General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1916.
It unifies Einstein's earlier special relativity with Sir Isaac Newton's law of universal gravitation.
This is done with the insight that gravitation is not due to a force but rather is a manifestation of curved space and time.
In general relativity, spacetime is non-Euclidean, or curved.
The need for curvature arises from the equivalence principle and a child's simple question: "What keeps the people on the other side of the world from falling off?".
In other words, should not the inertial paths on the other side of the Earth take objects away from the planet? Instead, all free-fall trajectories in the vicinity of a massive object will draw objects towards it.
Gravitation Gravity is a force of attraction that acts between bodies that have mass. Gravity is the reason for the very existence of the earth, the sun and ... >
read more
Spacetime In physics, spacetime is a model that combines 3-D space and 1-D time into a single construct called the space-time continuum (the 4th ... >
read more
General relativity General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. It unifies special relativity and Sir Isaac ... >
read more
Euclidean geometry Euclidean geometry is a mathematical well-known system attributed to the Greek mathematician Euclid of Alexandria. Euclid's text Elements was the ... >
read more
Special relativity Special relativity inter-relates space and time in such a way that the speed of light is constant, and the theory leads to situations where two ... >
read more
Physics Physics is the science of matter and its motion—the science that deals with concepts such as force, energy, mass, and charge. As an ... >
read more
Gravitational wave In physics, in terms of a metric theory of gravitation, a gravitational wave is a fluctuation in the curvature of space-time which propagates as a ... >
read more
Hypothesis A hypothesis is a proposed explanation for a phenomenon. A scientific hypothesis must be testable and based on previous observations or extensions of ... >
read more
Black hole A black hole is a concentration of mass great enough that the force of gravity prevents anything from escaping it except through quantum tunnelling ... >
read more
Physical cosmology Physical cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental ... >
read more