After a short span of publishing of General relativity, German physicist and astronomer Karl Schwarzschild in 1916 published the first exact solution to Einstein’s Field Equations. This was a remarkable achievement as Einstein’s himself found only an approximate solution. The solutions predicated a region in the universe where space-time is so curved that even light cannot escape which later popularised as Black Hole.

With the advent, the Einstein’s new theory of gravity, British physicist and astronomer Sir Arthur Eddington got interested in the theory and was thinking of finding a way to verify the theory. Around 1919 he thought of an idea as according to General Relativity light can bend around massive objects and Eddington's idea is to exploit this. In 1919 a solar eclipse is going to occur and its shadow zone lie from Brazil to north-western Africa two expedition teams got off one to the coast of Brazil and the other to North-Western Africa and the plan is to photograph the position of stars in Hyades, cluster in the constellation of Taurus which appear near to the sun and compare the image with the image when the sun is not in the path. A deviation is seen when images were compared giving a clear verification of Einstein's theory of General Relativity.

The 1960s was a golden decade in astronomy with the 1963 discovery of Quasars, astrophysicists are discovering new objects. Then comes the Roger Penrose pathbreaking 1965 paper titled "Gravitational Collapse and Spacetime Singularities". Check out this paper(only for interested and mathematically matured readers ).In this paper Roger Penrose proved that gravitational collapse of the star also created a singularity or more properly called as Event Horizon, which is basically a boundary in space-time which divide the event that was, is, will be observed by an observer and the events that can’t be observed by any means to the observer.