John wheeler: Time and space tell how matter moves; Matter tells space-time how to bend. Time and space tell matter how to move, and matter tells time and space how to bend. )

General relativity is a theory about gravity, and its mathematical basis is differential geometry, based on the principle of generalized covariance and strong equivalence.

Basic viewpoint: Time and space exist as a whole, space-time is curved, and the distribution of matter (all matter with energy, including solid particles, radiation and dark matter with dark energy) can interact with space-time.

Mathematical language: Space-time is a four-dimensional simply connected manifold M with Lorenz sign difference metric g_ab, whose properties are described by Ritchie tensor R_ab, curvature scalar R and other geometric quantities, and the distribution state of matter is described by dynamic tensor T_ab. The core of light image is Einstein's field equation: R_ab- 1/2Rg_ab=kT_ab, which establishes the relationship between time and space and matter.

The weak field approximation with wide phase is special relativity, and the low speed approximation is the law of universal gravitation.