When a beam of light passes near a massive object, such as a galaxy or a black hole, its path can be bent due to the gravitational influence of the object. This phenomenon is known as gravitational lensing. Gravitational lensing can occur in two main forms: strong lensing and weak lensing.
In the case of strong gravitational lensing, where the mass distribution of the object is significant, the light beam can be significantly deflected and distorted. The gravitational field of the massive object acts as a lens, bending the path of the light and causing it to follow a curved trajectory. If the alignment is precise, the light can be focused or even form multiple images of the source object. This effect can produce stunning visual effects, such as the appearance of rings or arcs of light around the massive object.
In the case of weak gravitational lensing, where the mass distribution is less pronounced, the deflection of light is subtler. It results in a slight distortion or stretching of the background objects rather than producing multiple distinct images.
Gravitational lensing has been observed and studied by astronomers, providing valuable insights into the distribution of mass in the universe, the nature of dark matter, and the properties of distant galaxies and black holes. It offers a unique way to indirectly study objects that are otherwise difficult to observe directly.
It's important to note that while gravitational lensing can bend light, it does not fundamentally change its nature. The deflected light still behaves as a wave or a particle, depending on how it is measured or observed.