Meghnad Saha
Encyclopedia
Meghnad Saha FRS (6 October 1893 – 16 February 1956) was an India
n astrophysicist best known for his development of the Saha equation
, used to describe chemical and physical conditions in stars.
(in present Bangladesh
). The youngest of the five sons of Jagannath Saha and Bhubaneswari Debi, Meghnad belonged to a poor family and struggled to rise in life. His father was reluctant to allow him to undergo higher education; he wanted him to assist him in shopkeeping. With some persuasion from his eldest son Jayant and Meghnad's primary school teachers, he relented, and Meghnad went to the neighbouring village to live there and attend an English-medium school. Here he was lucky in that one Mr. Ananta Kumar Das, a medical practitioner, took interest in Meghnad and offered him free boarding and lodging. In 1905, he joined the Dhaka Collegiate School
. Here he not only received a free studentship, but also a stipend. However he lost both his free studentship and stipend when he participated in a boycott against the then British Governor of Bengal Sir Bampfylde Fuller when he came on a visit to Dacca. He managed to pull through by joining the Kishorilal Jubilee School where he again received a free studentship and a stipend. Around this time Saha joined the Bible classes run by the Dacca Baptist Society. In a test that was conducted, Saha stood first and won a handsome prize of Rs.100/- plus a beautifully bound copy of the Bible
. In 1909 Saha passed the Collegiate entrance exam, standing first among the students from East Bengal, with highest marks in Mathematics, English, Sanskrit and Bengali. This got him entry into the Intermediate Dhaka College
, where he spent two years studying Intermediate. During this time he also took private lessons in German
which later was to stand him in good stead.
In 1911 he ranked third in the ISC exam. In the same year Saha came to Calcutta
and joined the Presidency College
to study for the B.Sc. degree in Applied Mathematics
. Presidency College by then had spawned numerous luminaries, and Saha found himself surrounded by many: Satyendra Nath Bose
, Jnan Ghosh, N.R. Sen, and J. N. Mukherjee were his classmates, P.C. Mahalanobis was one year his senior, N. R. Dhar was senior by two years, while Netaji Subhash Chandra Bose was one year his junior. His teachers included Jagadish Chandra Bose in physics, Prafulla Chandra Roy
in chemistry, D.N. Mallik and C. E. Cullis in mathematics. After B.Sc. came M.Sc. and once again S.N. Bose was his classmate. In M.Sc. and B.Sc. Saha secured the second rank, while Bose stood first, while in the M.sc. exam both stood first, Bose in Pure Mathematics and Saha in Applied Mathematics.
While in college during 1913 through 1915, Meghnad got involved with Anushilan Samiti
to take part in freedom fighting movement. Bagha Jatin
, a famous freedom fighter, was used to visit his hostel for building student organization., Saha flirted a bit with the idea of joining hands with revolutionaries in their fight against the British. However he soon gave up on the idea, his goal was to get a job, earn money and support his family. After college he tried to enter the Indian Finance Service, but he was denied permission to appear in the exam as he was suspected of having contacts with revolutionaries; besides, there was also the boycott he had participated in as a school student. In order to procure some income, he started giving private tutions. It was around this time that Sir Ashutosh Mukherjee
became the Vice Chancellor of Calcutta University
, and he opened a new College of Science for post-graduate studies and research - this was made possible because of the magnificent donations of two eminent lawyers of Calcutta, Tarak Nath Palit and Rash Behari Ghose. He offered lecturerships to both Saha and Bose in the Department of Mathematics in this college but because they could not get along with Dr. Ganesh Prasad
, the professor, he transferred them to the Physics Department where C.V. Raman had been appointed the Palit Professor. In later life he was close to Amiya Charan Banerjee
, a renowned mathematician at Allahabad University.
. Saha got deeply interested in the relativity theory. He, jointly with S. N. Bose, prepared an English translation of Einstein's papers, later published in the form of a book by the University of Calcutta
. The study of relativity led Saha to some investigations in electromagnetic theory and his first original paper entitled On Maxwell's stresses appeared in the Philosophical Magazine in 1917 and quickly followed it up with several more in the next couple of years. This was followed by papers on the dynamics of the electron. He derived, on the basis of the Special theory of Relativity
, the Liénard–Wiechert potential due to a point-charge. During these years he also worked on radiation pressure, and in 1918 (with S. Chakravorti) he published in the Journal of the Royal Asiatic Society of Bengal (Calcutta) a paper on the measurement of the pressure of light using a resonance method. These were substantial enough for the Calcutta University to award him the D.Sc. degree in 1918. In between, Saha got married to Radharani (he had believed that a celibate life was most fit for him until he read The Cloister and the Hearth
, which resolved him to marry). At this point of time he became interested in the phenomenon of selective radiation pressure. The question that piqued his curiosity was that how come a heavier element like Calcium
is present up to a greater height compared to a lighter element like Hydrogen
, apparently defying gravity. He had read in Agnes Clerke's book about the ‘hypothetical levitative force’ which apparently acted on atoms of some elements only, e.g. calcium. Several models had already been proposed to explain this anomaly, all of them banking on the possibility of a sharp decrease of density with increase in height that might negate the effect of increased weight of the element. One such model suggested by Schwarzschild
predicted that at a height of around 3500 km, there would be only one atom in a billion cubic metres. However the flash spectra showed that the abundance of atoms at great heights was much higher, clearly debunking such speculations. Saha gave this matter a great deal of thought and concluded that "It seems to be the general opinion of the astrophysicists that there is some sort of a repulsive force on the Sun which neutralizes the greater part of gravity. " In a short paper entitled On Radiation-Pressure and the Quantum Theory" contributed in 1919 to the Astrophysical Journal, Saha showed that what countered gravity was selective radiation pressure.
The idea of Radiation Pressure was by itself not new. It was a natural consequence of Maxwell's
Electromagnetic theory of light, and laboratory experiments had already been performed to demonstrate the existence of radiation pressure. However Maxwell's theory also predicted that when the size of the object is reduced, the pressure decreases, becoming vanishingly small when the size of the particle dwindles to that of an atom. Saha's theory seemed to contradict this because it claimed that radiation lifts the atoms up into the chromosphere in defiance of solar gravity. Saha explained this apparent difference: "An explanation of the existence of radiation-pressure on molecules is furnished when we apply the quantum theory in place of the old continuous theory of light."
According to him, following Einstein
and Planck
, one visualizes light energy to be composed of ‘localized in packets of energy hν’. Now supposing that one such pulse is absorbed by an atom of mass M. The light pulse comes with a momentum (hν/c), and when it is absorbed this momentum is transferred into the atom, which then moves with a velocity v = (hν/cM). However when actual values were substituted, the velocity came out to be rather small. Saha countered: "It should be remembered that v is really an impulsive velocity and is one of the nature of an acceleration. The total velocity acquired by a Hydrogen atom per second will depend upon the number of kicks of light it experiences per second, and provided this is sufficiently great the velocity acquired may rise to enormous values. " Thanks to such velocities, atoms could be carried away to long distances from the chromosphere, creating a blanket of atoms thicker than what the theory of Schwarzschild and its concomitants predicted. However as the atom will not absorb a light pulse of any arbitrary frequency ν but only a frequency that corresponds to one of the allowed transitions, in this respect the atom is choosy, and therefore selective. Other factors which govern the value of the pressure are:
In this way we can understand why Calcium is present at higher levels than hydrogen, it is because the radiation pressure on the former is more than on the latter. He described his findings in a paper entitled The Stationary H- and K-lines of Calcium in Stellar Atmosphere which he submitted to the Nature
magazine in 1921."
had garnered substantial attention so that many scientists were devoting their efforts to discern its mysteries. The foundations of the subject were laid by Fraunhofer
and Kirchhoff
. The next important landmarks was the work of Higgins and Miller who reported on the Fraunhofer spectra
of about fifty of the brightest stars. They concluded that all the stars they had examined had a chemical composition similar to the Sun
. By 1920, over two hundred thousand stars had been studied and classified. This spawned a general consensus that if one understood what was going on in the sun, one could figure out what was going in the stars as well. But in spite of the welter of information regarding it, the Sun remained an enigma. Lockyer
had said that lines (in the flash spectrum) originating at the top of the chromosphere were similar to those seen in spark spectra. He also said that the spark lines were enhanced, the enhancement being due to a stimulus, which he held, was temperature. However this theory had its detractors. It was conceivable that the enhancement came not only from high temperature, but some other agency was providing the stimulus as well. Saha later recalled:
and consult with other eminent astrophysicists to aid him in his research. He got hold of two books on astronomy by Agnes Clerke
, which furthered his interest in the subject. But he was short of money, so he had to compete for studentships and fellowships. Among other things, the competition required him to submit a technical essay and he wrote one entitled On the Harvard Classification of Stellar Spectra. Saha's essay was so much superior to the other entries that both the Premchand Roychand Studentship and the Guru Prasanna Ghosh Fellowship easily came to him. With some guarantee for money in pocket, he set sail for Europe in September 1919. After reaching London Saha realized that he was short of money of again, and something had to be done quickly both on the financial side and the scientific as well. Fortunately he ran into an ex-classmate who was then at the Imperial College
. He acquainted Saha with Prof.A.Fowler
, who himself was a famous stellar astrophysicist and a former assistant to Lockyer
. Fowler was impressed by his prize-winning essay and permitted him to work in his lab under his guidance. Under his guidance, Saha rewrote the essay, giving it a new title: On a Physical Theory of Stellar Spectra. Fowler communicated this paper to the Royal Society
, which promptly published it in its proceedings
; the paper attracted wide attention in America. This thesis won him the Griffith Prize of the Calcutta University in 1920." Saha later reminisced:
Commenting on the relationship, astronomer Dingle
once observed: "On thinking back to the relation which existed between Saha and Fowler, I am tempted to compare it with that between Maxwell
and Faraday
." In addition to this paper he also published three other papers on his astrophysical research in the first six months of 1920 in the Philosophical Magazine viz. Ionisation of the Solar Chromosphere (March 4, 1920), On Elements in the Sun (22 May 1920) and On the Problems of Temperature-Radiation of Gases (25 May 1920). In these papers Saha laid the foundation of what later came to be known as the Theory of Thermal Ionisation
. The absorption lines of stellar spectra differ widely, with some stars showing virtually nothing but hydrogen and helium lines while others show vast numbers of lines of different metals. Saha's great insight was to see that all these spectral lines could be represented as the result of ionization. He saw that the degree of ionization, i.e., the number of electrons stripped away from the nucleus, would depend primarily on temperature. As the temperature increases, so does the proportion of ionized atoms. The remaining neutral atoms will thus produce only weak absorption lines that, when the temperature gets high enough, will disappear entirely. But the singly, doubly, and even triply ionized atoms will absorb at different sets of wavelengths, and different sets of lines will appear in stellar spectra, becoming stronger as the proportions of these ions grow. He also formulated what is known as the Saha equation
. This equation is one of the basic tools for interpretation of the spectra of stars in astrophysics. By studying the spectra of various stars, one can find their temperature and from that, using Saha's equation, determine the ionisation state of the various elements making up the star.Besides continuing on his works in astrophysics, Saha was also keen to pursue experiments to verify his theory of thermal ionisation, which however called for advanced laboratories equipped with high-temperature facilities. Since such labs were not available in England, on Fowler's advice, Saha wrote to Nernst
, who promptly extended him an invitation to visit his lab and perform his experiments. Saha spent about a year in Nernst's lab and this proved an immense boon. Right next to the lab was held every week the University Colloquium, and he attended all of them. This enabled him to meet many eminent German physicists like Max Planck
, Max von Laue
and Einstein
. Meanwhile Saha sent a copy of his paper on his stellar spectra to Sommerfeld
who immediately invited him to Munich
to deliver a seminar. This was done in May and the lecture was published in the Zeitschrift fur Physik Vol 6. This visit coincided with that of Rabindranath Tagore
, whom Saha did not know at that time. Sommerfeld acquainted them; Tagore received him very affectionately, enquired about his work, and invited him to visit Santiniketan
on his return to India.
