29. Mai 2011 · The Meaning of Relativity. Four lectures delivered at Princeton University, May, 1921. Credits. Andrew D. Hwang, updated for HTML+SVG by Laura Natal Rodrigues. Language.
Definition and basic properties. General relativity is a metric theory of gravitation. At its core are Einstein's equations, which describe the relation between the geometry of a four-dimensional pseudo-Riemannian manifold representing spacetime, and the energy–momentum contained in that spacetime. 
9. Juni 2021 · Proposed in 1916, Einstein’s general theory of relativity explained that gravity was a special force that existed because of the curvature of space-time itself. Space-time, according to this theory, is not flat. Thus, orbiting bodies travel in geodesics—the shortest distance between two points. This is the nearest thing to a straight line.
In physical theories prior to that of special relativity, mass and energy were viewed as distinct entities. Furthermore, the energy of a body at rest could be assigned an arbitrary value. In special relativity, however, the energy of a body at rest is determined to be mc 2.
9. Nov. 2023 · Special relativity revealed that the speed of light is a limit that can be approached but not reached by any material object. It is the origin of the most famous equation in science , E = m c 2 , which expresses the fact that mass and energy are the same physical entity and can be changed into each other.
10. Nov. 2023 · General relativity has been experimentally verified by observations of gravitational lenses, the orbit of the planet Mercury, the dilation of time in Earth’s gravitational field, and gravitational waves from merging black holes. (For a more detailed treatment of general relativity, see relativity: General relativity.)
Special relativity also produced the most famous equation ever written: E = mc2. It says that the energy ( E) associated with an object – an atom, a person or a whole galaxy – is equal to its total mass ( m) multiplied by the square of the speed of light (c). As the speed of light is about 300,000 km s -1, this means there is a whole lot of ...