Light bends or curves in space due to the effect of gravity, as described by Einstein's theory of general relativity. According to this theory, massive objects, such as stars, planets, or black holes, create a gravitational field that curves the fabric of spacetime.
The curvature of spacetime caused by a massive object affects the path of light passing through it. When light travels near a massive object, it follows a curved trajectory instead of a straight line. This bending of light is often referred to as gravitational lensing.
Gravitational lensing occurs because light always travels along the shortest path in spacetime, which is known as a geodesic. In the presence of a massive object, the geodesic is no longer a straight line but a curved path due to the spacetime curvature. Therefore, when light passes close to a massive object, its path bends, following the curvature of spacetime.
The amount of bending depends on the mass and proximity of the object. A more massive object or a closer approach will cause a greater curvature and a more significant deflection of light. This effect can be observed and measured during astronomical observations, where light from distant objects is deflected by massive celestial bodies in its path.
One famous example of gravitational lensing is the observation of distant galaxies behind massive galaxy clusters. The gravitational pull of the cluster bends the path of light from the distant galaxies, resulting in distorted and magnified images. This phenomenon provides valuable insights into the distribution of matter and the properties of gravity on a cosmic scale.
In summary, light bends in space due to the curvature of spacetime caused by the presence of massive objects, as described by Einstein's general theory of relativity.