From Germany Saha went to Switzerland and then back to England, where he met Eddington at Cambridge
. Eddington invited him to his house, and there he was introduced to Milne, who was then Eddington's assistant. Milne told Saha that he had seen his paper on radiation pressure in Nature
and that he had done further work on the subject. Milne also added that he was collaborating with R.H.Fowler
on extending Saha's work. (In fact this theory has seen come to be known as Milne's theory of selective radiation pressure.) Saha later lamented: "I might claim to be the originator of the theory of Selective Radiation Pressure...Milne read a note of mine in nature and in his paper he mentioned my contribution in a footnote, though nobody appears to have noticed it."
suggested that the Mount Wilson Observatory
in America will be the best place for his kind of work and advised him to write to George Ellery Hale
, Director of the Mount Wilson Observatory. On 9 July 1921, Saha wrote to Hale: "I shall be very glad if someone at the Mount Wilson Solar Observatory undertakes the work suggested overleaf. My means are too limited and my university is poorly provided for astrophysical work, I see no prospects of ever being able to carry out the ideas contained in my papers. It will be a source of great pleasure for me to find that my exertions have resulted in throwing some light on some dark problems in astrophysics." In the enclosure he added his predictions made in his four papers published in the philosophical Magazine the previous year. There was no reply. However around this time Henry Norris Russell
of Princeton University
took quick and serious notice of Saha's work. He convinced Hale of the authenticity of Saha's work, and under their coordination, the general attack on spectra began in Mount Wilson Observatory. Saha however was not asked to join them. Hence he was resigned to wok with limited data and scientific instruments, which however did not deter him in the least. Meanwhile the Harvard College Observatory had accumulated mountains of data and Russell was concerned as to what it all meant. Between 1908 and 1913 he applied his mind vigorously to the problem and came to the conclusion that the data could be comprehensively represented as a map. Such a plot was independently developed by Hertzsprung
and so it is often called Hertzsprung–Russell diagram
. However, while making the plot, he found that most stars clustered in a band. This could not be the case unless the alphabets were in some mysterious way related to some physical parameter of the star. Pickering
and Cannon
proposed the Harvard Classification Scheme, because they observed that the spectra changed continuously across the sequence. But none was sure as to what caused this change. Russell suspected that it was the temperature of the stellar atmosphere that caused the change; he however could not explain how temperature variation caused a gradual change in the absorption spectra.
Russell, however, was not aware that Saha had already taken the first step in this direction in his prize-winning essay (under A.Fowler's guidance). Saha began that article by quoting Russell as follows: "The spectra of stars show remarkably few radical differences in type. More than 99% of them fall into one or the other of the six great groups which during the classic work of the Harvard College Observatory
...received designations...by the rather arbitrary letters B A F G K M. That there should be so few types is noteworthy, but much more remarkable is the fact that they form a continuous series... Russell is of the opinion that the principal differences in the stellar spectra arise in the main from variations in single physical variable in the stellar atmosphere...". In his paper Saha showed that
Although he was the one who originally conjured up the idea of converting the Harvard scale into a temperature scale, there were some practical difficulties, including in precisely determining when a line just disappears. Fowler
and Milne extended the formula by fixing the temperature scale after observing when the line intensity became maximum. Hence this achievement is generally attributed to this duo. Cecilia Payne-Gaposchkin
, who was then working in the Harvard College Observatory
later recollected:
as Khaira Professor of Physics, a new Chair created from the endowment of Kumar Guruprasad Singh of Khaira. However the university was going through acute financial crisis, made no better by the enmity of Lord Ronaldshay
, the then Governor of Bengal, towards Sir Ashutosh Mukherjee
, who was then serving his second term as the Vice Chancellor of the university. Saha was caught up in this turmoil and where he was concerned, he could not get an assistant, he could not buy equipment and he even had problems with lab space. Much as he loved Calcutta
, he concluded that he couldn't possibly continue his research there, and decided to leave. Offers came from Aligarh Muslim University
and Benaras Hindu University
, but he rejected both in favour of the Allahabad University
, chiefly because some of his friends were on the Executive Council of that university, who he hoped would assist him financially to conduct his researches. At Allahabad
before he could start research work he had to improve the workshop, the laboratory and the library. Moreover, he found hardly any time for research after discharging heavy teaching responsibilities. But Saha was not to be distracted by adverse conditions. And very soon research papers started appearing from Saha and his students. Among his collaborators at Allahabad were N.K. Sur, P.K. Kichlu, D.S. Kothari, R.C. Majumdar, K.B.Atmaram Mathur and B.D. Nag Choudhary. In 1927 the Italian Government organised a grand International Conference to commemorate the birth centenary of Alessandro Volta
. the venue was Como
, and the principal organiser was Fermi
. Saha got an invitation, and there he presented a paper on the analysis of complex spectra, that being then the topic of his interest. From Como, Saha proceeded to Oslo
in Norway to join an expedition organised by Prof.L.Vegard of Oslo University to observe a forthcoming total solar eclipse
. For this purpose, the party journeyed to Ringebu
.
The same year he became a fellow of the Royal Society of London
. He was also elected a life member of the Astronomical Society of France and was made a Foundation Fellow of the Institute of Physics
in London. This chanced him an audience with the then Governor of United Provinces
Sir William Sinclair Morris, and learning that he was once a classfellow of Ernest Rutherford
, took the opportunity to tell him about the poor condition of the lab. The Governor was moved and immediately sanctioned a research grant of Rs. 5000/- per month. Realising that this was by no means enough, he wrote to Sir Tej Bahadur Sapru, imploring him to write to the Central Government in Delhi
recommending a research grant. However his request fell to deaf ears, and so he turned to the Royal Society. Understanding his plight, the Society promptly granted a yearly sum of Rs. 1500/-, and now he could afford to concentrate fully on research work without monetary problems. In the next year 1932, he became the University Professor of Physics in the university.
Around this time Saha felt the necessity of developing a science academy to instill in the students the passion to pursue research and other innovative works. He was inspired in this idea by the successful heritage of similar academies like the Royal Society
in England, the French Academy of Sciences
in Paris, the Prussian Academy of Sciences
in Berlin, the Russian Academy of Sciences
in Moscow. The idea came to him when in 1930 the Indian Science Congress Association
met in Allahabad
under the presidentship of C. S. Christopher. Delivering an address on the occasion, the Governor Malcolm Hailey
said that if a scientific body could motivate research in the university departments and steer it for public benefit, then it might become possible for the Government to offer grants for research. Saha took this hint and thanks to his effort the U.P. Academy of Sciences
came into existence. Despite its name, National Academy of Sciences essentially functioned as a regional body. This prompted him to envision an organisation with an all-India character and thus in 1934 he proposed the founding of an Indian Academy of Sciences. On this issue there was strong difference of opinion between him and Raman and eventually Raman announced in Bangalore
the founding of the Indian Academy of Sciences
. This was unacceptable to Saha who continued his efforts and as a result there came into existence in 1935 the National Institute of Sciences, India with its headquarters in Calcutta
. The formation was formally announced on January 7 in the Senate Hall of the Calcutta University under the Chairmanship of the J.H. Hutton. L.L. Fermor was elected the first president of the Institute. The same year he also founded the Indian Science News Association at Calcutta. Its main objective was to disseminate science amongst the public.The Association started publishing its journal called Science and Culture. On receiving, a copy of the first issue of the Journal, Netaji Subhash Chandra Bose was impressed and he wrote: "The appearance of Science and Culture is to be warmly welcomed not only by those, who are interested in abstract science but also by those who are concerned with nationbuilding in practice. Whatever might have been the views of our older "Nation builders" we younger folk approach the task of nation building in a thoroughly scientific spirit and we desire to be armed with all the knowledge which modern science and culture can afford us. It is not possible however, for political workers with their unending preoccupations to glean that knowledge themselves, it is therefore, for scientists and scientific investigators to come in their rescue." Saha himself wrote more than 200 articles in Science and Culture on a wide range of topics which included: organization of scientific and industrial research, atomic energy and its industrial use, river valley development projects, planning the national economy, educational reforms and modification of Indian calendar. The journal is presently running in its 76th volume. Later, on his initiative, the headquarters of the National Institute of Sciences was shifted to Delhi May 1946 and the name was changed to the Indian National Science Academy
.
In 1936 Saha received a fellowship from the Carnegie Trust of the British Empire
, and he went on an extended outing that took him to countries like Iraq
, Syria
, Jordan
, Israel
. At Munich he was happily reunited with Sommerfeld
. He then proceeded to London to attend the centenary celebrations of the Physics society where Max Planck
was the chief guest. From London Saha went to Oxford
and spent a month in the company of Milne. Then he visited the Harvard College Observatory
in Boston
. here he met many noted scientists like Harlow Shapley
, Donald Menzel
, and Cecilia Payne-Gaposchkin
. Moving west, he made a grand tour visiting many observatories and meeting famous people like Hubble
, Walter Adams
, and lastly Lawrence
in Berkeley
. Saha and Lawrence had earlier met in Copenhagen
in 1927, but by now Lawrence was famous as the inventor of the cyclotron
. This contact proved useful and later Lawrence helped Saha to some extent to construct a cyclotron in Calcutta. From there, he went to Chicago
to visit the Yerkes Observatory
. Returning to Harvard, he attended the centenary celebrations of the Harvard University
. It was then he wrote a short note entitled A Stratosphere Solar Observatory, which was published in the Harvard College Observatory Bulletin, where he explicitly suggested the observation of the solar spectrum at a height greater than 40 km, for he reckoned it was the most plausible way to get out of the atmosphere and avoiding the UV depletion that otherwise results. While in Boston, he also visited the Massachusetts Institute of Technology
, the then President of which was Karl Taylor Compton
. Returning to Europe, he attended an international conference on nuclear physics in the Niels Bohr Institute
in Copenhagen. This was instrumental in shifting his focus to nuclear science later.
After his long but intellectually fulfilling tour, Saha returned to Allahabad in 1937. In 1938, he organised a symposium on "Power Supply" under the auspices of the Academy, and requested Nehru
to inaugurate it. Though at that point of time, Nehru and Saha shared a cordial relationship, it later turned sour, which considerably hindered the plans and propositions he wanted to advocate to employ nuclear science to public benefit.
During his time in Allahabad he rederived Dirac's
quantisation condition for magnetic monopole. Dirac was one of the first scientists to devote considerable attention to the study of magnetic monopole
. This led Saha to the observation that a particle could in principle have both electric charge and magnetic charge. Such a particle (hypothetical) would be called a dyon
. This quantisation condition on its charges as derived by Saha turned out to be an elegant generalisation of the principle proposed by Dirac.
Around this time, he felt constricted in Allahabad, and feeling that Calcutta would provide better opportunities to disseminate science, he returned to Calcutta in 1938.
was the Vice Chancellor of the University and who was soon to be succeeded by Sir Mohammad Azizul Haque
. After joining Saha immediately got involved in organizing research in the Palit Laboratory. He also took the task of remodeling the MSc syllabus in physics. Saha later introduced a general and a special paper in nuclear physics and a general paper in quantum mechanics in 1940.
