BHABHA, HOMI JEHANGIR

(b. Bombay, India, 30 October 1909; d. Mont Blanc, France, 24 January 1966),

physics.

Bhabha was the son of Jehangir Bhabha, a barrister, and the former Meherbai Framji Panday, both members of the small but prosperous and influential Parsi community of Bombay. He was also connected to the Tata family through the marriage of his paternal aunt, Meherbai, to Sir Dorab Tata. He attended Cathedral High School in Bombay from 1916 to 1925, then began preparations for the Senior Cambridge Examination at Elphinstone College and the Royal Institute of Science in that city. In 1927 Bhabha entered Gonville and Caius College, Cambridge, where he studied mechanical engineering with the expectation of an industrial career in the Tata family’s business empire. Bhabha preferred mathematics and theoretical physics, however; and after receiving first-class marks in 1930, he was accepted as a research student at the Cavendish Laboratory, still directed by Ernest Rutherford. His activities were centered there until 1939. He also traveled extensively on the Continent, however, particularly between 1934 and 1936, spending time with Enrico Fermi’s group in Rome, with Wolfgang Pauli’s group in Zurich, and at Niels Bohr’s institute in Copenhagen, He was awarded the Ph.D. from Cambridge in 1935.

Brapha was in India on a holiday at the outbreak of World War II in September 1939. Since he was unable to return to England, he accepted a readership created for him at the Indian Institute of Science at Bangalore, which owed its existence in part to the munificence of the Tata family. C. V. Raman was still a member of the physics department, and is said to have had a significant influence on Bhabha’s work there. Bhabha was promoted to professor of cosmic ray physics in 1941, the same year in which he was elected fellow of the Royal Society. It is M. G. K. Menon’s opinion that Bhabha found his mission in life during his years at Bangalore, since it was there that he became aware of the role he could play in the development of moden science and technology in India. In March 1944 he proposed to the chairman of the Sir Dorab Tata Trust the establishment of an institution that would be devoted to advanced research and teaching in physics, particularly cosmic ray and nuclear physics, and mathematics. The institute, named the Tata Institute for Fundamental Research, was founded in June 1945 at the Indian Institute of Science in Bangalore, with Bhabha as its director, In December 1945 it was relocated in Bombay.

From its inception the Tata Institute was conceived by Bhabha to be not only a first-rate center for basic research, but also an incubator where viable new types of industrial enterprises could be nurtured. His vigorous advocacy of a nuclear-powered electrical system for India led to the creation of the Indian Atomic Energy Commission in 1948 and to Bhabha’s appointment as its chairman, Most of the commission’s early research and development activities were carried out at the Tata Institute. When the commission was reorganized in 1954 as the Department of Atomic Energy, Bhabha was named its secretary with direct responsibility to the prime minister. During that same year he was also appointed director of the Atomic Energy Research Center, which was being constructed at Trombay, a northern suburb of Bombay,

Bhabha was a staunch advocate of international cooperation in science, and entered into agreements with Canada, Great Britain, France, and the United States for assistance in developing the Indian atomic energy program. He was the unanimous choice of the scientific advisory committee to the secretary-general of the United Nations for the post of president of the First International Conference on Peaceful Uses of Atomic Energy, held at Geneva in 1955. He became a governor of the International Atomic Energy Agency at Vienna, established as a result of that conference, as well as a member of the scientific advisory committee to its secretary-general. On 24 January 1966 an airplane carrying him to a meeting of that committee crashed on Mont Blanc, A year after his death the Trombay Center was reded Seated as the Bhabha Atomic Research Center.

In 1966 Werner Heitler stated that the twenty papers Bhabha had published prior to his return to India in 1939 were sufficient in themselves to have earned him a lasting reputation as a theoretical physicist. Bhabha continued to publish prolifically until he became secretary of the Department of Atomic Energy, Of the sixty-six papers he wrote alone or with others between 1933 and 1954, sixty-two are either original contributions to theoretical physics or review articles on the current state of cosmic ray or nuclear physics, He published no papers in pure physics after 1954, although he invariably participated in the Wednesday afternoon theoretical physics seminar at the Tata Institute whenever he was in Bombay.

Bhabha’s Cavendish period coincided with the early years of activity in a field that later emerged as high-energy physics. In 1932 John Cockcroft and E. T. S, Walton achieved the first disintegrations of nuclei with electrostatically accelerated particles. In the same year the positive electron, or positron, was discovered by Carl Anderson at the California Institute of Technology, thus providing spectacular confirmation of the relativistic electron theory of Paul Dirac, Bhabha’s tutor in mathematics at Caius College. Shortly afterward Patrick M. S. Blackett and G. P. S. Occhialini, working at the Cavendish, used cloud chamber techniques to demonstrate that electron-positron pairs are produced by the interaction of high-energy gamma rays with matter. They also showed that primary gamma rays of sufficiently high energy can produce secondary electrons and positrons that interact with matter to produce additional gamma rays. The latter can then interact with matter to yield additional electron-positron pairs. Thus a primary gamma ray can dissipate its energy in the form of a shower.

