Short History
Einstein first mentions Bucchu's feasibility for the path of light for the Sun's gravitational field in his theory of general relativity. Subsequently, English scientist Arthur Edington (1882-1944) evaluated its authenticity with the help of the test (interested readers can see the Binstein-produced Einstein and Eddington television movie in 2008 for details). But Einstein did some more important work with Bichuchi in the path of light before his general relativity suggestion, where there is an indication of the first gravitational lensing.
If the incoming light from a remote light source is influenced by the gravitational field of a heavy object on its journey, that light rays can reach the observer on two different routes. As shown in the next figure - On the journey of the incoming light from the remote source S, the M objects reach the observer at two different ways, influenced by the gravitational field. As a result, O observant O can see two different images of the same object S.
Einstein first mentioned in his notebook the possibility of this special feature of gravitational lansing in 1912. At that time he discussed a lot about the idea of experimenting with the idea of astronomer Arvin Freandlich (Erwin Freundlich, 1885 - 1964) in Berlin. Einstein published some basic concepts and formulas for lancing in his notebook. A picture of his notebook was given below.
