.

Mirage also published a bi-monthly companion book entitled Tales of the Teenage Mutant Ninja Turtles, featuring art by Ryan Brown and Jim Lawson, which was designed to fill in the gaps of continuity in the TMNT universe. The title ran from 1987-1989, released in alternating months with the regular Eastman & Laird book.

As the TMNT phenomenon proliferated to other media, Eastman and Laird would find themselves administrating an international merchandising juggernaut. Unfortunately, this prevented the two creators from participating in the day-to-day work of writing and illustrating a monthly comic book. For this reason, many guest artists were invited to showcase their unique talents in the TMNT universe. The breadth of diversity found in the various short stories gave the series a disjointed, anthology-like feel. Fans stuck with the series, and what was originally intended as a one-shot parody became a continuing series that lasted for 76 issues spanning two separate volumes.

In June, 1996, Image Comics revived the title as a more action-oriented TMNT series. Although notable for inflicting major physical changes on the main characters, the events of Volume 3 have been dropped from continuity. Mirage Studios resumed publication of a fourth volume in December, 2001, under the simple title TMNT. After the publication of issue #28, writer Peter Laird placed the series on an eight month hiatus to devote himself to production of the recent TMNT movie. However, after that eight months had passed Mirage's official website went on to list the series as in "indefinite hiatus". In January 2008 Mirage had finally confirmed that the series would return in May 2008.

Teenage Mutant Ninja Turtles Adventures was a comic book series published from August 1988 to October 1995 by Archie Comics. The initial storylines were close adaptations of the 1987 animated series, but with the fifth issue Eastman and Laird decided to hand the series over to Mirage Studios employees Ryan Brown and Stephen Murphy who immediately abandoned the animated series adaptations and took the title in a decidedly different direction with all-new original adventures.

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