, he sent in 1938 his student B.D.Nag Chowdhary to Berkeley to study and work under Lawrence
, and learn all he could about the cyclotron
. Saha was keen to have a cyclotron in the Calcutta University and used his influence with Nehru to persuade the Tatas
to give him a grant to build one. The Tatas obliged with Rs. 60,000/- which wasn't however sufficient to construct a cyclotron. In 1941 Nag Chowdhary returned, and thanks to his efforts in America, a consignment of cyclotron parts (mainly for making the magnet) soon followed. Meanwhile America entered the war and the ship carrying the next batch of equipments (mainly vacuum pumps) was sunk by the Japanese. This was major setback, and now there was no hope of getting any parts from America; anyway, American scientists, Lawrence included, had drifted towards the Manhattan Project
. The parts now all had to be made in Calcutta, and this proved to be an interminable affair. Eventually it took many years to complete (it started working after Saha passed away). Apart from this Saha also started on a modest scale some cosmic-ray observations in Darjeeling.
The event of the atom bomb dropping
on Japan made Saha further aware of the profound importance of nuclear energy. So he resolved to establish an autonomous institute under the umbrella of the university devoted exclusively to the study of nuclear science and its prospects. As a result the Saha Institute of Nuclear Physics
came into being in 1948. It was declared open by Irène Joliot-Curie
in 1950. As per the university regulations, Saha had to retire in 1952 both from the Palit Professorship and the post of the Director of the Institute of Nuclear Physics. However he retained links with both the institutes in honorary capacity.
. In 1944 he became its Honorary Secretary, and following the death of the president in 1946, himself became its president. At that time the IACS was located in Bowbazar
. Following the golden era in which Raman conducted his research there, the institute sort of plodded on, and Saha was keen to inject a fresh life into it by starting several new research programmes. all this took time and money, and eventually he persuaded the Government of West Bengal
to shift the institute to Jadavpur
after buying ten acres of land there. Obeying the Association rules, Saha stepped down as president in 1950. Meanwhile Shanti Swaroop Bhatnagar
, with whom he had maintained a cordial relation since meeting him in London in 1920, suggested that it was time that the IACS had a full time director. He further insisted that the post be offered to Saha so that he could complete the reorganisation work he had started earlier. Thus in 1953, Saha became the first director of IACS, a post he held till his death in 1956.
and Meitner
in 1939 and the stupefying possibilities this discovery was pregnant with. Meanwhile in 1940 the British rulers in Delhi formed a Board for scientific and Industrial Research (BSIR) with Bhatnagar as the head. Saha was invited to be a member. In 1942, the Government constituted a superior body called CSIR where once again Saha was made a member.
By 1944 it became clear that the tide of fortune in the war was turning against Germany and Japan. In anticipation of victory, the British Government began to make plans for post-war reconstructions. As a part of the process, it asked the Royal Society
to send Prof. A.V. Hill to India to advise the government. Hill came and met many scientists, Saha included. He then recommended that an Indian Scientific Mission (ISM) be sent abroad to observe scientific and industrial progress and make post-war plans. The recommendation was accepted and a delegation left India in October 1944; Saha was a member of the ISM.
The tour took the mission to several countries including America. While there, Saha made enquiries about research on atomic energy but drew a blank. He did not know it right then that the Manhattan Project
was going on in full swing and atomic energy research was the most closely guarded secret. His enquiries prompted the FBI to interrogate him to gather how much he really knew about their project. However they were relieved that he knew nothing, though his knowledge and expertise on the matter astounded them. On return to India the ISM prepared an official report and submitted it to the Government; the report was drafted by Saha. In 1947 India became free and Nehru
became the Prime Minister
of India. Atomic energy was the new hope and as member of the BSIR, Saha had every reason to hope that he would be able to play a key role in the development of atomic energy in India. Bhabha
also had similar thoughts and he too began to offer Nehru ideas on the subject. In 1948, Saha was formally asked by the Government of India at Nehru's insistence about the formation of Atomic Energy Commission
which Bhabha had suggested. Saha firmly opposed the idea on the grounds that India lacked the required industrial base to augment it, and that trained manpower was not available. In his view, before launching a full-fledged atomic energy programme, the industry ought to build up first, and Nuclear physics-oriented courses should be introduced in various universities to obtain a competent manpower. He strongly advocated the French model of atomic energy development which was in fact the brainchild of his friend Frédéric Joliot-Curie
. Bhabha, on the other hand, was a proponent of a much faster and more vigorous programme of development which appealed to Nehru. As a result the Atomic Energy Commission was set up in 1948 and the Atomic Energy Establishment, Trombay
in 1954.
he made this topic the theme of his discourse and highlighted the danger posed by recurrent floods in Indian rivers, particularly in the deltaic ones. After the 1923 flood, Saha witnessed two major floods in 1931 and 1935. In 1943 the flood in Bengal isolated Kolkata from rest of India and Saha wrote extensively on the issue. Saha's writings and speeches made the government realize the gravity of the situation. As a result the Damodar Valley Enquiry Committee came into being in 1943. The Committee was chaired by the Maharaja of Burdwan. Saha was also a member of the Committee. Saha presented a plan for handling the Damodar
river system before the Committee. He also wrote extensively on river control based on modern science and technology. He argued that the model of Tennessee river system under the Tennessee Valley Authority
(TVA) in United States could be adapted to the Damodar Valley. The Central Government
appointed a technical advisory committee in 1945 under the chairmanship of Mr. H.M.Mathews. Another member of the committee was Mr.W.L.Voorduin, who had earlier served on TVA. The committee supported the claims of Saha, and at the instance of Dr. B. R. Ambedkar
, the then member-in-charge of power and works in the Viceroy's cabinet, the Government adopted a resolution to set up a Damodar Valley Corporation
(DVC) after the model of TVA. The DVC was set up in March 1948.
, now a favourite of Nehru and closely associated with the Planning Commission. Enroute to the office he collapsed. He was rushed to the hospital, but he never recovered.
four times- 1930, 1937, 1939, 1940.". It is said that the prize committee was of the opinion that one winner in a century from India was more than what Physics could tolerate.
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n astrophysicist best known for his development of the Saha equation
Saha ionization equation
The Saha ionization equation, also known as the Saha–Langmuir equation, was developed by the Indian astrophysicist Meghnad Saha in 1920, and later by Irving Langmuir. One of the important applications of the equation was in explaining the spectral classification of stars...
, used to describe chemical and physical conditions in stars.
Early life
Meghnad Saha was born in a small village named Seoratali, about 40 km from DhakaDhaka
Dhaka is the capital of Bangladesh and the principal city of Dhaka Division. Dhaka is a megacity and one of the major cities of South Asia. Located on the banks of the Buriganga River, Dhaka, along with its metropolitan area, had a population of over 15 million in 2010, making it the largest city...
(in present Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
). The youngest of the five sons of Jagannath Saha and Bhubaneswari Debi, Meghnad belonged to a poor family and struggled to rise in life. His father was reluctant to allow him to undergo higher education; he wanted him to assist him in shopkeeping. With some persuasion from his eldest son Jayant and Meghnad's primary school teachers, he relented, and Meghnad went to the neighbouring village to live there and attend an English-medium school. Here he was lucky in that one Mr. Ananta Kumar Das, a medical practitioner, took interest in Meghnad and offered him free boarding and lodging. In 1905, he joined the Dhaka Collegiate School
Dhaka Collegiate School
Dhaka Collegiate School is a secondary school in Dhaka, Bangladesh. It is the oldest school in Dhaka and one of the oldest and prestigious institutions in the country for more than a century.-History:...
. Here he not only received a free studentship, but also a stipend. However he lost both his free studentship and stipend when he participated in a boycott against the then British Governor of Bengal Sir Bampfylde Fuller when he came on a visit to Dacca. He managed to pull through by joining the Kishorilal Jubilee School where he again received a free studentship and a stipend. Around this time Saha joined the Bible classes run by the Dacca Baptist Society. In a test that was conducted, Saha stood first and won a handsome prize of Rs.100/- plus a beautifully bound copy of the Bible
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...
. In 1909 Saha passed the Collegiate entrance exam, standing first among the students from East Bengal, with highest marks in Mathematics, English, Sanskrit and Bengali. This got him entry into the Intermediate Dhaka College
Dhaka College
, located in Dhaka, is one of Bangladesh's earliest and most prestigious higher educational institutions. It offers both four years bachelor's and one years masters course in various majors, but it is best known for HSC...
, where he spent two years studying Intermediate. During this time he also took private lessons in German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
which later was to stand him in good stead.
In 1911 he ranked third in the ISC exam. In the same year Saha came to Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...
and joined the Presidency College
Presidency College, Kolkata
Presidency University, Kolkata, formerly Hindu College and Presidency College, is a unitary, state aided university, located in Kolkata, West Bengal. and one of the premier institutes of learning of liberal arts and sciences in India. In 2002 it was ranked number one by the weekly news magazine...
to study for the B.Sc. degree in Applied Mathematics
Applied mathematics
Applied mathematics is a branch of mathematics that concerns itself with mathematical methods that are typically used in science, engineering, business, and industry. Thus, "applied mathematics" is a mathematical science with specialized knowledge...
. Presidency College by then had spawned numerous luminaries, and Saha found himself surrounded by many: Satyendra Nath Bose
Satyendra Nath Bose
Satyendra Nath Bose FRS was an Indian mathematician and physicist noted for his collaboration with Albert Einstein in developing a theory regarding the gaslike qualities of electromagnetic radiation. He is best known for his work on quantum mechanics in the early 1920s, providing the foundation...
, Jnan Ghosh, N.R. Sen, and J. N. Mukherjee were his classmates, P.C. Mahalanobis was one year his senior, N. R. Dhar was senior by two years, while Netaji Subhash Chandra Bose was one year his junior. His teachers included Jagadish Chandra Bose in physics, Prafulla Chandra Roy
Prafulla Chandra Roy
Prafulla Chandra Ray was a Indian academician, a chemist and entrepreneur. He was the founder of Bengal Chemicals & Pharmaceuticals, India's first pharmaceutical company...
in chemistry, D.N. Mallik and C. E. Cullis in mathematics. After B.Sc. came M.Sc. and once again S.N. Bose was his classmate. In M.Sc. and B.Sc. Saha secured the second rank, while Bose stood first, while in the M.sc. exam both stood first, Bose in Pure Mathematics and Saha in Applied Mathematics.
While in college during 1913 through 1915, Meghnad got involved with Anushilan Samiti
Anushilan Samiti
Anushilan Samiti was an armed anti-British organisation in Bengal and the principal secret revolutionary organisation operating in the region in the opening years of the 20th century. This association, like its offshoot the Jugantar, operated under the guise of suburban fitness club...
to take part in freedom fighting movement. Bagha Jatin
Bagha Jatin
Bagha Jatin , born Jatindranath Mukherjee was an Bengali revolutionary philosopher against British rule....
, a famous freedom fighter, was used to visit his hostel for building student organization., Saha flirted a bit with the idea of joining hands with revolutionaries in their fight against the British. However he soon gave up on the idea, his goal was to get a job, earn money and support his family. After college he tried to enter the Indian Finance Service, but he was denied permission to appear in the exam as he was suspected of having contacts with revolutionaries; besides, there was also the boycott he had participated in as a school student. In order to procure some income, he started giving private tutions. It was around this time that Sir Ashutosh Mukherjee
Ashutosh Mukherjee
Sir Ashutosh Mukherjee, CIE was a prolific Bengali educator and the first Indian Vice Chancellor of the University of Calcutta from 1906 to 1924. Perhaps the most emphatic figure of Indian education, he was a man of great personality, high self-respect, courage and towering administrative ability...
became the Vice Chancellor of Calcutta University
University of Calcutta
The University of Calcutta is a public university located in the city of Kolkata , India, founded on 24 January 1857...
