"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."
The theory of gravity developed by Einstein, which describes the curvature of spacetime due to the presence of matter and energy.
Special Relativity: Special relativity is a theory developed by Albert Einstein in 1905 that explains the laws of physics for objects moving at a constant velocity relative to each other. It is a precursor to general relativity and is necessary to understand the ideas of general relativity.
Equivalence Principle: The equivalence principle is a fundamental concept in general relativity that states that the effects of gravity are equivalent to those of acceleration. It is a key principle that underlies the entire theory.
Metrics and Coordinate Systems: Metrics are mathematical constructs that define the geometry of space-time. They are used to measure distances and durations and can be used to calculate the effects of gravity in general relativity. Coordinate systems are used to describe the location of events.
Geodesics and Curvature: Geodesics are the paths that objects in space-time follow when they are not acted upon by any external forces. The curvature of space-time is determined by the distribution of matter and energy in the universe and is one of the central ideas in general relativity.
Einstein Field Equations: The Einstein field equations are a set of ten partial differential equations that describe the behavior of gravity in terms of the curvature of space-time. They are the foundation of general relativity and are used to calculate the gravitational fields of objects.
Black Holes: Black holes are objects in space that have such strong gravitational fields that nothing, not even light, can escape. They are a consequence of the curvature of space-time and the mass and energy contained within it.
Gravitational Waves: Gravitational waves are ripples in the fabric of space-time caused by the acceleration of masses. They were first predicted by Einstein's theory of general relativity and were finally detected in 2015. They represent an entirely new way to explore and understand the universe.
Cosmology: Cosmology is the study of the origin, evolution, and structure of the universe. General relativity is used to describe the large-scale structure of the universe, including the formation of galaxies and the expansion of the universe.
Experimental Tests of General Relativity: General relativity has been tested and verified through numerous experiments and observations, including the bending of starlight during a total solar eclipse, the precession of the orbit of mercury, and the detection of gravitational waves.
Quantum Gravity: Quantum gravity is the field of study that attempts to reconcile general relativity with quantum mechanics. It is a very active area of research and represents one of the major challenges in modern physics.
Continuous waves: These are gravitational waves that are continuously emitted as two massive objects orbit each other.
Burst waves: These waves are generated by violent astrophysical events, such as supernovae, which produce a sudden burst of gravitational radiation.
Inspiral waves: These waves occur as two bodies gradually come closer together and eventually merge, emitting gravitational radiation in the process.
Ringdown waves: These waves happen when a black hole forms after a merger and emits gravitational radiation as it settles down to a stable state.
Stochastic waves: These are random gravitational waves that arise from the cumulative effect of many astrophysical events, such as mergers of smaller black holes or neutron stars.
Polarization waves: These waves are characterized by the direction of oscillation of the gravitational wave. Gravitational radiation can have two polarizations, similar to the way light can be polarized.
Primordial waves: These gravitational waves are thought to have been generated in the earliest moments of the universe, just fractions of a second after the Big Bang, and may provide a window into the universe's infancy.
Cosmological waves: These waves are produced by large-scale structures in the universe, such as expanding bubbles or cosmic string networks, and could potentially be detected with future gravitational wave detectors.
Superradiant waves: These are waves that are emitted when a spinning black hole rotates at a rate close to its maximum allowed speed, and can extract energy and angular momentum from the black hole's rotational energy.
"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."
"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."
"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."
"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."
"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."
"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."
"General relativity provides a unified description of gravity as a geometric property of space and time or four-dimensional spacetime."
"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."
"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."