Why is the sea blue?
For half a century, since the discovery of Rayleigh scattering in 1871, the scientific world believed that the ocean simply reflected the blue sky. Returning from London on a steamboat in 1921, Sir CV Raman observed the ocean for a long time, leading him to question this hypothesis. Driven by this curiosity, he studied the molecular diffraction of light, which finally led him seven years later in February 1928 together with his colleague KS Krishnan to the discovery of the Raman effect.
Today, the Raman effect is widely used in our daily lives, especially to image objects ranging from a strand of DNA to your luggage at the airport. The curiosity that led Raman exactly a century ago to pull a Nicol prism out of the middle of an ocean and observe its color is the driving force behind what we call science. Every year, on February 28th, India celebrates National Science Day to mark the discovery of the Raman Effect and to underline the importance of science in our daily lives.
The theme of National Science Day 2022 is “Integrated Approach in Science and Technology for a Sustainable Future”. Today the world stands at a crossroads, with some using science for war and destruction and others using it for a sustainable future. The day reminds us of the incredible achievements of Indian scientists in the recent past and encourages us to carry on their legacy for a better tomorrow.
As the world rapidly made incredible scientific advances over the past century, India was not left behind, thanks to the incredible contributions of a few respected scientists among us. Here is a look back at some important discoveries made by famous Indian scientists of the 20th century.
Revolutionizing Wireless Communications – Sir Jagadish Chandra Bose
One day in November 1895, Lieutenant Governor Sir William McKenzie and others gathered at Calcutta City Hall for a scientific conference. But they expected a surprise. Sir Jagadish Chandra Bose, one of the first to champion the idea of wireless communications, conducted an experiment at the conference that many in attendance believed was a magic trick.
Bose sent out microwaves that penetrated three walls and activated the relays that fired a cannonball and rang a bell. This was perhaps the first experimental evidence for wireless communication through electromagnetic waves. Bose went on to invent a Mercury Coherer, a radio wave receiver later used by Marconi to transmit radio signals over a distance of 2000 miles.
Bose was one of the most talented scientists of his generation. He has been credited with numerous scientific discoveries in several fields, including scientifically proving that plants also feel pain.
Today, the technology developed by Bose powers all of our satellite communications, cell phones, television broadcasts and the Internet. We owe our modern lifestyle to Bose, who broke down the instrumental barriers of his time to find solutions.
The Boundless “Chandrasekhar Boundary” – Subrahmanyan Chandrasekhar
Out of 118 elements listed on the periodic table, only four came from the Big Bang during the formation of the universe. All other elements were created in nuclear reactions in large stars and in giant stellar explosions known as supernovae. Before 1930 there was no explanation as to how this happened.
In 1930, a 19-year-old Indian physicist traveled to England with his calculations that were to turn astrophysics upside down. The scientific theory popular at the time was that as a star burns up its fuel, it turns into a cold mass of ash. On the other hand, the young Indian scientist Subrahmanyan Chandrasekhar proposed that the larger stars could collapse under their own gravity and provided irrefutable mathematical evidence for his theory.
Chandrasekhar’s calculations were seminal evidence for the existence of what we now call black holes. However, at the time, the scientific community fiercely rejected his idea. The legendary astrophysicist Sir Arthur Stanley Eddington famously said that Chandrasekhar’s theory was a mathematical game and that mathematics could not explain the great physical realities.
Time proved Chandrasekhar right, and now we know that stars heavier than 1.4 times the mass of the Sun eventually collapse into supernovae, resulting in black holes, while lighter stars become white dwarfs. This weight limit is known as the Chandrasekhar limit, and for this discovery he was awarded the Nobel Prize in 1983.
Star classification using the ionization theory – Meghnad Saha
Not all scientists of the 20th century came from privileged families with a good education, some had to overcome poverty and discrimination in order to show their scientific brilliance. One of them was Dr. Meghnad Saha! Born in 1893 to a lowly poor family in a village near Dhaka, Saha later became a member of the Royal Society and chaired the 21st session of the Indian National Congress in 1934. He was even elected MP by Calcutta in 1952.
Among his academic awards is the English translation of the papers of Einstein-Minkowski, in which he explains the theory of relativity in German together with his classmate Satyendra Nath Bose. In the 1920s, while delving deeper into spectral studies of stars, he proposed the Saha ionization theory. His theory helped us understand that, in addition to their composition, temperature and pressure also affect the spectral behavior of stars. By combining quantum and statistical mechanics to explain the spectral classification of stars, Saha laid the foundation for a whole new branch of astrophysics called stellar spectroscopy!
The “God Particle” has an Indian surname – Satyendra Nath Bose
While General Relativity explains gravity, the Standard Model of Physics explains everything else in the known universe in terms of fundamental forces. An elementary particle called the “Higgs boson” confirms the Standard Model and explains the structure of the matter that makes up the entire universe. For this reason it is called the “God Particle”. While the particle is named after Peter Higgs, who proposed its existence in 1964, it belongs to a class of particles named after an Indian scientist, Satyendra Nath Bose.
All particles are classified as either bosons or fermions. Bosons, the particles that obey Bose-Einstein statistics, were conceived by Bose and developed in collaboration with the great Albert Einstein.
Bose is believed to have come up with the idea while explaining the theory of radiation to his students at Dhaka University. He recognized that existing theories do not explain the behavior of microscopic particles and developed a novel method to better explain it. He later explained the idea in a letter to Einstein, who immediately recognized its importance and sent Bose’s article for publication in a prestigious journal. Because of the attention the article received, Bose traveled to Europe and worked with great minds like Einstein and Marie Curie.
The Bhabha Scattering – Homi Jehangir Bhabha
We all remember Homi Jehangir Bhabha for his contributions to Indian atomic energy research. Bhabha is considered the father of Indian nuclear power and has made immense contributions to the field of nuclear physics throughout his career. But before moving into nuclear physics, he started out as a theoretical physicist and made a notable contribution.
Bhabha’s calculation determined electron-positron scattering, better known as Bhabha scattering, as early as 1935. He used this theory not only to understand the interaction of cosmic rays with the upper atmosphere, but also as an experimental confirmation of Albert Einstein’s theory of relativity. This work of his also led to groundbreaking advances in the field of nuclear physics.
Today, as we celebrate National Science Day, let us take a moment to reflect on the mammoth contributions of these and many other scientists on whose shoulders science in India continues to thrive.
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