, and he opened a new College of Science for post-graduate studies and research - this was made possible because of the magnificent donations of two eminent lawyers of Calcutta, Tarak Nath Palit and Rash Behari Ghose. He offered lecturerships to both Saha and Bose in the Department of Mathematics in this college but because they could not get along with Dr. Ganesh Prasad
Ganesh Prasad
Ganesh Prasad was an Indian mathematician who specialized in the theory of potentials, theory of functions of a real variable, Fourier series and the theory of surfaces. He was trained at the Universities of Cambridge and Göttingen and on return to India he helped develop the culture of...
, the professor, he transferred them to the Physics Department where C.V. Raman had been appointed the Palit Professor. In later life he was close to Amiya Charan Banerjee
Amiya Charan Banerjee
Amiya Charan Banerjee was a mathematician and educator popularly known as A.C.Banerjee or simply as Professor Banerjee.-Family background:...
, a renowned mathematician at Allahabad University.
Selective Radiation Pressure
Shortly after the end of the First World War there was announced the momentous discovery of the deflexion of starlight by the gravitational field of the sun, confirming Einstein's theory of general relativityGeneral relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
. Saha got deeply interested in the relativity theory. He, jointly with S. N. Bose, prepared an English translation of Einstein's papers, later published in the form of a book by the University of Calcutta
University of Calcutta
The University of Calcutta is a public university located in the city of Kolkata , India, founded on 24 January 1857...
. The study of relativity led Saha to some investigations in electromagnetic theory and his first original paper entitled On Maxwell's stresses appeared in the Philosophical Magazine in 1917 and quickly followed it up with several more in the next couple of years. This was followed by papers on the dynamics of the electron. He derived, on the basis of the Special theory of Relativity
Special relativity
Special relativity is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".It generalizes Galileo's...
, the Liénard–Wiechert potential due to a point-charge. During these years he also worked on radiation pressure, and in 1918 (with S. Chakravorti) he published in the Journal of the Royal Asiatic Society of Bengal (Calcutta) a paper on the measurement of the pressure of light using a resonance method. These were substantial enough for the Calcutta University to award him the D.Sc. degree in 1918. In between, Saha got married to Radharani (he had believed that a celibate life was most fit for him until he read The Cloister and the Hearth
The Cloister and the Hearth
The Cloister and the Hearth is a historical novel by the English author Charles Reade. Set in the 15th century, it relates the story revolving about the travels of a young scribe and illuminator, Gerard Eliassoen, through several European countries. The Cloister and the Hearth often describes the...
, which resolved him to marry). At this point of time he became interested in the phenomenon of selective radiation pressure. The question that piqued his curiosity was that how come a heavier element like Calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
is present up to a greater height compared to a lighter element like Hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
, apparently defying gravity. He had read in Agnes Clerke's book about the ‘hypothetical levitative force’ which apparently acted on atoms of some elements only, e.g. calcium. Several models had already been proposed to explain this anomaly, all of them banking on the possibility of a sharp decrease of density with increase in height that might negate the effect of increased weight of the element. One such model suggested by Schwarzschild
Karl Schwarzschild
Karl Schwarzschild was a German physicist. He is also the father of astrophysicist Martin Schwarzschild.He is best known for providing the first exact solution to the Einstein field equations of general relativity, for the limited case of a single spherical non-rotating mass, which he accomplished...
predicted that at a height of around 3500 km, there would be only one atom in a billion cubic metres. However the flash spectra showed that the abundance of atoms at great heights was much higher, clearly debunking such speculations. Saha gave this matter a great deal of thought and concluded that "It seems to be the general opinion of the astrophysicists that there is some sort of a repulsive force on the Sun which neutralizes the greater part of gravity. " In a short paper entitled On Radiation-Pressure and the Quantum Theory" contributed in 1919 to the Astrophysical Journal, Saha showed that what countered gravity was selective radiation pressure.
The idea of Radiation Pressure was by itself not new. It was a natural consequence of Maxwell's
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
Electromagnetic theory of light, and laboratory experiments had already been performed to demonstrate the existence of radiation pressure. However Maxwell's theory also predicted that when the size of the object is reduced, the pressure decreases, becoming vanishingly small when the size of the particle dwindles to that of an atom. Saha's theory seemed to contradict this because it claimed that radiation lifts the atoms up into the chromosphere in defiance of solar gravity. Saha explained this apparent difference: "An explanation of the existence of radiation-pressure on molecules is furnished when we apply the quantum theory in place of the old continuous theory of light."
According to him, following Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
and Planck
Max Planck
Max Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came...
, one visualizes light energy to be composed of ‘localized in packets of energy hν’. Now supposing that one such pulse is absorbed by an atom of mass M. The light pulse comes with a momentum (hν/c), and when it is absorbed this momentum is transferred into the atom, which then moves with a velocity v = (hν/cM). However when actual values were substituted, the velocity came out to be rather small. Saha countered: "It should be remembered that v is really an impulsive velocity and is one of the nature of an acceleration. The total velocity acquired by a Hydrogen atom per second will depend upon the number of kicks of light it experiences per second, and provided this is sufficiently great the velocity acquired may rise to enormous values. " Thanks to such velocities, atoms could be carried away to long distances from the chromosphere, creating a blanket of atoms thicker than what the theory of Schwarzschild and its concomitants predicted. However as the atom will not absorb a light pulse of any arbitrary frequency ν but only a frequency that corresponds to one of the allowed transitions, in this respect the atom is choosy, and therefore selective. Other factors which govern the value of the pressure are:
- How many photonPhotonIn physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s there are at frequency ν in the spectrum coming out of the photosphere. - What sort of absorption frequencies are available to the atom.
- How intense is the Blackbody spectrum at those frequencies.
In this way we can understand why Calcium is present at higher levels than hydrogen, it is because the radiation pressure on the former is more than on the latter. He described his findings in a paper entitled The Stationary H- and K-lines of Calcium in Stellar Atmosphere which he submitted to the Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
magazine in 1921."
The Chromosphere Puzzle
By 1915, the subject of Stellar SpectroscopyAstronomical spectroscopy
Astronomical spectroscopy is the technique of spectroscopy used in astronomy. The object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other celestial objects...
had garnered substantial attention so that many scientists were devoting their efforts to discern its mysteries. The foundations of the subject were laid by Fraunhofer
Joseph von Fraunhofer
Joseph von Fraunhofer was a German optician. He is known for the discovery of the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.-Biography:Fraunhofer was born in Straubing, Bavaria...
and Kirchhoff
Gustav Kirchhoff
Gustav Robert Kirchhoff was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects...
. The next important landmarks was the work of Higgins and Miller who reported on the Fraunhofer spectra
Fraunhofer lines
In physics and optics, the Fraunhofer lines are a set of spectral lines named for the German physicist Joseph von Fraunhofer . The lines were originally observed as dark features in the optical spectrum of the Sun....
of about fifty of the brightest stars. They concluded that all the stars they had examined had a chemical composition similar to the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. By 1920, over two hundred thousand stars had been studied and classified. This spawned a general consensus that if one understood what was going on in the sun, one could figure out what was going in the stars as well. But in spite of the welter of information regarding it, the Sun remained an enigma. Lockyer
Joseph Norman Lockyer
Sir Joseph Norman Lockyer, FRS , known simply as Norman Lockyer, was an English scientist and astronomer. Along with the French scientist Pierre Janssen he is credited with discovering the gas helium...
had said that lines (in the flash spectrum) originating at the top of the chromosphere were similar to those seen in spark spectra. He also said that the spark lines were enhanced, the enhancement being due to a stimulus, which he held, was temperature. However this theory had its detractors. It was conceivable that the enhancement came not only from high temperature, but some other agency was providing the stimulus as well. Saha later recalled:
European sojourn and Thermal Ionisation
Saha now realized that in order to delve deeply into the matter, he should go to EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and consult with other eminent astrophysicists to aid him in his research. He got hold of two books on astronomy by Agnes Clerke
Agnes Mary Clerke
Agnes Mary Clerke was an astronomer and writer, mainly in the field of astronomy. She was born in Skibbereen, County Cork, Ireland, and died in London.- Life and work :...
, which furthered his interest in the subject. But he was short of money, so he had to compete for studentships and fellowships. Among other things, the competition required him to submit a technical essay and he wrote one entitled On the Harvard Classification of Stellar Spectra. Saha's essay was so much superior to the other entries that both the Premchand Roychand Studentship and the Guru Prasanna Ghosh Fellowship easily came to him. With some guarantee for money in pocket, he set sail for Europe in September 1919. After reaching London Saha realized that he was short of money of again, and something had to be done quickly both on the financial side and the scientific as well. Fortunately he ran into an ex-classmate who was then at the Imperial College
Imperial College London
Imperial College London is a public research university located in London, United Kingdom, specialising in science, engineering, business and medicine...
. He acquainted Saha with Prof.A.Fowler
Alfred Fowler
Alfred Fowler, FRS was an English astronomer. Not to be confused with American astrophysicist William Alfred Fowler....
, who himself was a famous stellar astrophysicist and a former assistant to Lockyer
Joseph Norman Lockyer
Sir Joseph Norman Lockyer, FRS , known simply as Norman Lockyer, was an English scientist and astronomer. Along with the French scientist Pierre Janssen he is credited with discovering the gas helium...
. Fowler was impressed by his prize-winning essay and permitted him to work in his lab under his guidance. Under his guidance, Saha rewrote the essay, giving it a new title: On a Physical Theory of Stellar Spectra. Fowler communicated this paper to the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
, which promptly published it in its proceedings
Proceedings of the Royal Society
Proceedings of the Royal Society is the parent title of two scientific journals published by the Royal Society, whereas its initial journal, Philosophical Transactions, is now devoted to special thematic issues...
; the paper attracted wide attention in America. This thesis won him the Griffith Prize of the Calcutta University in 1920." Saha later reminisced:
Commenting on the relationship, astronomer Dingle
Herbert Dingle
Herbert Dingle , an English physicist and natural philosopher, who served as president of the Royal Astronomical Society from 1951 to 1953, is best known for his opposition to Albert Einstein's special theory of relativity and the protracted controversy that this provoked.-Biography:Dingle was born...
once observed: "On thinking back to the relation which existed between Saha and Fowler, I am tempted to compare it with that between Maxwell
James Clerk Maxwell
James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...
and Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
." In addition to this paper he also published three other papers on his astrophysical research in the first six months of 1920 in the Philosophical Magazine viz. Ionisation of the Solar Chromosphere (March 4, 1920), On Elements in the Sun (22 May 1920) and On the Problems of Temperature-Radiation of Gases (25 May 1920). In these papers Saha laid the foundation of what later came to be known as the Theory of Thermal Ionisation
Thermal ionization
In thermal ionization, also referred to as surface ionization, chemically-purified material loaded onto a filament which is then heated to cause some of the material to be ionized as it boils off the hot filament...
. The absorption lines of stellar spectra differ widely, with some stars showing virtually nothing but hydrogen and helium lines while others show vast numbers of lines of different metals. Saha's great insight was to see that all these spectral lines could be represented as the result of ionization. He saw that the degree of ionization, i.e., the number of electrons stripped away from the nucleus, would depend primarily on temperature. As the temperature increases, so does the proportion of ionized atoms. The remaining neutral atoms will thus produce only weak absorption lines that, when the temperature gets high enough, will disappear entirely. But the singly, doubly, and even triply ionized atoms will absorb at different sets of wavelengths, and different sets of lines will appear in stellar spectra, becoming stronger as the proportions of these ions grow. He also formulated what is known as the Saha equation
Saha ionization equation
The Saha ionization equation, also known as the Saha–Langmuir equation, was developed by the Indian astrophysicist Meghnad Saha in 1920, and later by Irving Langmuir. One of the important applications of the equation was in explaining the spectral classification of stars...
