What is gravitational lensing?

Gravitational lensing is a phenomenon that occurs when the gravitational field of a massive object, such as a galaxy or a cluster of galaxies, bends the light coming from a more distant object, such as a galaxy or a quasar, that lies behind it in the observer's line of sight. This bending of light is a prediction of Einstein's General Theory of Relativity, which describes how mass can warp the fabric of spacetime.

As light travels through the gravitational field of the massive object, its path is altered, leading to the appearance of distorted, magnified, or even multiple images of the distant object. This effect allows astronomers to study objects that are otherwise too faint or distant to observe directly. Gravitational lensing has provided valuable insights into the distribution of dark matter, galaxy formation, and the expansion of the universe.

The other choices describe different processes that involve light but do not pertain to the specific phenomenon of gravitational lensing caused by gravity's influence on light.