This article is a non-technical introduction to the subject. For the main einstein’s general theory of relativity original paper pdf article, see General relativity. General relativity is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915.
According to general relativity, the observed gravitational effect between masses results from their warping of spacetime. By the beginning of the 20th century, Newton’s law of universal gravitation had been accepted for more than two hundred years as a valid description of the gravitational force between masses. In Newton’s model, gravity is the result of an attractive force between massive objects. Experiments and observations show that Einstein’s description of gravitation accounts for several effects that are unexplained by Newton’s law, such as minute anomalies in the orbits of Mercury and other planets. General relativity has developed into an essential tool in modern astrophysics.
It provides the foundation for the current understanding of black holes, regions of space where the gravitational effect is strong enough that even light cannot escape. Although general relativity is not the only relativistic theory of gravity, it is the simplest such theory that is consistent with the experimental data. Several physicists, including Einstein, searched for a theory that would reconcile Newton’s law of gravity and special relativity. Only Einstein’s theory proved to be consistent with experiments and observations.
Since everything in the elevator is falling together, no gravitational effect can be observed. Roughly speaking, the principle states that a person in a free-falling elevator cannot tell that they are in free fall. Most effects of gravity vanish in free fall, but effects that seem the same as those of gravity can be produced by an accelerated frame of reference. Objects are falling to the floor because the room is resting on the surface of the Earth and the objects are being pulled down by gravity. Objects are falling to the floor because the room is aboard a rocket in space, which is accelerating at 9. 2 and is far from any source of gravity. The objects are being pulled towards the floor by the same “inertial force” that presses the driver of an accelerating car into the back of his seat.