"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 that describes the behavior of gravity in terms of the curvature of spacetime caused by the presence of matter and energy.
Special relativity: Understanding the foundations of relativity, including the principle of relativity, the speed of light as a constant, time dilation, length contraction, and the equivalence of mass and energy.
Riemannian geometry: Introducing the mathematics of curved spacetime and how to define geometric quantities in this context, such as metric tensors, Christoffel symbols, curvature tensors, and geodesics.
Einstein field equations: Deriving and understanding the most fundamental equations of general relativity, which relate the curvature of spacetime to the distribution of matter and energy through the stress-energy tensor.
Schwarzschild solution: Studying the first exact solution of the Einstein field equations, which describes the spacetime geometry around a non-rotating, spherically symmetric mass and leads to the prediction of black holes.
Cosmology: Understanding how general relativity has revolutionized our understanding of the universe as a whole, such as the Big Bang theory, cosmic microwave background radiation, dark matter, and dark energy.
Gravitational waves: Studying the detection and phenomena associated with gravitational waves, including their generation by astrophysical sources, their propagation through spacetime, and their detection using large interferometers.
Black holes: Exploring the properties and behavior of black holes, including their formation, event horizons, singularities, and the laws of black hole thermodynamics.
Quantum gravity: Investigating the intersection of general relativity with quantum mechanics, and how various approaches such as loop quantum gravity, string theory, and M-theory attempt to reconcile these apparently incompatible theories.
Alternative theories of gravity: Considering proposed modifications or extensions of general relativity that modify its predictions in certain regimes, such as scalar-tensor theories, f(R) gravity, or braneworld scenarios.
Experimental tests of general relativity: Examining the many ways that general relativity has been tested and confirmed through experimental observations and measurements, such as the perihelion precession of Mercury, gravitational lensing, and the Shapiro time delay.
Classical general relativity: The classical theory of general relativity is based on Einstein's equations of gravity, which relate the curvature of space-time to the distribution of matter and energy.
Quantum gravity: Quantum gravity is a theoretical framework that aims to unify general relativity with quantum mechanics. It explores the possibility of describing the force of gravity in terms of particles, known as gravitons.
Cosmology: Cosmology is the study of the origin, structure, and evolution of the universe. General relativity plays a critical role in the field of cosmology, as it provides a theoretical framework for understanding the large-scale structure of the universe and the evolution of galaxies.
Black holes: General relativity predicts the existence of black holes, which are objects with such a strong gravitational field that nothing, not even light, can escape from them. The study of black holes is an important area of research within the field of general relativity.
Gravitational waves: General relativity predicts the existence of gravitational waves, which are ripples in the fabric of space-time caused by the acceleration of massive objects. The study of gravitational waves is a rapidly growing field within the broader field of general relativity.
"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."