. This equation is one of the basic tools for interpretation of the spectra of stars in astrophysics. By studying the spectra of various stars, one can find their temperature and from that, using Saha's equation, determine the ionisation state of the various elements making up the star.Besides continuing on his works in astrophysics, Saha was also keen to pursue experiments to verify his theory of thermal ionisation, which however called for advanced laboratories equipped with high-temperature facilities. Since such labs were not available in England, on Fowler's advice, Saha wrote to Nernst
Walther Nernst
Walther Hermann Nernst FRS was a German physical chemist and physicist who is known for his theories behind the calculation of chemical affinity as embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize in chemistry...
, who promptly extended him an invitation to visit his lab and perform his experiments. Saha spent about a year in Nernst's lab and this proved an immense boon. Right next to the lab was held every week the University Colloquium, and he attended all of them. This enabled him to meet many eminent German physicists like Max Planck
Max Planck
Max Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came...
, Max von Laue
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...
and Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
. Meanwhile Saha sent a copy of his paper on his stellar spectra to Sommerfeld
Arnold Sommerfeld
Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...
who immediately invited him to Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...
to deliver a seminar. This was done in May and the lecture was published in the Zeitschrift fur Physik Vol 6. This visit coincided with that of Rabindranath Tagore
Rabindranath Tagore
Rabindranath Tagore , sobriquet Gurudev, was a Bengali polymath who reshaped his region's literature and music. Author of Gitanjali and its "profoundly sensitive, fresh and beautiful verse", he became the first non-European Nobel laureate by earning the 1913 Prize in Literature...
, whom Saha did not know at that time. Sommerfeld acquainted them; Tagore received him very affectionately, enquired about his work, and invited him to visit Santiniketan
Santiniketan
Santiniketan is a small town near Bolpur in the Birbhum district of West Bengal, India, approximately 180 kilometres north of Kolkata . It was made famous by Nobel Laureate Rabindranath Tagore, whose vision became what is now a university town that attracts thousands of visitors each year...
on his return to India.
From Germany Saha went to Switzerland and then back to England, where he met Eddington at Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...
. Eddington invited him to his house, and there he was introduced to Milne, who was then Eddington's assistant. Milne told Saha that he had seen his paper on radiation pressure in Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
and that he had done further work on the subject. Milne also added that he was collaborating with R.H.Fowler
Ralph H. Fowler
Sir Ralph Howard Fowler OBE FRS was a British physicist and astronomer.-Education:Fowler was initially educated at home but then attended Evans' preparatory school at Horris Hill and Winchester College...
on extending Saha's work. (In fact this theory has seen come to be known as Milne's theory of selective radiation pressure.) Saha later lamented: "I might claim to be the originator of the theory of Selective Radiation Pressure...Milne read a note of mine in nature and in his paper he mentioned my contribution in a footnote, though nobody appears to have noticed it."
Stellar Spectroscopy
Before leaving for Germany, Prof. H.H.Turner of OxfordUniversity of Oxford
The University of Oxford is a university located in Oxford, United Kingdom. It is the second-oldest surviving university in the world and the oldest in the English-speaking world. Although its exact date of foundation is unclear, there is evidence of teaching as far back as 1096...
suggested that the Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...
in America will be the best place for his kind of work and advised him to write to George Ellery Hale
George Ellery Hale
George Ellery Hale was an American solar astronomer.-Biography:Hale was born in Chicago, Illinois. He was educated at MIT, at the Observatory of Harvard College, , and at Berlin . As an undergraduate at MIT, he is known for inventing the spectroheliograph, with which he made his discovery of...
, Director of the Mount Wilson Observatory. On 9 July 1921, Saha wrote to Hale: "I shall be very glad if someone at the Mount Wilson Solar Observatory undertakes the work suggested overleaf. My means are too limited and my university is poorly provided for astrophysical work, I see no prospects of ever being able to carry out the ideas contained in my papers. It will be a source of great pleasure for me to find that my exertions have resulted in throwing some light on some dark problems in astrophysics." In the enclosure he added his predictions made in his four papers published in the philosophical Magazine the previous year. There was no reply. However around this time Henry Norris Russell
Henry Norris Russell
Henry Norris Russell was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram . In 1923, working with Frederick Saunders, he developed Russell–Saunders coupling which is also known as LS coupling.-Biography:Russell was born in 1877 in Oyster Bay, New...
of Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
took quick and serious notice of Saha's work. He convinced Hale of the authenticity of Saha's work, and under their coordination, the general attack on spectra began in Mount Wilson Observatory. Saha however was not asked to join them. Hence he was resigned to wok with limited data and scientific instruments, which however did not deter him in the least. Meanwhile the Harvard College Observatory had accumulated mountains of data and Russell was concerned as to what it all meant. Between 1908 and 1913 he applied his mind vigorously to the problem and came to the conclusion that the data could be comprehensively represented as a map. Such a plot was independently developed by Hertzsprung
Ejnar Hertzsprung
Ejnar Hertzsprung was a Danish chemist and astronomer.Hertzsprung was born in Copenhagen. In the period 1911–1913, together with Henry Norris Russell, he developed the Hertzsprung–Russell diagram....
and so it is often called Hertzsprung–Russell diagram
Hertzsprung–Russell diagram
The Hertzsprung–Russell diagram is a scatter graph of stars showing the relationship between the stars' absolute magnitudes or luminosities versus their spectral types or classifications and effective temperatures. Hertzsprung–Russell diagrams are not pictures or maps of the locations of the stars...
. However, while making the plot, he found that most stars clustered in a band. This could not be the case unless the alphabets were in some mysterious way related to some physical parameter of the star. Pickering
Edward Charles Pickering
Edward Charles Pickering was an American astronomer and physicist, brother of William Henry Pickering.Along with Carl Vogel, Pickering discovered the first spectroscopic binary stars. He wrote Elements of Physical Manipulations .Pickering attended Boston Latin School, and received his B.S. from...
and Cannon
Annie Jump Cannon
Annie Jump Cannon was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification. With Edward C...
proposed the Harvard Classification Scheme, because they observed that the spectra changed continuously across the sequence. But none was sure as to what caused this change. Russell suspected that it was the temperature of the stellar atmosphere that caused the change; he however could not explain how temperature variation caused a gradual change in the absorption spectra.
Russell, however, was not aware that Saha had already taken the first step in this direction in his prize-winning essay (under A.Fowler's guidance). Saha began that article by quoting Russell as follows: "The spectra of stars show remarkably few radical differences in type. More than 99% of them fall into one or the other of the six great groups which during the classic work of the Harvard College Observatory
Harvard College Observatory
The Harvard College Observatory is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, USA, and was founded in 1839...
...received designations...by the rather arbitrary letters B A F G K M. That there should be so few types is noteworthy, but much more remarkable is the fact that they form a continuous series... Russell is of the opinion that the principal differences in the stellar spectra arise in the main from variations in single physical variable in the stellar atmosphere...". In his paper Saha showed that
- His analysis substantiated Russell's views that continuous variation of stellar spectra among the various types was due to the variation of a single parameter.
- The parameter in question was temperature.
- He could convert the arbitrary Harvard scale of alphabets into a temperature scale based on spectral information by the method of marginal displacement.
Although he was the one who originally conjured up the idea of converting the Harvard scale into a temperature scale, there were some practical difficulties, including in precisely determining when a line just disappears. Fowler
Ralph H. Fowler
Sir Ralph Howard Fowler OBE FRS was a British physicist and astronomer.-Education:Fowler was initially educated at home but then attended Evans' preparatory school at Horris Hill and Winchester College...
and Milne extended the formula by fixing the temperature scale after observing when the line intensity became maximum. Hence this achievement is generally attributed to this duo. Cecilia Payne-Gaposchkin
Cecilia Payne-Gaposchkin
-Further reading:*Rubin, Vera , "Cecilia Payne-Gaposchkin" in OUT OF THE SHADOWS: Contributions of 20th Century Women to Physics, Nina Byers and Gary Williams, ed., Cambridge University Press ....
, who was then working in the Harvard College Observatory
Harvard College Observatory
The Harvard College Observatory is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, USA, and was founded in 1839...
later recollected:
In Allahabad
In November 1921 Saha returned to India and joined the Calcutta UniversityUniversity of Calcutta
The University of Calcutta is a public university located in the city of Kolkata , India, founded on 24 January 1857...
as Khaira Professor of Physics, a new Chair created from the endowment of Kumar Guruprasad Singh of Khaira. However the university was going through acute financial crisis, made no better by the enmity of Lord Ronaldshay
Lawrence Dundas, 2nd Marquess of Zetland
Laurence John Lumley Dundas, 2nd Marquess of Zetland KG, GCSI, GCIE, PC, DL, JP , styled Lord Dundas until 1892 and Earl of Ronaldshay between 1892 and 1929, was a British Conservative politician...
, the then Governor of Bengal, towards Sir Ashutosh Mukherjee
Ashutosh Mukherjee
Sir Ashutosh Mukherjee, CIE was a prolific Bengali educator and the first Indian Vice Chancellor of the University of Calcutta from 1906 to 1924. Perhaps the most emphatic figure of Indian education, he was a man of great personality, high self-respect, courage and towering administrative ability...
, who was then serving his second term as the Vice Chancellor of the university. Saha was caught up in this turmoil and where he was concerned, he could not get an assistant, he could not buy equipment and he even had problems with lab space. Much as he loved Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...
, he concluded that he couldn't possibly continue his research there, and decided to leave. Offers came from Aligarh Muslim University
Aligarh Muslim University
Aligarh Muslim University ,is a residential academic university, established in 1875 by Sir Syed Ahmed Khan as Mohammedan Angelo-Oriental College and later granted the status of Central University by an Act of the Indian Parliament in 1920...
and Benaras Hindu University
Banaras Hindu University
Banaras Hindu University is a public university located in Varanasi, India and is one of the Central Universities of India. It is the largest residential university in Asia, with over 24,000 students in its campus. BHU was founded in 1916 by Pandit Madan Mohan Malviya under the Parliamentary...
, but he rejected both in favour of the Allahabad University
Allahabad University
Allahabad University , is a premier Central University located in Allahabad, Uttar Pradesh, India. Its origins lie in the Muir Central College, named after Lt...
, chiefly because some of his friends were on the Executive Council of that university, who he hoped would assist him financially to conduct his researches. At Allahabad
Allahabad
Allahabad , or Settled by God in Persian, is a major city of India and is one of the main holy cities of Hinduism. It was renamed by the Mughals from the ancient name of Prayaga , and is by some accounts the second-oldest city in India. It is located in the north Indian state of Uttar Pradesh,...
before he could start research work he had to improve the workshop, the laboratory and the library. Moreover, he found hardly any time for research after discharging heavy teaching responsibilities. But Saha was not to be distracted by adverse conditions. And very soon research papers started appearing from Saha and his students. Among his collaborators at Allahabad were N.K. Sur, P.K. Kichlu, D.S. Kothari, R.C. Majumdar, K.B.Atmaram Mathur and B.D. Nag Choudhary. In 1927 the Italian Government organised a grand International Conference to commemorate the birth centenary of Alessandro Volta
Alessandro Volta
Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:...
. the venue was Como
Como
Como is a city and comune in Lombardy, Italy.It is the administrative capital of the Province of Como....
, and the principal organiser was Fermi
Enrico Fermi
Enrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
. Saha got an invitation, and there he presented a paper on the analysis of complex spectra, that being then the topic of his interest. From Como, Saha proceeded to Oslo
Oslo
Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King...
in Norway to join an expedition organised by Prof.L.Vegard of Oslo University to observe a forthcoming total solar eclipse
Solar eclipse of June 29, 1927
A total solar eclipse occurred on June 29, 1927. The path of totality crossed far northern Europe and Asia. This was the first total eclipse visible from British mainland soil for 203 years.-References:* *...
. For this purpose, the party journeyed to Ringebu
Ringebu
is a municipality in Oppland county, Norway. It is part of the traditional region of Gudbrandsdal. The administrative centre of the municipality is the village of Vålebru.The municipality of Ringebu was established on 1 January 1838...