The interpretation of shower phenomena required the development of methods for the detailed analysis of the successive interactions of gamma rays, electrons, and positrons with the atoms constituting bulk matter. Bhabha’s first paper, published in 1933, was concerned with the absorption of high-energy gamma rays by matter. In 1935 he derived a correct expression for the cross section (probability) of the scattering of positrons by electrons, a process subsequently known as Bhabha scattering.

During the 1930’s cosmic rays provided the only source of high-energy particles. Thus Bhabha’s research inevitably turned to the phenomenological interpretation of cosmic ray interactions. In 1937 he wrote a classic paper with Heitler on the theory of electron- and gamma-ray-induced cosmic ray showers. This paper also demonstrated that the very penetrating component of cosmic ray showers observed at ground level and underground could not be composed of electrons. The particles were later (1946) identified as muons (mu-mesons).

James Chadwick’s discovery of the neutron in 1932 led inevitably to speculations about the character of the force that binds protons and neutrons into stable nuclei. In 1935 Hideki Yukawa proposed a model that vested the nuclear force in the exchange of an unstable particle between the nuclear constituents. These hypothetical particles, with about one-sixth the proton mass, became known as mesatrons, and later as mesons. Yukawa’s model assumed scalar mesons; that is, mesons with zero intrinsic angular momentum, or spin. Bhabha, among others, developed an exchange model for vector mesons with one unit of spin, in which the unit is Planck’s constant, h divided by 2π. Yukawa’s meson, now called the pimeson, was first positively identified by Occhialini and Cecil F. Powell in a series of cosmic ray experiments in 1947. It soon became evident, however, that this particular meson could not account for all details of the nuclear interaction. With the discovery of several types of heavier mesons of both the scalar and vector types in the early 1960’s. Bhabha’s conviction that the meson exchange force need not be as simple as Yukawa had first hypothesized was in part vindicated.

Yukawa’s meson theory made it clear that cosmic ray phenomena could not be described exclusively in terms of electromagnetic interactions, as had been tacitly assumed prior to 1935. During the late 1930s a good deal of Bhabha’s theoretical work dealt with nuclear forces and cosmic rays, and reflected the complications that had been introduced by meson theory. Bhabha was also the first to point out, in a 1938 letter to Nature, that the lifetimes of fast, unstable cosmic ray particles would be increased because of the time-dilation effect that follows as a consequence of Einstein’s special theory of relativity. The verification of this effect by means of cosmic ray experiments is often cited as one of the most straightforward pieces of experimental evidence supporting special relativity.

Bhabha’s published contributions to phenomenological cosmic ray theory continued through 1954. According to Menon, however, Bhabha derived his greatest sense of intellectual achievement from a series of highly abstract papers published during his years at Bangalore and his first years at the Tata Institute. These dealt with the classical theory of point particles moving in a general field, and with relativistic wave equations for particles having half-odd integral intrinsic spins greater than one-half. To Menon, these abstract papers exhibited Bhabha’s fascination with the aesthetic beauty of exact mathematical solutions.

Bhabha had a deep involvement with both music and art. As a boy he had learned to appreciate classical Western music by listening to the extensive record collections of his grandfather and aunt, and extended that appreciation during his years in Europe. According to Menon, he began to immerse himself in classical Indian music only during his years in Bangalore. Bhabha also became a serious artist while a student at Cambridge. Over the years the subject matter of his paintings changed from figures to landscapes and then to abstracts. Later, when he had less time for painting, he turned to figure drawing in charcoal and pencil. Bhabha became a major patron of contemporary art in India, purchasing paintings and sculpture for himself, for the Tata Institute, and for the Trombay Atomic Research Center.

The similarities between Bhabha and Jawaharlal Nehru have frequently been noted. Both were born into upper-class, Westernized families; both spent long periods in England during their formative years and traveled extensively in Europe; both discovered and came to appreciate Indian culture after they had learned to feel comfortable with high European culture; both became convinced at an early stage of the importance of science and technology for the development of independent India. The fact that Bhabha was able to convince the prime minister within a year of independence that the government should embark on an atomic energy program and that he, Bhabha, should have undisputed authority over its development was no doubt due in large part to the similarities in their backgrounds and aspirations. Nehru came to rely heavily on Bhabha’s scientific advice. Indeed, by 1952 they met weekly whenever both were in India. Bhabha’s success in combining in his own person both the scientific and the political direction of the Indian atomic energy program was so persuasive that his successor as secretary of the department of atomic energy, Vikram Sarabhai, was also a physicist who had spent his early professional years in pure research, and had subsequently become a junior colleague of Bhabha.

