Satyendra Nath Bose

While presenting a lecture[22] at the University of Dhaka on the theory of radiation and the ultraviolet catastrophe, Bose intended to show his students that the contemporary theory was inadequate, because it predicted results not in accordance with experimental results.

In the process of describing this discrepancy, Bose for the first time took the position that the Maxwell–Boltzmann distribution would not be true for microscopic particles, where fluctuations due to Heisenberg's uncertainty principle will be significant. Thus he stressed the probability of finding particles in the phase space, each state having volume h³, and discarding the distinct position and momentum of the particles.

Bose adapted this lecture into a short article called "Planck's Law and the Hypothesis of Light Quanta" and sent it to Albert Einstein with the following letter:[23]

Respected Sir, I have ventured to send you the accompanying article for your perusal and opinion. I am anxious to know what you think of it. You will see that I have tried to deduce the coefficient 8π ν²/c³ in Planck's Law independent of classical electrodynamics, only assuming that the ultimate elementary region in the phase-space has the content h³. I do not know sufficient German to translate the paper. If you think the paper worth publication I shall be grateful if you arrange for its publication in Zeitschrift für Physik. Though a complete stranger to you, I do not feel any hesitation in making such a request. Because we are all your pupils though profiting only by your teachings through your writings. I do not know whether you still remember that somebody from Calcutta asked your permission to translate your papers on Relativity in English. You acceded to the request. The book has since been published. I was the one who translated your paper on Generalised Relativity.

Einstein agreed with him, translated Bose's papers "Planck's Law and Hypothesis of Light Quanta" into German, and had it published in Zeitschrift für Physik under Bose's name, in 1924.[24]

The reason Bose's interpretation produced accurate results was that since photons are indistinguishable from each other, one cannot treat any two photons having equal energy as being two distinct identifiable photons. By analogy, if in an alternate universe coins were to behave like photons and other bosons, the probability of producing two heads would indeed be one-third (tail-head = head-tail).

Bose's interpretation is now called Bose–Einstein statistics. This result derived by Bose laid the foundation of quantum statistics, and especially the revolutionary new philosophical conception of the indistinguishability of particles, as acknowledged by Einstein and Dirac.[24] When Einstein met Bose face-to-face, he asked him whether he had been aware that he had invented a new type of statistics, and he very candidly said that no, he wasn't that familiar with Boltzmann's statistics and didn't realize that he was doing the calculations differently. He was equally candid with anyone who asked.

Standard Model of particle physics
Elementary particles of the Standard Model
Background Particle physics Standard Model Quantum field theory Gauge theory Spontaneous symmetry breaking Higgs mechanism
Constituents Electroweak interaction Quantum chromodynamics CKM matrix Standard Model mathematics
Limitations Strong CP problem Hierarchy problem Neutrino oscillations Physics beyond the Standard Model
Scientists Rutherford · Thomson · Chadwick · Bose · Sudarshan · Koshiba · Davis Jr. · Anderson · Fermi · Dirac · Feynman · Rubbia · Gell-Mann · Kendall · Taylor · Friedman · Powell · P. W. Anderson · Glashow · Iliopoulos · Maiani · Meer · Cowan · Nambu · Chamberlain · Cabibbo · Schwartz · Perl · Majorana · Weinberg · Lee · Ward · Salam · Kobayashi · Maskawa · Yang · Yukawa · 't Hooft · Veltman · Gross · Politzer · Wilczek · Cronin · Fitch · Vleck · Higgs · Englert · Brout · Hagen · Guralnik  · Kibble  · Ting · Richter

Velocity-distribution data of a gas of rubidium atoms, confirming the discovery of a new phase of matter, the Bose–Einstein condensate.[25] Left: just before the appearance of a Bose–Einstein condensate. Center: just after the appearance of the condensate. Right: after further evaporation, leaving a sample of nearly pure condensate.

Einstein also did not at first realize how radical Bose's departure was, and in his first paper after Bose, he was guided, like Bose, by the fact that the new method gave the right answer. But after Einstein's second paper using Bose's method in which Einstein predicted the Bose–Einstein condensate (pictured left), he started to realize just how radical it was, and he compared it to wave/particle duality, saying that some particles didn't behave exactly like particles. Bose had already submitted his article to the British Journal Philosophical Magazine, which rejected it, before he sent it to Einstein. It is not known why it was rejected.[26]

Einstein adopted the idea and extended it to atoms. This led to the prediction of the existence of phenomena which became known as Bose–Einstein condensate, a dense collection of bosons (which are particles with integer spin, named after Bose), which was demonstrated to exist by experiment in 1995.

Bose at Dhaka University in the 1930s

After his stay in Europe, Bose returned to Dhaka in 1926. He did not have a doctorate, and so ordinarily, under the prevailing regulations, he would not be qualified for the post of Professor he applied for, but Einstein recommended him. He was then made Head of the Department of Physics at Dhaka University. He continued guiding and teaching at Dhaka University.

Bose designed equipment himself for an X-ray crystallography laboratory. He set up laboratories and libraries to make the department a center of research in X-ray spectroscopy, X-ray diffraction, magnetic properties of matter, optical spectroscopy, wireless, and unified field theories. He also published an equation of state for real gases with Meghnad Saha. He was also the Dean of the Faculty of Science at Dhaka University until 1945.

When the partition of India became imminent (1947), he returned to Calcutta (now known as Kolkata) and taught there until 1956. He insisted every student design his own equipment using local materials and local technicians. He was made professor emeritus on his retirement.[19][27][6] He then became Vice-Chancellor of Visva-Bharati University in Santiniketan. He returned to the University of Calcutta to continue research in nuclear physics and complete earlier works in organic chemistry. In subsequent years, he worked in applied research such as extraction of helium in hot springs of Bakreshwar.[28]

Apart from physics, he did some research in biotechnology and literature (Bengali and English). He made deep studies in chemistry, geology, zoology, anthropology, engineering and other sciences. Being Bengali, he devoted a lot of time to promoting Bengali as a teaching language, translating scientific papers into it, and promoting the development of the region.[20][29][5]

S.N. Bose was nominated by K. Banerji (1956), D.S. Kothari (1959), S.N. Bagchi (1962) and A.K. Dutta (1962) for the Nobel Prize in Physics, for his contribution to Bose–Einstein statistics and the unified field theory. For instance, Kedareswar Banerjee, head of the Physics Department, University of Allahabad, in a letter of 12 January 1956 wrote to the Nobel Committee as follows: “(1). He (Bose) made very outstanding contributions to Physics by developing the statistics known after his name as Bose statistics. In recent years this statistics is found to be of profound importance in the classifications of fundamental particles and has contributed immensely in the development of nuclear physics. (2). During the period from 1953 to date he has made a number of highly interesting contributions of far-reaching consequences on the subject of Einstein’s Unitary Field Theory.” Bose's work was evaluated by an expert of the Nobel Committee, Oskar Klein, who did not see his work worthy of a Nobel Prize.[32][33][34]