.
The same year he became a fellow of the Royal Society of London
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
. He was also elected a life member of the Astronomical Society of France and was made a Foundation Fellow of the Institute of Physics
Institute of Physics
The Institute of Physics is a scientific charity devoted to increasing the practice, understanding and application of physics. It has a worldwide membership of around 40,000....
in London. This chanced him an audience with the then Governor of United Provinces
United Provinces of British India
The United Provinces of British India, more commonly known as the United Provinces, was a province of British India, which came into existence on 3 January 1921 as a result of the renaming of the United Provinces of Agra and Oudh. It corresponded approximately to the combined regions of the...
Sir William Sinclair Morris, and learning that he was once a classfellow of Ernest Rutherford
Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson OM, FRS was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics...
, took the opportunity to tell him about the poor condition of the lab. The Governor was moved and immediately sanctioned a research grant of Rs. 5000/- per month. Realising that this was by no means enough, he wrote to Sir Tej Bahadur Sapru, imploring him to write to the Central Government in Delhi
Delhi
Delhi , officially National Capital Territory of Delhi , is the largest metropolis by area and the second-largest by population in India, next to Mumbai. It is the eighth largest metropolis in the world by population with 16,753,265 inhabitants in the Territory at the 2011 Census...
recommending a research grant. However his request fell to deaf ears, and so he turned to the Royal Society. Understanding his plight, the Society promptly granted a yearly sum of Rs. 1500/-, and now he could afford to concentrate fully on research work without monetary problems. In the next year 1932, he became the University Professor of Physics in the university.
Around this time Saha felt the necessity of developing a science academy to instill in the students the passion to pursue research and other innovative works. He was inspired in this idea by the successful heritage of similar academies like the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in England, the French Academy of Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
in Paris, the Prussian Academy of Sciences
Prussian Academy of Sciences
The Prussian Academy of Sciences was an academy established in Berlin on 11 July 1700, four years after the Akademie der Künste or "Arts Academy", to which "Berlin Academy" may also refer.-Origins:...
in Berlin, the Russian Academy of Sciences
Russian Academy of Sciences
The Russian Academy of Sciences consists of the national academy of Russia and a network of scientific research institutes from across the Russian Federation as well as auxiliary scientific and social units like libraries, publishers and hospitals....
in Moscow. The idea came to him when in 1930 the Indian Science Congress Association
Indian Science Congress Association
Indian Science Congress Association is a premier scientific organisation of India,started in the year 1914, with Headquarters at Kolkata.. It meets annually in the first week of January every year.-Introduction:...
met in Allahabad
Allahabad
Allahabad , or Settled by God in Persian, is a major city of India and is one of the main holy cities of Hinduism. It was renamed by the Mughals from the ancient name of Prayaga , and is by some accounts the second-oldest city in India. It is located in the north Indian state of Uttar Pradesh,...
under the presidentship of C. S. Christopher. Delivering an address on the occasion, the Governor Malcolm Hailey
William Hailey, 1st Baron Hailey
William Malcolm Hailey, 1st Baron Hailey OM, GCSI, GCMG, GCIE, PC , known as Sir Malcolm Hailey between 1921 and 1936, was a British peer and administrator in British India.-Education:...
said that if a scientific body could motivate research in the university departments and steer it for public benefit, then it might become possible for the Government to offer grants for research. Saha took this hint and thanks to his effort the U.P. Academy of Sciences
National Academy of Sciences, India
The National Academy of Sciences, India is the oldest Science Academy in India. It is located in Allahabad, Uttar Pradesh...
came into existence. Despite its name, National Academy of Sciences essentially functioned as a regional body. This prompted him to envision an organisation with an all-India character and thus in 1934 he proposed the founding of an Indian Academy of Sciences. On this issue there was strong difference of opinion between him and Raman and eventually Raman announced in Bangalore
Bangalore
Bengaluru , formerly called Bengaluru is the capital of the Indian state of Karnataka. Bangalore is nicknamed the Garden City and was once called a pensioner's paradise. Located on the Deccan Plateau in the south-eastern part of Karnataka, Bangalore is India's third most populous city and...
the founding of the Indian Academy of Sciences
Indian Academy of Sciences
The Indian Academy of Sciences, Bangalore was founded by Sir C. V. Raman, and was registered as a Society on 24 April 1934. Inaugurated on 31 July 1934, it began with 65 founding fellows. The first general meeting of Fellows, held on the same day, elected Professor Raman as President, and adopted...
. This was unacceptable to Saha who continued his efforts and as a result there came into existence in 1935 the National Institute of Sciences, India with its headquarters in Calcutta
Kolkata
Kolkata , formerly known as Calcutta, is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it was the commercial capital of East India...
. The formation was formally announced on January 7 in the Senate Hall of the Calcutta University under the Chairmanship of the J.H. Hutton. L.L. Fermor was elected the first president of the Institute. The same year he also founded the Indian Science News Association at Calcutta. Its main objective was to disseminate science amongst the public.The Association started publishing its journal called Science and Culture. On receiving, a copy of the first issue of the Journal, Netaji Subhash Chandra Bose was impressed and he wrote: "The appearance of Science and Culture is to be warmly welcomed not only by those, who are interested in abstract science but also by those who are concerned with nationbuilding in practice. Whatever might have been the views of our older "Nation builders" we younger folk approach the task of nation building in a thoroughly scientific spirit and we desire to be armed with all the knowledge which modern science and culture can afford us. It is not possible however, for political workers with their unending preoccupations to glean that knowledge themselves, it is therefore, for scientists and scientific investigators to come in their rescue." Saha himself wrote more than 200 articles in Science and Culture on a wide range of topics which included: organization of scientific and industrial research, atomic energy and its industrial use, river valley development projects, planning the national economy, educational reforms and modification of Indian calendar. The journal is presently running in its 76th volume. Later, on his initiative, the headquarters of the National Institute of Sciences was shifted to Delhi May 1946 and the name was changed to the Indian National Science Academy
Indian National Science Academy
The Indian National Science Academy , New Delhi is the apex body of Indian scientists representing all branches of science & technology.-History:...
.
In 1936 Saha received a fellowship from the Carnegie Trust of the British Empire
Carnegie United Kingdom Trust
Carnegie United Kingdom Trust is a charitable foundation based in the United Kingdom, established by Scottish-born American steel magnate and philanthropist Andrew Carnegie on the model of his U.S. foundation, Carnegie Corporation of New York....
, and he went on an extended outing that took him to countries like Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....
, Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
, Jordan
Jordan
Jordan , officially the Hashemite Kingdom of Jordan , Al-Mamlaka al-Urduniyya al-Hashemiyya) is a kingdom on the East Bank of the River Jordan. The country borders Saudi Arabia to the east and south-east, Iraq to the north-east, Syria to the north and the West Bank and Israel to the west, sharing...
, Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
. At Munich he was happily reunited with Sommerfeld
Arnold Sommerfeld
Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...
. He then proceeded to London to attend the centenary celebrations of the Physics society where Max Planck
Max Planck
Max Karl Ernst Ludwig Planck, ForMemRS, was a German physicist who actualized the quantum physics, initiating a revolution in natural science and philosophy. He is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.-Life and career:Planck came...
was the chief guest. From London Saha went to Oxford
Oxford
The city of Oxford is the county town of Oxfordshire, England. The city, made prominent by its medieval university, has a population of just under 165,000, with 153,900 living within the district boundary. It lies about 50 miles north-west of London. The rivers Cherwell and Thames run through...
and spent a month in the company of Milne. Then he visited the Harvard College Observatory
Harvard College Observatory
The Harvard College Observatory is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, USA, and was founded in 1839...
in Boston
Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...
. here he met many noted scientists like Harlow Shapley
Harlow Shapley
Harlow Shapley was an American astronomer.-Career:He was born on a farm in Nashville, Missouri, and dropped out of school with only the equivalent of a fifth-grade education...
, Donald Menzel
Donald Howard Menzel
Donald Howard Menzel was one of the first theoretical astronomers and astrophysicists in the US. He discovered the physical properties of the solar chromosphere, the chemistry of stars, the atmosphere of Mars, and the nature of gaseous neblulae.-Biography:Born in Florence, Colorado in 1901 and...
, and Cecilia Payne-Gaposchkin
Cecilia Payne-Gaposchkin
-Further reading:*Rubin, Vera , "Cecilia Payne-Gaposchkin" in OUT OF THE SHADOWS: Contributions of 20th Century Women to Physics, Nina Byers and Gary Williams, ed., Cambridge University Press ....
. Moving west, he made a grand tour visiting many observatories and meeting famous people like Hubble
Edwin Hubble
Edwin Powell Hubble was an American astronomer who profoundly changed the understanding of the universe by confirming the existence of galaxies other than the Milky Way - our own galaxy...
, Walter Adams
Walter Sydney Adams
Walter Sydney Adams was an American astronomer.-Life and work:He was born in Antioch, Syria to missionary parents, and was brought to the U.S. in 1885 He graduated from Dartmouth College in 1898, then continued his education in Germany...
, and lastly Lawrence
Ernest Lawrence
Ernest Orlando Lawrence was an American physicist and Nobel Laureate, known for his invention, utilization, and improvement of the cyclotron atom-smasher beginning in 1929, based on his studies of the works of Rolf Widerøe, and his later work in uranium-isotope separation for the Manhattan Project...
in Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
. Saha and Lawrence had earlier met in Copenhagen
Copenhagen
Copenhagen is the capital and largest city of Denmark, with an urban population of 1,199,224 and a metropolitan population of 1,930,260 . With the completion of the transnational Øresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Øresund Region...
in 1927, but by now Lawrence was famous as the inventor of the cyclotron
Cyclotron
In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...
. This contact proved useful and later Lawrence helped Saha to some extent to construct a cyclotron in Calcutta. From there, he went to Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
to visit the Yerkes Observatory
Yerkes Observatory
Yerkes Observatory is an astronomical observatory operated by the University of Chicago in Williams Bay, Wisconsin. The observatory, which calls itself "the birthplace of modern astrophysics," was founded in 1897 by George Ellery Hale and financed by Charles T. Yerkes...
. Returning to Harvard, he attended the centenary celebrations of the Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
. It was then he wrote a short note entitled A Stratosphere Solar Observatory, which was published in the Harvard College Observatory Bulletin, where he explicitly suggested the observation of the solar spectrum at a height greater than 40 km, for he reckoned it was the most plausible way to get out of the atmosphere and avoiding the UV depletion that otherwise results. While in Boston, he also visited the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
, the then President of which was Karl Taylor Compton
Karl Taylor Compton
Karl Taylor Compton was a prominent American physicist and president of the Massachusetts Institute of Technology from 1930 to 1948.- The early years :...
. Returning to Europe, he attended an international conference on nuclear physics in the Niels Bohr Institute
Niels Bohr Institute
The Niels Bohr Institute is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics....
in Copenhagen. This was instrumental in shifting his focus to nuclear science later.
After his long but intellectually fulfilling tour, Saha returned to Allahabad in 1937. In 1938, he organised a symposium on "Power Supply" under the auspices of the Academy, and requested Nehru
Jawaharlal Nehru
Jawaharlal Nehru , often referred to with the epithet of Panditji, was an Indian statesman who became the first Prime Minister of independent India and became noted for his “neutralist” policies in foreign affairs. He was also one of the principal leaders of India’s independence movement in the...
to inaugurate it. Though at that point of time, Nehru and Saha shared a cordial relationship, it later turned sour, which considerably hindered the plans and propositions he wanted to advocate to employ nuclear science to public benefit.
