  Einstein's genius and penetrating physical intuition led to the general
theory of relativity, which incorporates gravity into the geometry of
spacetime. However, the theory of general relativity leads to perspectives
which go far beyond the vision of its creator. Many of these insights came to
light only after Einstein's death in 1955. These developments were due to a new
breed of relativists, like Penrose, Hawking and Geroch, who approached the
subject with a higher degree of mathematical sophistication than earlier
workers. Some of these insights were made possible because of work by Amal
Kumar Raychaudhuri (AKR) who derived an equation which turned out to be a key
ingredient in the singularity theorems of general relativity. This article
explains AKR's work in elementary terms.
