> [!infobox] <s class="aside-in"><em>mentioned in 11 topics, 2 evergreens, 2 sources</em></s> #### <s class="topic-title">[[general relativity]]</s> > [!wikipedia] [general relativity](https://en.wikipedia.org/wiki/General%20relativity) > > General relativity, also known as the general theory of relativity and [[Einstein]]'s theory of [[gravity]], is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time or four-dimensional spacetime. In particular, the curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by the Einstein field equations, a system of second order partial differential equations. > > [[Newton]]'s law of universal gravitation, which describes classical gravity, can be seen as a prediction of general relativity for the almost flat space-time geometry around stationary mass distributions. Some predictions of general relativity, however, are beyond [[Newton]]'s law of universal gravitation in classical physics. These predictions concern the passage of time, the geometry of space, the motion of bodies in free fall, and the propagation of light, and include gravitational time dilation, gravitational lensing, the gravitational redshift of light, the Shapiro time delay and [[singularities]]/[[black holes]]. So far all tests of general relativity have been shown to be in agreement with the theory. The time dependent solutions of general relativity enable us to talk about the history of the universe and have provided the modern [[framework]] for cosmology, thus leading to the discovery of [[the Big Bang]] and [[Cosmic Microwave Background radiation]]. Despite the introduction of a number of alternative theories, general relativity continues to be the simplest theory consistent with experimental data. Reconciliation of general relativity with the laws of [[quantum physics]] remains a problem however, as there is a lack of a self-consistent theory of quantum gravity; and how gravity can be unified with the three non-gravitational forces—strong, weak, and electromagnetic forces. > > [[Einstein]]'s theory has astrophysical implications, including the prediction of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape from them. [[Black holes]] are the end-state for massive stars. Microquasars and active galactic nuclei are believed to be stellar black holes and supermassive black holes. It also predicts gravitational lensing, where the bending of light results in multiple images of the same distant astronomical phenomenon. Other predictions include the existence of gravitational waves, which have been observed directly by the physics collaboration LIGO and other observatories. In addition, general relativity has provided the base of cosmological models of an expanding universe. > > Widely acknowledged as a theory of extraordinary beauty, general relativity has often been described as the most beautiful of all existing physical theories. ##### ^dataviews > [!dataview]+ Related unlinked notes > > - [[A light year is not a year when you are travelling near the speed of light]] > - [[Everybody on earth is just barely experiencing time at the same rate]] > [!dataview]- Other unlinked mentions > > - [[video - Black Hole Mergers and Multi-Messenger Astronomy]] > - [[video - The Sixth Dimension]] > - [[topics]] > - [[classical mechanics]] > - [[cosmological constant]] > - [[dark energy]] > - [[dark matter]] > - [[expanding universe]] > - [[gravitational singularity]] > - [[special relativity]] > - [[time dilation]]