Gravitational lensing is a phenomenon that occurs due to the bending of light by gravitational fields. It is indeed related to Albert Einstein's theory of general relativity rather than Newtonian mechanics.
According to general relativity, mass and energy curve the fabric of spacetime, creating what we perceive as gravity. When light passes through a region with a strong gravitational field, such as near a massive object, its path gets bent due to the curvature of spacetime. This bending of light is the basis of gravitational lensing.
There are two main types of gravitational lensing: strong lensing and weak lensing.
Strong lensing: This occurs when a massive object, such as a galaxy or a cluster of galaxies, acts as a powerful gravitational lens. The gravitational field of the object causes light passing through its vicinity to be significantly distorted, leading to the formation of multiple, magnified, or distorted images of a background light source. These lensed images can sometimes appear as arcs or even complete rings, known as Einstein rings.
Weak lensing: Weak lensing refers to the subtle distortion of light caused by the gravitational influence of less massive objects, such as individual galaxies or dark matter. While the distortions in weak lensing are small and more challenging to detect, statistical analysis of large numbers of galaxies can reveal the gravitational effects, allowing astronomers to study the distribution of dark matter in the universe and gain insights into cosmology.
Gravitational lensing is a remarkable confirmation of Einstein's theory of general relativity, which predicts the bending of light in the presence of gravity. It has been observed and studied extensively in various astronomical contexts, providing valuable insights into the nature of gravity, the distribution of matter in the universe, and the properties of light itself.