Bhabha never married. He was president of the Indian National Science Congress in 1951, and in 1954 was awarded the Padma Bhushan by the government of India. He was elected a foreign associate of the U.S. National Academy of Science in 1963.

BIBLIOGRAPHY

I. Original Works. Bhabha’s more significant scientific writing include “Zur Absorption der Hohenstrahlung,” in Zeitschrift fur Physik,83 (1933), “Passage of very fast protons Through Matter,” in nature, 134 (1934), “Electron-position Scattering,” in proceedings of the royal society, A154 (19350, 195; “passage of fast Electron through Matter,” in nature, 138 (1936), 401, written with W. Heitler; “Passage of Fast Electrons and the Theory of Cosmic Shows,” in proceedings of the royal society. A159 (1937), 432, written with W.Heitler: “Penatrating Component of Cosmic Radiation,” ibid., A164 (1938), 257; “Theory of Heavy Electrons and Nuclear Fores,” ibid., A166 (1939, 384; “Elementary Heavy particles with Any Integral Charge,” in proceeding of the Indian Academy of sciences,aii (1940), 347, 468; “General Classical Theory of Spinning Particles in a Maxwell Field,” in proceeding of Royal society, 178 (1941), 273, written with H. C. Corben;“General Classical Theory of Spinning Partical in a Meson Field.” ibid., 314; “On the Theory of Point Particles” ibid., A183 (1944) 134 written with Harish Chandra; “Relativitic Equations for partial of Arbitary spin ,” “in current science (Bangalore), 14 (1945), 89; and “On the Fields and Equations of Motion of point -particles,” in proceedings of the royal society ,A185 (1946), 250, written with Harish- chandra.

II. Secondary Literature. See Sir John Cockcroft. “Homi Jehangir Bhabha,” in proceedings of the Royal Institution of Great Britain , pt. 1, 188 (1966 ,449; M. G. K. Menon “Homi Jehangir Bhabha ,” in proceeding of the Roy institutions of Great Penney ,“Homi Jehangir Bhabha,” in biographical Memoris of Fellows of the Royal Society 13 (1967), 35-52.

William A. Blanpied

Homi Jehangir Bhabha

The Indian atomic scientist Homi Jehangir Bhabha (1909-1966) made contributions of fundamental importance to quantum theory. He was the first chairman of India's Atomic Energy Commission.

Homi Jehangir Bhabha was born on Oct. 30, 1909, in Bombay, where his family were wealthy Parsis, the tiny but influential Zoroastrian sect of western India. After graduating from Elphinstone College and the Royal Institute of Science in Bombay, he went to Cambridge University, receiving a doctorate in 1934. During this period he worked with Niels Bohr on the studies that led to quantum theory. Later, Bhabha worked with Walter Heitler on the cascade theory of electron showers, which was of great importance for the understanding of cosmic radiation, and he also did significant work in identifying the meson. Bhabha received early recognition for his work, being elected to the Royal Society in 1941.

Bhabha returned to India in 1940, doing research on cosmic rays at the Indian Institute of Science at Bangalore. In 1945 he became director of the Tata Institute of Fundamental Research in Bombay, which he had been instrumental in founding. He was a skilled administrator, and through his scientific eminence, wealth, and friendship with Prime Minister Jawaharlal Nehru, he gained a dominant position in the allocation of India's scientific resources.

Bhabha became the first chairman of the Atomic Energy Commission of India in 1948. Under his guidance Indian scientists worked on the development of atomic energy, and the first atomic reactor in Asia went into operation at Trombay, Bombay, in 1956. Bhabha was chairman of the first United Nations Conference on the Peaceful Uses of Atomic Energy, held in Geneva in 1955. At that time he predicted that man would find a way to limitless industrial power through the control of nuclear fusion. He advocated international control of nuclear energy and the outlawing of atomic bombs by all countries. Bhabha was strongly opposed to the production of an atomic bomb by India, even though the country had the resources to build one, arguing that nuclear energy should be used instead to relieve the poverty and misery of India's people. He refused a post in the Indian Cabinet but was scientific adviser to Nehru and to his successor, Lal Bahadur Shastri.

Bhabha received many honorary degrees from Indian and foreign universities and was a member of numerous scientific societies, including the National Academy of Sciences in the United States. He was the author of many articles on quantum theory and cosmic rays. Bhabha was killed, at the height of his prestige in the Indian scientific and political world, in an airplane crash in Switzerland on Jan. 24, 1966.

Further Reading

Although there is no book-length biography of Bhabha, there is an excellent account of his life and work in Jagit Singh, Some Eminent Indian Scientists (1966). For readers interested in Indian science generally, the Press Institute of India, Science in India's Future (1969), is an anthology of articles.

Additional Sources

Anderson, Robert S., Building scientific institutions in India: Saha and Bhabha, Montreal: Centre for Developing-Area Studies, McGill University, 1975. □