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A thorough extant study of the anthropic principle is the book The anthropic cosmological principle by John D. Barrow, a cosmologist, and Frank J. Tipler, a cosmologist and mathematical physicist. This book sets out in detail the many known anthropic coincidences and constraints, including many found by its authors.
Al-Biruni and Al-Khazini studied the theory of the centre of gravity, and generalized and applied it to three-dimensional bodies. Fine experimental methods were also developed for determining the specific gravity or specific weight of objects, based the theory of balances and weighing .
In physics, gravity (from Latin gravitas 'weight' [1]) is a fundamental interaction primarily observed as a mutual attraction between all things that have mass.Gravity is, by far, the weakest of the four fundamental interactions, approximately 10 38 times weaker than the strong interaction, 10 36 times weaker than the electromagnetic force, and 10 29 times weaker than the weak interaction.
Flights of Fancy talks about almost every aspect of flying–all the different ways of defying gravity–in imagination and in technology, in humans and in animals. It ranges over many instances of flight including the Wright brothers, Greek mythology, extinct and living birds, helicopters, insects, bats, and flying squirrels.
Before Newton's law of gravity, there were many theories explaining gravity. Philoshophers made observations about things falling down − and developed theories why they do – as early as Aristotle who thought that rocks fall to the ground because seeking the ground was an essential part of their nature.
While there are promising candidates for such a theory of quantum gravity, notably string theory and loop quantum gravity, there is at present no consistent and complete theory. It has long been hoped that a theory of quantum gravity would also eliminate another problematic feature of general relativity: the presence of spacetime singularities ...
The book is still considered influential in the physics community, with generally positive reviews, but with some criticism of the book's length and presentation style. To quote Ed Ehrlich: [4] 'Gravitation' is such a prominent book on relativity that the initials of its authors MTW can be used by other books on relativity without explanation.
1902 – Paul Gerber explains the movement of the perihelion of Mercury using finite speed of gravity. [31] His formula, at least approximately, matches the later model from Einstein's general relativity, but Gerber's theory was incorrect. 1902 – Henri Poincaré questions the concept of simultaneity in his book, Science and Hypothesis. [32] [33]