Indian Scientists who changed the world
Shreya Pareek

Science is an important part of our everyday life, even more so than we notice. From our fancy gadgets to the technologies we can’t live without, from our humble light bulb to the space explorations, it is all a gift of science and technology.

I wonder what we would be doing if none of these things were invented? How often do we take out the time to think about those extraordinary minds who made life easier for us? Here is a series on Indian scientists whose path-breaking achievements led to the international progress of Science. In this issue, we start with the stalwart, Sir C V Raman.

Chandrasekhara Venkata Raman won the Nobel Prize in Physics for his pioneering work on the scattering of light. Born in Tiruchirapalli on November 7, 1888, he was the first Asian and first non-White to receive any Nobel Prize in the sciences.

The Blue Sky
It was Lord Rayleigh who first showed that the sky is blue because the blue light in the Sun's rays are scattered more that the red end of the rainbow spectrum. So when sunlight falls on the molecules such as nitrogen, carbon-dioxide or water vapour in the Earth's atmosphere, the light is scattered such that the sky appears blue, especially at angles away from the Sun. Here the different colours of light are simply scattered away at different angles, but the colours remain the same: blue light is scattered as blue light, red light as red, and so on.

Since the sky was blue, it was thought that the sea looks blue due to reflections of the sky. But when Raman was returning from England by ship and was fascinated by the intense blue colour of the Mediateranean sea, he became curious about how the sea could be more blue than the sky. He came back to the University of Calcutta where he was working and studied this problem. He showed that it was the property of water itself that caused the blue light to scatter more and had nothing to do with the colour of the sky.

The Raman Effect
Raman also made a detailed study of these properties of water and other liquids. He discovered that, when light traverses a transparent material, some of the scattered light is the same colour as the original one but there is also another colour, with a lower frequency. The new frequency depended on the molecules contained in the liquid. This phenomenon is now called the Raman scattering and is the result of the Raman effect. This fantastic discovery made on 28 Feb, 1928, was announced in a press report the next day, for which reason February 28th is celebrated as National Science Day in India. Curiosity about the world around him led to the Nobel prize in 1930.

Raman Scanner
Raman also invented an instrument called the spectrograph that could determine the frequency of light falling on it. The Raman effect has numerous uses in science and technology. Since the emitted frequency of light depends on the substance it passes through, it can be used to identify the substance. The Raman Scanner can therefore be used to see if people are carrying any banned substances, without opening the baggage and examining the contents. 

Other Work
Raman also worked on the acoustics of musical instruments. He was the first to investigate the harmonic nature of the sound of the Indian drums such as the tabla and the mridangam. He also had a fabulous gem collection which he used in his studies on light and crystals. These can be seen even today at the Raman Research Institute in Bangalore.

Raman on War and Peace
He died of natural causes on 21 November 1970. Till the end he was passionate about the science journals that he had helped to grow, which were essential for the enhancement of science and scientific temper. He was horrified at the development of the atom bomb. “The world, which is so keen on using the achievements of physics for the purpose of mass destruction, would be better” employed for the peaceful settlement of conflicts, he said.