During his time in Allahabad he rederived Dirac's
Paul Dirac
Paul Adrien Maurice Dirac, OM, FRS was an English theoretical physicist who made fundamental contributions to the early development of both quantum mechanics and quantum electrodynamics...
quantisation condition for magnetic monopole. Dirac was one of the first scientists to devote considerable attention to the study of magnetic monopole
Magnetic monopole
A magnetic monopole is a hypothetical particle in particle physics that is a magnet with only one magnetic pole . In more technical terms, a magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring...
. This led Saha to the observation that a particle could in principle have both electric charge and magnetic charge. Such a particle (hypothetical) would be called a dyon
Dyon
In physics, a dyon is a hypothetical particle in 4-dimensional theories with both electric and magnetic charges. A dyon with a zero electric charge is usually referred to as a magnetic monopole. Many grand unified theories predict the existence of both magnetic monopoles and dyons.Dyons were first...
. This quantisation condition on its charges as derived by Saha turned out to be an elegant generalisation of the principle proposed by Dirac.
Around this time, he felt constricted in Allahabad, and feeling that Calcutta would provide better opportunities to disseminate science, he returned to Calcutta in 1938.
In Calcutta
Saha returned to the Calcutta University in July 1938. He became the Palit Professor and Head of the Department of Physics. At that time Shyama Prasad MukherjeeSyama Prasad Mookerjee
Dr. Shyama Prasad Mookerjee was a minister in Jawaharlal Nehru's Cabinet as a Minister for Industry and Supply....
was the Vice Chancellor of the University and who was soon to be succeeded by Sir Mohammad Azizul Haque
Azizul Huque
Khan Bahadur Mohammad Azizul Huque was an Indian Muslim lawyer, public servant, scholar and activist.-References:...
. After joining Saha immediately got involved in organizing research in the Palit Laboratory. He also took the task of remodeling the MSc syllabus in physics. Saha later introduced a general and a special paper in nuclear physics and a general paper in quantum mechanics in 1940.
Institute of Nuclear Physics
As mentioned earlier, Saha's interest in nuclear physics was aroused during his foreign trip in 1936-37. Impressed particularly by what he saw at BerkeleyUniversity of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, he sent in 1938 his student B.D.Nag Chowdhary to Berkeley to study and work under Lawrence
Ernest Lawrence
Ernest Orlando Lawrence was an American physicist and Nobel Laureate, known for his invention, utilization, and improvement of the cyclotron atom-smasher beginning in 1929, based on his studies of the works of Rolf Widerøe, and his later work in uranium-isotope separation for the Manhattan Project...
, and learn all he could about the cyclotron
Cyclotron
In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...
. Saha was keen to have a cyclotron in the Calcutta University and used his influence with Nehru to persuade the Tatas
Tata Group
Tata Group is an Indian multinational conglomerate company headquartered in Mumbai, Maharashtra, India. Tata Group is one of the largest companies in India by market capitalization and revenue. It has interests in communications and information technology, engineering, materials, services, energy,...
to give him a grant to build one. The Tatas obliged with Rs. 60,000/- which wasn't however sufficient to construct a cyclotron. In 1941 Nag Chowdhary returned, and thanks to his efforts in America, a consignment of cyclotron parts (mainly for making the magnet) soon followed. Meanwhile America entered the war and the ship carrying the next batch of equipments (mainly vacuum pumps) was sunk by the Japanese. This was major setback, and now there was no hope of getting any parts from America; anyway, American scientists, Lawrence included, had drifted towards the Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
. The parts now all had to be made in Calcutta, and this proved to be an interminable affair. Eventually it took many years to complete (it started working after Saha passed away). Apart from this Saha also started on a modest scale some cosmic-ray observations in Darjeeling.
The event of the atom bomb dropping
Atomic bombings of Hiroshima and Nagasaki
During the final stages of World War II in 1945, the United States conducted two atomic bombings against the cities of Hiroshima and Nagasaki in Japan, the first on August 6, 1945, and the second on August 9, 1945. These two events are the only use of nuclear weapons in war to date.For six months...
on Japan made Saha further aware of the profound importance of nuclear energy. So he resolved to establish an autonomous institute under the umbrella of the university devoted exclusively to the study of nuclear science and its prospects. As a result the Saha Institute of Nuclear Physics
Saha Institute of Nuclear Physics
The Saha Institute of Nuclear Physics is an institution of basic research and training in physical and biophysical sciences located in Bidhannagar, Kolkata, India. The institute is named after the famous Indian physicist Meghnad Saha.-History:...
came into being in 1948. It was declared open by Irène Joliot-Curie
Irène Joliot-Curie
Irène Joliot-Curie was a French scientist, the daughter of Marie Skłodowska-Curie and Pierre Curie and the wife of Frédéric Joliot-Curie. Jointly with her husband, Joliot-Curie was awarded the Nobel Prize for chemistry in 1935 for their discovery of artificial radioactivity. This made the Curies...
in 1950. As per the university regulations, Saha had to retire in 1952 both from the Palit Professorship and the post of the Director of the Institute of Nuclear Physics. However he retained links with both the institutes in honorary capacity.
Indian Association for the Cultivation of Science
Right from the early thirties Saha was deeply interested in the IACSIndian Association for the Cultivation of Science
The Indian Association for the Cultivation of Science, established in July 1876 at 210 Bowbazar street, Calcutta, is a national institution for higher learning whose primary purpose is to foster high quality fundamental research in frontier disciplines of the basic sciences. Founded by Dr. Mahendra...
. In 1944 he became its Honorary Secretary, and following the death of the president in 1946, himself became its president. At that time the IACS was located in Bowbazar
Bowbazar
Bowbazar is a neighbourhood and police stationin central Kolkata, earlier known as Calcutta, in the Indian state of West Bengal...
. Following the golden era in which Raman conducted his research there, the institute sort of plodded on, and Saha was keen to inject a fresh life into it by starting several new research programmes. all this took time and money, and eventually he persuaded the Government of West Bengal
Government of West Bengal
The Government of West Bengal also known as the State Government of West Bengal, or locally as State Government, is the supreme governing authority of the Indian state of West Bengal and its 19 districts...
to shift the institute to Jadavpur
Jadavpur
Jadavpur is a southern neighbourhood of Kolkata, India. It is bounded by Dhakuria to the north, Tollygunge to the west, Santoshpur to the east and Garia to the south...
after buying ten acres of land there. Obeying the Association rules, Saha stepped down as president in 1950. Meanwhile Shanti Swaroop Bhatnagar
Shanti Swaroop Bhatnagar
Sir Shanti Swaroop Bhatnagar, OBE, FRS was a well-known Indian scientist.-Early life:Bhatnagar was born in Shahpur, now in Pakistan...
, with whom he had maintained a cordial relation since meeting him in London in 1920, suggested that it was time that the IACS had a full time director. He further insisted that the post be offered to Saha so that he could complete the reorganisation work he had started earlier. Thus in 1953, Saha became the first director of IACS, a post he held till his death in 1956.
Saha and Atomic Energy
Saha was aware of the electrifying discovery of nuclear fission by HahnOtto Hahn
Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...
and Meitner
Lise Meitner
Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...
in 1939 and the stupefying possibilities this discovery was pregnant with. Meanwhile in 1940 the British rulers in Delhi formed a Board for scientific and Industrial Research (BSIR) with Bhatnagar as the head. Saha was invited to be a member. In 1942, the Government constituted a superior body called CSIR where once again Saha was made a member.
By 1944 it became clear that the tide of fortune in the war was turning against Germany and Japan. In anticipation of victory, the British Government began to make plans for post-war reconstructions. As a part of the process, it asked the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
to send Prof. A.V. Hill to India to advise the government. Hill came and met many scientists, Saha included. He then recommended that an Indian Scientific Mission (ISM) be sent abroad to observe scientific and industrial progress and make post-war plans. The recommendation was accepted and a delegation left India in October 1944; Saha was a member of the ISM.
The tour took the mission to several countries including America. While there, Saha made enquiries about research on atomic energy but drew a blank. He did not know it right then that the Manhattan Project
Manhattan Project
The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...
was going on in full swing and atomic energy research was the most closely guarded secret. His enquiries prompted the FBI to interrogate him to gather how much he really knew about their project. However they were relieved that he knew nothing, though his knowledge and expertise on the matter astounded them. On return to India the ISM prepared an official report and submitted it to the Government; the report was drafted by Saha. In 1947 India became free and Nehru
Jawaharlal Nehru
Jawaharlal Nehru , often referred to with the epithet of Panditji, was an Indian statesman who became the first Prime Minister of independent India and became noted for his “neutralist” policies in foreign affairs. He was also one of the principal leaders of India’s independence movement in the...
became the Prime Minister
Prime Minister of India
The Prime Minister of India , as addressed to in the Constitution of India — Prime Minister for the Union, is the chief of government, head of the Council of Ministers and the leader of the majority party in parliament...
of India. Atomic energy was the new hope and as member of the BSIR, Saha had every reason to hope that he would be able to play a key role in the development of atomic energy in India. Bhabha
Homi J. Bhabha
Homi Jehangir Bhabha, FRS was an Indian nuclear physicist and the chief architect of the Indian atomic energy program...
also had similar thoughts and he too began to offer Nehru ideas on the subject. In 1948, Saha was formally asked by the Government of India at Nehru's insistence about the formation of Atomic Energy Commission
Atomic Energy Commission of India
The Atomic Energy Commission is a governing body functioning under the Department of Atomic Energy , Government of India. The DAE is under the direct charge of the Prime Minister.- History :...
which Bhabha had suggested. Saha firmly opposed the idea on the grounds that India lacked the required industrial base to augment it, and that trained manpower was not available. In his view, before launching a full-fledged atomic energy programme, the industry ought to build up first, and Nuclear physics-oriented courses should be introduced in various universities to obtain a competent manpower. He strongly advocated the French model of atomic energy development which was in fact the brainchild of his friend Frédéric Joliot-Curie
Frédéric Joliot-Curie
Jean Frédéric Joliot-Curie , born Jean Frédéric Joliot, was a French physicist and Nobel laureate.-Early years:...
. Bhabha, on the other hand, was a proponent of a much faster and more vigorous programme of development which appealed to Nehru. As a result the Atomic Energy Commission was set up in 1948 and the Atomic Energy Establishment, Trombay
Bhabha Atomic Research Centre
The Bhabha Atomic Research Centre is India's primary nuclear research facility based in Mumbai. It has a number of nuclear reactors, all of which are used for India's nuclear power and research programme.- History :...
in 1954.
Saha and calendar reform
Saha's work relating to reform of Indian calendar was very significant. Saha was the Chairman of the Calendar Reform Committee appointed by the Government of India in 1952 under the aegis of the Council of Scientific and Industrial Research. Other members of the Committee were: A. C. Banerjee, K. K. Daftari, J. S. Karandikar, Gorakh Prasad, R. V. Vaidya and N. C. Lahiri. It was Saha's effort which led to the formation of the Committee. The task before the Committee was to prepare an accurate calendar based on scientific study, which could be adopted uniformly throughout India. It was a mammoth task. The Committee had to undertake a detailed study of different calendars prevalent in different parts of the country. There were thirty different calendars. The task was further complicated by the fact that with calendar religion and local sentiments were involved. Nehru, in his preface to the Report of the Committee, which was published in 1955, wrote: "They (different calendars) represent past political divisions in the country…now that we have attained Independence, it is obviously desirable that there should be a certain uniformity in the calendar for our civic, social and other purposes and this should be done on a scientific approach to this problem." Some of the important recommendations of the Committee were:- The Saka era should be used in the unified national calendar. (The year 2002 corresponds to the Saka era of 1923-24.)
- The year should start from the day following the vernal equinox (occurs about March 21) day.
