S.N. Bose
and
His Discoveries
Overview
S.N. Bose (Satyendra Nath Bose) was an Indian mathematician and physicist who founded what is now known as Bose-Einstein statistics. Later, Einstein extended Bose’s ideas to atoms and predicted an exotic state of matter: Bose-Einstein condensate.
Though S.N. Bose did not receive the Nobel prize for his discovery, later, there were seven Nobel prizes awarded to discoveries in the field which started with Bose’s discovery.
Before getting into the details of his discovery, we should give a brief history of what was going on, in the world of physics and technology, at the end of 19th century.
It All Started With Building
More Efficient Light Bulbs
In the first half of the nineteenth century, in the UK, Michael Faraday demonstrated the concept of dynamo and electric motor. Scottish scientist James Maxwell predicted the existence of electromagnetic waves that travel at the speed of light. Heinrich Hertz, in Germany, experimentally verified the existence of electromagnetic waves. All those groundbreaking discoveries resulted in technological innovations like telegraphy, electric motor, and dynamo in the 2nd half of nineteenth century. Incandescent light bulb was one of the inventions in this series of innovations.
In 1880s, German companies tried to develop more efficient light bulbs than their American and British rivals. This required a full understanding of the relationship between the temperature of a body, the range of light colors a body emits and their light intensities.
For instance, consider putting an iron rod in a fire. What happens to it? As it becomes hot, it turns red. Then the color changes from red to orange, then yellow and finally a bluish white. The question physicists had was what the relationship between the temperature, the color of the light, and the intensity of radiation was. This field of study in physics is known as blackbody radiation.
Blackbody Radiation Graph
In 1887, the German Government founded the Physikalishch-Technische Reichsanstalt (PTR) in Berlin. The need to make a better light bulb was the driving force behind the PTR’s blackbody research program in the 1890s. This research ultimately resulted in the discovery of quantum and opening a new field in physics – Quantum Mechanics.
German physicists like Gustav Kirchhoff, Wilhelm Wien, Lummer built several equipment to study the problem of blackbody radiation. They carefully studied the relationship between a body’s temperature, wavelength of the light it emits and the light intensity. And they plotted their experimental data in a graph. Their graph was similar to the one below.
The graph illustrates the relationship between the temperature of a body and the spectrum of radiation it emits and the intensity.
At relatively low temperatures, the emitted radiation is mostly in the infra-red region. As the temperature increases, the maximum intensity shifts to shorter wavelengths, successively resulting in red, orange, yellow and finally blueish white light.
Planck's Equation
Max Planck, a professor of theoretical physics at Berlin University, was puzzled by their findings. In 1900, in order to explain the experimental results, as a desperate attempt, Planck heuristically arrived at an equation. But the derivation of his equation, based on classical Boltzmann’s statistics, was not satisfactory.
Though the equation perfectly matched with experimental data, Planck himself was not happy with it, as he could not derive logically based on classical statistics.
Bose's Quantum Statistics
In 1924, S.N. Bose, as a Reader in the physics department of Dhaka University, while preparing for a lecture to his students on Planck’s radiation equation, realized that the derivation was not adequate and sound. He questioned the basis of applying classical (Maxwell-Boltzmann) statistics which assumed that every particle was unique and distinguishable. Instead, Bose argued that light particles (photons) of a particular frequency must be indistinguishable.
Using this groundbreaking idea, he modified the derivation to arrive at Planck’s equation in a most coherent and elegant way, without Bose himself realizing that he founded a new field: Quantum Statistics.
Einstein’s Recognition
When Bose tried to publish his research finding in The Philosophical Magazine, it got rejected. Bose then sent his research paper to Albert Einstein. Einstein instantly recognized the physical importance of his great idea. Einstein not only translated Bose’s paper in German but also got it published in Zeitschrift für Physik.
The statistics that Bose discovered is now known as Bose-Einstein statistics.
The class of particles that obey Bose-Einstein statistics are now called Bosons, in Bose’s honor. For instance, photon, the light particle, is a Boson.
Einstein later adopted Bose’s idea and extended it to atoms to discover an exotic phenomenon: Bose-Einstein condensate.
References
- “Quantum Einstein, Bohr and the Great Debate about the nature of Reality” by Manjit Kumar
- Einstein His Life and Universe by Walter Isaacson
- https://www.famousscientists.org/s-n-bose/
“S. N. Bose.” Famous Scientists. famousscientists.org. 19 Oct. 2016. Web. 6/7/2023 <www.famousscientists.org/satyendra-nath-bose/>.