What happens to spacetime in the presence of mass and energy according to general relativity?

In the framework of general relativity, mass and energy have a profound effect on the fabric of spacetime. Specifically, they cause spacetime to bend and curve. This distortion is a fundamental aspect of how gravity operates within this theory. Instead of viewing gravity as a force acting at a distance, general relativity describes it as the result of the curvature of spacetime caused by the presence of mass.

When a massive object, such as a planet or star, is situated in spacetime, it warps the surrounding spacetime structure, leading to what can be imagined as a "dent" in the fabric. This curvature influences the motion of other objects and light, which tend to follow the curved paths created by the mass. Therefore, the trajectories of moving objects change based on the geometry of spacetime molded by mass and energy, leading to what we perceive as gravitational attraction.

This understanding is pivotal in exploring various phenomena in the universe, such as the orbits of planets, the bending of light around massive objects (gravitational lensing), and the characteristics of black holes, which themselves are regions of extreme curvature in spacetime.