Final answer:
Observed gravitational lensing behaves like a converging lens due to the warping of spacetime around massive objects like galaxies and dark matter clusters. It confirms general relativity and aids in studying the distribution of dark matter.
Step-by-step explanation:
Observed gravitational lensing corresponds to a converging lens. This phenomenon occurs because mass, including both visible galaxies and dark matter, warps the surrounding spacetime as described by Albert Einstein's theory of general relativity. This curvature causes light to bend toward the mass, similar to how a glass lens bends light to a focal point. On astronomical scales, this effect can manifest when the light from a distant galaxy passes close by another massive object on its way to our telescopes on Earth. The result is that the massive object acts much like a converging lens, creating multiple images or arcs of the background galaxy.
Gravitational lensing has been observed on several occasions and is considered a significant verification of general relativity. Furthermore, it provides insights into the amount and distribution of dark matter in galaxy clusters, as it allows astronomers to calculate detailed maps of mass distribution from the observed lensing effects.
The red shift observed in gravitationally lensed images provides additional evidence that the light has not simply 'tired' by traveling through space but is affected by the gravitational influence of intervening mass. Consistent red shifts among multiple images of a lensed object confirm that they are indeed multiple views of the same source, not different objects.