- A normal year would consist of 365 days while a leap year would have 366 days. After adding seventy-eight to the Saka era, if the sum is divisible by four, then it is a leap year. But when the same becomes a multiple of 100 it would be a leap year when it is divisible by 400, otherwise it would be a common year.
- Chaitra should be the first month of the year. From ChaitraChaitraChaitra is a month of the Hindu calendar....
to BhaadraBhaadraBhaadra or Bhadrapada is a month of the Hindu calendar. In India's national civil calendar , Bhaadra is the sixth month of the year, beginning on 23 August and ending on 22 September. Known as Purattaasi, it is the sixth month of the Tamil solar calendar...
each month would have thirty-one days and the rest to have thirty days.
Saha and river physics
Saha was deeply concerned with the recurring disastrous floods in many Indian rivers. The extensive damage caused by floods in North Bengal in 1923 prompted Acharya Prafulla Chandra Ray to organize relief operation under the aegis of North Bengal Relief Committee. Ray was able to collect a large fund from the general public for the relief work and he was assisted by Subhash Chandra Bose, Meghnad Saha and Satish Chandra Dasgupta. And it was while carrying out the relief work Saha got a first hand experience of the devastating power of floods. Saha wrote about his experience in newspapers and magazines. In his Presidential address to the Indian Science Congress in Mumbai in 1934 he drew specific attention to serious problems caused by floods. He also emphasized the need for a River Research Laboratory. Again in 1938, in his presidential address to the National Institute of SciencesIndian National Science Academy
The Indian National Science Academy , New Delhi is the apex body of Indian scientists representing all branches of science & technology.-History:...
he made this topic the theme of his discourse and highlighted the danger posed by recurrent floods in Indian rivers, particularly in the deltaic ones. After the 1923 flood, Saha witnessed two major floods in 1931 and 1935. In 1943 the flood in Bengal isolated Kolkata from rest of India and Saha wrote extensively on the issue. Saha's writings and speeches made the government realize the gravity of the situation. As a result the Damodar Valley Enquiry Committee came into being in 1943. The Committee was chaired by the Maharaja of Burdwan. Saha was also a member of the Committee. Saha presented a plan for handling the Damodar
Damodar River
Damodar River originates near Chandwa village, Palamau district, on the Chota Nagpur Plateau in the Jharkhand state in eastern India, and flows eastward for about 592 km through the states of Jharkhand and West Bengal to the estaury of the River Hooghly...
river system before the Committee. He also wrote extensively on river control based on modern science and technology. He argued that the model of Tennessee river system under the Tennessee Valley Authority
Tennessee Valley Authority
The Tennessee Valley Authority is a federally owned corporation in the United States created by congressional charter in May 1933 to provide navigation, flood control, electricity generation, fertilizer manufacturing, and economic development in the Tennessee Valley, a region particularly affected...
(TVA) in United States could be adapted to the Damodar Valley. The Central Government
Government of India
The Government of India, officially known as the Union Government, and also known as the Central Government, was established by the Constitution of India, and is the governing authority of the union of 28 states and seven union territories, collectively called the Republic of India...
appointed a technical advisory committee in 1945 under the chairmanship of Mr. H.M.Mathews. Another member of the committee was Mr.W.L.Voorduin, who had earlier served on TVA. The committee supported the claims of Saha, and at the instance of Dr. B. R. Ambedkar
B. R. Ambedkar
Bhimrao Ramji Ambedkar , popularly also known as Babasaheb, was an Indian jurist, political leader, philosopher, thinker, anthropologist, historian, orator, prolific writer, economist, scholar, editor, a revolutionary and one of the founding fathers of independent India. He was also the Chairman...
, the then member-in-charge of power and works in the Viceroy's cabinet, the Government adopted a resolution to set up a Damodar Valley Corporation
Damodar Valley Corporation
The Damodar Valley Corporation, popularly known as DVC, is the first multipurpose river valley project of independent India. The corporation came into being on July 7, 1948 by an Act of the Constituent Assembly of India . It is modelled on the Tennessee Valley Authority of the USA. Jawaharlal...
(DVC) after the model of TVA. The DVC was set up in March 1948.
Death
In early 1956, Saha developed serious health problems on account of high blood pressure. Though his doctors advised him to slow down, he continued with his work. On February 16, he had an appointment with his old friend P.C.MahalanobisPrasanta Chandra Mahalanobis
Prasanta Chandra Mahalanobis FRS was an Indian scientist and applied statistician. He is best remembered for the Mahalanobis distance, a statistical measure. He made pioneering studies in anthropometry in India...
, now a favourite of Nehru and closely associated with the Planning Commission. Enroute to the office he collapsed. He was rushed to the hospital, but he never recovered.
An estimate
Saha was of the opinion that large-scale industrialization was the only answer for improving the quality of life. He thought that India had no hope if she failed to develop science and technology. Saha wrote: "The philosophy of kindliness and service to our fellow-men was preached by all founders of great religions, and no doubt some great kings and ministers of religions in every country and at all ages tried to give effect to this (altruistic) philosophy. But the efforts were not successful, for the simple reason that the methods of production of commodities were too indifferent to yield plenty for all, which is an indispensable condition for practical altruism. We can, therefore, hold that so far as individual life is concerned, science has achieved a target aimed at by the great founders of religions in advanced countries of the world. The effects of maldistribution of wealth, due to historical causes, are being rapidly cured by introduction of social laws." Despite his patriotic dispositions, he refrained from participating in the freedom struggle. Family responsibilities compelled him to take a job, and the job he got led him to the ineffable world of science. Becoming absorbed in research he then entered what is colloquially called the ivory tower. However his withdrawal was temporary and he slowly drifted out. As he once put it: "Scientists are often accused of living in the "Ivory Tower" and not troubling their mind with realities and apart from my association with political movements in my juvenile years, I had lived in ivory tower up to 1930. But science and technology are as important for administration now-a-days as law and order. I have gradually glided into politics because I wanted to be of some use to the country in my own humble way.". In 1952 Saha was elected Member of the Parliament as an Union of Socialists and Progressives candidate from the North-West Calcutta constituency. He defeated his nearest Congress rival by an overwhelming margin. Welcoming Saha's election JBS Haldane said: "May I also be allowed to congratulate him on his recent successful reentry recently into politics. India (and Britain too) needs men who will bring some understanding of science to the government of the country. Even those who do not share his political views may rejoice that he can make his voice heard in the council of the people." He was nominated for the Nobel Prize in PhysicsNobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
four times- 1930, 1937, 1939, 1940.". It is said that the prize committee was of the opinion that one winner in a century from India was more than what Physics could tolerate.
Tributes to Saha
- "Meghnad Saha's ionization equation (c. 1920), which opened the door to stellar astrophysics" was one of the top ten achievements of 20th century Indian science [and] could be considered in the Nobel Prize class." - Jayant Vishnu Narlikar
- "The impetus given to astrophysics by Saha's work can scarcely be overestimated, as nearly all later progress in this field has been influenced by it and much of the subsequent work has the character of refinements of Saha's ideas." - S. Rosseland
- "He (Saha) was extremely simple, almost austere, in his habits and personal needs. Outwardly, he sometimes gave an impression of being remote, matter of fact, and even harsh, but once the outer shell was broken, one invariably found in him a person of extreme warmth, deep humanity, sympathy and understanding; and though almost altogether unmindful of his own personal comforts, he was extremely solicitous in the case of others. It was not in his nature to placate others. He was a man of undaunted spirit, resolute determination, untiring energy and dedication." - D. S. Kothari
- "It is a pleasure to have the opportunity of congratulating you on the occasion of your sixtieth birthday for your outstanding achievements, especially in the field of thermodynamics. As you know, I at one time had the honour of nominating you for the Nobel Prize for your work in the area..." - Arthur ComptonArthur ComptonArthur Holly Compton was an American physicist and Nobel laureate in physics for his discovery of the Compton effect. He served as Chancellor of Washington University in St. Louis from 1945 to 1953.-Early years:...
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- "I still remember with great pleasure the inspiration that I received from reading Professor Meghnad Saha's fundamental contributions to the theory of gas ionization..." - Enrico FermiEnrico FermiEnrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
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- "I well remember how, on the publication of his early and important paper on ionisation in stellar atmosphere, the late Professor Alfred Fowler drew my attention to it and emphasized its fundamental importance. And so it proved, for this paper was the stimulus to the work of Milne, R.H.Fowler, and others in subsequent years. In fact almost all work on stellar atmosphere has been based on it, either directly or indirectly. The paper provided a new method of attack and opened the way to the solution of many problems that had been puzzling." - Harold Spencer JonesHarold Spencer JonesSir Harold Spencer Jones KBE FRS was an English astronomer. Although born "Jones", his surname became "Spencer Jones"....
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- "I have known and admired him for many years. Indeed, I shall never forget the intellectual thrill I derived from learning about "Saha's ionisation equation" in my early days as a graduate student...." - Ernest LawrenceErnest LawrenceErnest Orlando Lawrence was an American physicist and Nobel Laureate, known for his invention, utilization, and improvement of the cyclotron atom-smasher beginning in 1929, based on his studies of the works of Rolf Widerøe, and his later work in uranium-isotope separation for the Manhattan Project...
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- "The Harvard Observatory owes much to Professor Meghnad Saha. His pioneer work thirty years ago on temperature ionisations in sun and stars inspired the activities of British scientists who in turn inspired the work here at Harvard of Mrs. Cecilia Payne-Gaposchkin, Donald M. Menzel and Frank Hogg; their work established modern astrophysics in Harvard." - Harlow ShapleyHarlow ShapleyHarlow Shapley was an American astronomer.-Career:He was born on a farm in Nashville, Missouri, and dropped out of school with only the equivalent of a fifth-grade education...
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- "Many years ago when I was a graduate at California, I was working on some things in connection with the ionisation of the alkali metals - a problem which I never succeeded in finishing. In the course of this work I read with great interest your very important publication of that time on the ionisation as it affected the spectra of the star. It was in fact one of the first scientific papers which I read with very great care as a graduate student...I greatly admired this publication and it has been referred to over and over again in the years since..." - Harold UreyHarold UreyHarold Clayton Urey was an American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934...
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Further reading
- Obituary - The Observatory 76 (1956) 40
- Obituary - Proceedings of the Astronomical Society of the Pacific 68 (1956) 282
External links
- Biography
- Chitra Roy on her father
- Biography
- ScienceWorld: Saha Equation
- http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&qform=AST&arxiv_sel=astro-ph&arxiv_sel=cond-mat&arxiv_sel=cs&arxiv_sel=gr-qc&arxiv_sel=hep-ex&arxiv_sel=hep-lat&arxiv_sel=hep-ph&arxiv_sel=hep-th&arxiv_sel=math&arxiv_sel=math-ph&arxiv_sel=nlin&arxiv_sel=nucl-ex&arxiv_sel=nucl-th&arxiv_sel=physics&arxiv_sel=quant-ph&arxiv_sel=q-bio&sim_query=YES&ned_query=YES&aut_logic=OR&obj_logic=OR&author=Saha%2C+M&object=&start_mon=&start_year=&end_mon=&end_year=&ttl_logic=OR&title=&txt_logic=OR&text=&nr_to_return=100&start_nr=1&jou_pick=ALL&ref_stems=&data_and=ALL&group_and=ALL&start_entry_day=&start_entry_mon=&start_entry_year=&end_entry_day=&end_entry_mon=&end_entry_year=&min_score=&sort=SCORE&data_type=SHORT&aut_syn=YES&ttl_syn=YES&txt_syn=YES&aut_wt=1.0&obj_wt=1.0&ttl_wt=0.3&txt_wt=3.0&aut_wgt=YES&obj_wgt=YES&ttl_wgt=YES&txt_wgt=YES&ttl_sco=YES&txt_sco=YES&version=1List of M. N. Saha's papers]