Biography,  Science,  Uncategorized

Amal Kumar Raychaudhuri: The Legacy of an Indian Physicist.

You know what is one of the major problems with Science in India, especially after the british era?

We lack in scientific temper or that scientific environment among most of us. We failed to appreciate our own scientists who contributed immensely to science. Whereas the whole world admired their contribution, most of them remain a hidden figure in their own homeland.

Amal Kumar Raychaudhuri is such a name among them. Have you heard about him before? If you are/ were not a student of cosmology. Maximum chance is you haven’t heard about him.

But why is it so? Does only physics students know about Einstien or Stephen Hawking? No, right. They are loved by the entire world for their work and most importantly they got the respect from their own homeland.

You must be thinking what Amal Raychaudhuri had done?

Stephen Hawking admired Amal Kumar Raychaudhuri many times. In fact, Stephen Hawking in his Doctoral thesis ‘Properties of Expanding Universe’ used Amal Raychaudhuri’s findings to arrive at the solution.                                                                                                                                                                        Moreover, his findings helped immensely to find out the behavior of black holes and other aspects of cosmology. 

So what exactly were the findings of Prof. Amal Raychaudhuri?

In 1915 Albert Einstien amazed the world with his ‘General Theory of Relativity’ that transformed the understanding of nature of space and time and it also gave a new perspective of classical physics.                                         

General theory of Relativity

His theory proved that gravity is not a force rather it’s a manifestation of curved space and time. ‘General theory of relativity’ also showed the effect of gravity on light and time. 

Since then, it is one of the most successful theories which is universally accepted and can explain a plethora of physical phenomena like bending light, black holes, expanding universe and many more.

However, one area where ‘General theory of relativity’ seems to break down is in singularity.

What is a singularity?

A singularity is a point or region of infinite mass density at which space and time are infinitely distorted by gravitational forces and which is held to be the final state of matter falling into a black hole. 

Singularities were first proposed by Albert Einstein as a result of the theory of general relativity. He was quite worried about the appearances of singularities. He was looking for some way out of this.

But how does these singularities form?

A Supernova Remnant (SNR) is a diffuse, expanding nebula resulting from a spectacular explosion of a star in which it ejects most of it’s mass in a violently expanding cloud of debris. If the remnant is massive enough (heavier than few solar masses), then the remnant itself squeezes inward by gravity, forming a singularity, or black hole (one of the ways how black holes form).

Supernova Remnant

In this regard, Amal Kumar Raychaudhury has a great contribution as his equation (Raychaudhuri equation) helped immensely to explain space-time singularities and gravitational focusing property in cosmology. He addressed the fundamental question of singularity in most simple and general form with no reference to any symmetry and any specific property of space-time and energy distribution. 

His work later helped physicists all over the world (including Stephen Hawking) to explain other physical phenomena in cosmology in a simple manner. 

Amal Raychaudhuri published his famous equation in the year 1954 and the first mention of ‘Raychaudhuri equation’ appeared in a research paper published in 1965 by George F. R. Ellis and Stephen Hawking. In fact, this equation is the foundation of the famous Penrose-Hawking singularity theory in cosmology.

Instead of such contribution to the world of science, Amal Kumar Raychaudhuri (more commonly known as AKR) remain a hidden figure.                                              How was his life? What’s his story?

AKR was born in Barisal, now in Bangladesh, on 14 September 1923. He was just a child when the family migrated to Kolkata. His father was a school teacher in mathematics in Kolkata and AKR might have imbibed his love for mathematics from him.

 He had his early education in Tirthapati Institution and later completed matriculation from Hindu School. He did his graduation from Presidency College in 1942 followed by master’s degree from Calcutta University in 1944. It was right after this that AKR joined as a research fellow in the
Indian Association for the Cultivation of Science (IACS) to work in X-ray crystallography and then Ashutosh college, Calcutta as a lecturer in 1949. 

Later in 1952 he again joined IACS as research assistant. It was around that time he formulated the famous ‘Raychaudhuri equation’. 

In 1961 he joined the Presidency College, Kolkata as Professor of Physics. An account of him would be incomplete if it did not highlight his role as a teacher. He was a great teacher and a role model for his students. His popularity as a teacher could be guessed by a  quote his student, the late Narayan Rana, who dedicated the book Classical Mechanics (coauthored with P S Joag) with the words-

“to Professor Amal Kumar Raychaudhuri of Presidency College, Calcutta – Generations of Indian students owe their Classical Mechanics to you!’’

 AKR married Nomita Sen in 1958 and had two sons and two daughters. He used to lead a simple life. 

Till the end of life he was always busy in writing books, teaching and in his research work. His last paper published in the year 2004, just one year before his death. 

AKR died on 18th June 2005. Till his last day, he had a very positive outlook towards life, a strong sense of honesty and integrity.

The kind of scientific work he had done despite all the adverse and challenging situations that time is an inspiration for scientists all over the world. 

He was a living example who showed, a scientist’s biggest asset is his invincible curiosity and quest for self-learning.

It’s high time we appreciate our scientists and bring them to limelight so that they don’t remain a lesser known figure always.

There is a documentary on the great scientist made just before death. Click the link below-

A quote by Brian Greene worth remembering-


Have a curious week. Until next time.                                                                                                                                          – Joy


  1. Amal Raychaudhuri
  2. The story of an Indian physicist


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