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..

For more information about the topic Introduction to general relativity, read the full article at Wikipedia.org, or see the following related articles:

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

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