Britannica Sources used in this answer

How does mass and energy curve space-time in general relativity?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

gravitational lens — gravity A galactic cluster, about five billion light-years away, produces a tremendous gravitational field that “bends” light around it. This lens produces multiple copies of a blue galaxy about twice as distant. Four images are visible in a circle surrounding the lens; a fifth is visible near the center of the picture, which was taken by the Hubble Space Telescope.

In general relativity, gravity is not a force, but a consequence of the geometric curvature of space-time. Einstein’s theory posits that space-time is a dynamic entity that responds to the presence of matter and energy.12

The relationship between the distribution of mass-energy and the geometry of space-time is defined by the Einstein field equations. These differential equations dictate that matter and energy tell space-time how to curve, while the resulting curvature tells matter how to move.123

To visualize this, one can imagine space-time as a flexible sheet. In the absence of massive objects, the sheet is flat, and objects travel in straight lines. However, a massive body creates a depression in this sheet, curving the surrounding space-time. Objects moving near this mass follow the shortest natural paths, known as geodesics, which appear as curved trajectories or orbits due to the underlying geometry of the space-time they traverse.12