Homi Jehangir Bhabha, FRS (30 October 1909 – 24 January  1966) was an Indian nuclear physicist and the chief  architect of the Indian atomic energy program. He was also  responsible for the establishment of two well-known  research institutions, namely the Tata Institute of  Fundamental Research (TIFR), and the Atomic Energy  Establishment at Trombay (which after Bhabha's death was  renamed as the Bhabha Atomic Research Centre (BARC)). As a scientist, he is remembered for deriving a correct  expression for the probability of scattering positrons by  electrons, a process now known as Bhabha scattering.

Bhabha was born into a wealthy and prominent Parsi family,  through which he was related to Dinshaw Maneckji Petit,  Muhammad Ali Jinnah and Dorab Tata. He received his early  education at Bombay's Cathedral Grammar School and entered  Elphinstone College at age 15 after passing his Senior  Cambridge Examination with Honors. He then attended the  Royal Institute of Science until 1927 before joining Caius  College of Cambridge University. This was due to the  insistence of his father and his uncle Dorab Tata, who  planned for Bhabha to obtain an engineering degree from  Cambridge and then return to India, where he would join  the Tata Iron and Steel Company in Jamshedpur.

• Higher education and research at Cambridge

 At Cambridge Bhabha's interests gradually shifted to  theoretical physics. In 1928 Bhabha in a letter to his  father wrote:

“ I seriously say to you that business or job as an  engineer is not the thing for me. It is totally foreign to  my nature and radically opposed to my temperament and  opinions. Physics is my line. I know I shall do great  things here. For, each man can do best and excel in only  that thing of which he is passionately fond, in which he  believes, as I do, that he has the ability to do it, that  he is in fact born and destined to do it... I am burning  with a desire to do physics. I will and must do it  sometime. It is my only ambition. I have no desire to be a  `successful' man or the head of a big firm. There are  intelligent people who like that and let them do it... It  is no use saying to Beethoven `You must be a scientist for  it is great thing ' when he did not care two hoots for  science; or to Socrates `Be an engineer; it is work of  intelligent man'. It is not in the nature of things. I  therefore earnestly implore you to let me do physics.

Bhabha's father understood his son's predicament, and he  agreed to finance his studies in mathematics provided that  he obtain first class on his Mechanical Sciences Tripos. 

Bhabha took the Tripos in June 1930 and passed with first  class. He then embarked on his mathematical studies under  Paul Dirac to complete the Mathematics Tripos. Meanwhile,  he worked at the Cavendish Laboratory while working  towards his doctorate in theoretical physics under R. H.  Fowler. At the time, the laboratory was the center of a  number of scientific breakthroughs. James Chadwick had  discovered the neutron, John Cockcroft and Ernest Walton  transmuted lithium with high-energy protons, and Patrick  Blackett and Giuseppe Occhialini used cloud chambers to  demonstrate the production of electron pairs and showers  by gamma radiation. During the 1931–1932 academic year,  Bhabha was awarded the Salomons Studentship in  Engineering. In 1932, he obtained first class on his  Mathematical Tripos and was awarded the Rouse Ball  traveling studentship in mathematics. With the  studentship, he worked with Wolfgang Pauli in Zürich,  Enrico Fermi in Rome and Hans Kramers in Utrecht.

• Research in theoretical physics

In January 1933, Bhabha published his first scientific  paper, "The Absorption of Cosmic radition. In the  publication, Bhabha offered an explanation of the  absorption features and electron shower production in  cosmic rays.The paper helped him win the Isaac Newton

Studentship in 1934, which he held for the next three  years. The following year, he completed his doctoral  studies in theoretical physics under Ralph H. Fowler.  During his studentship, he split his time working at  Cambridge and with Niels Bohr in Copenhagen. In 1935,  Bhabha published a paper in the Proceedings of the Royal  Society, Series A, in which performed the first  calculation to determine the cross section of electron- positron scattering. Electron-positron scattering was  later named Bhabha scattering, in honor of his  contributions in the field.

In 1936, the two published a paper, "The Passage of Fast  Electrons and the Theory of Cosmic Showers" in the  Proceedings of the Royal Society, Series A, in which they  used their theory to describe how primary cosmic rays from  outer space interact with the upper atmosphere to produce  particles observed at the ground level. Bhabha and Heitler  then made numerical estimates of the number of electrons  in the cascade process at different altitudes for  different electron initiation energies. The calculations  agreed with the experimental observations of cosmic ray  showers made by Bruno Rossi and Pierre Victor Auger a few  years before. Bhabha later concluded that observations of  the properties of such particles would lead to the  straightforward experimental verification of Albert  Einstein's theory of relativity. In 1937, Bhabha was  awarded the Senior Studentship of the 1851 Exhibition,  which helped him continue his work at Cambridge until the  outbreak of World War II in 1939.

• Return to India

In September 1939, Bhabha was in India for a brief holiday  when World War II broke out, and he decided not to return  to England for the time being. He accepted an offer to  serve as the Reader in the Physics Department of the  Indian Institute of Science, then headed by renowned 

physicist C. V. Raman. He received a special research  grant from the Sir Dorab Tata Trust, which he used to  establish the Cosmic Ray Research Unit at the institute.  Bhabha selected a few students, including Harish-Chandra,  to work with him. Later, on 20 March 1941, he was elected  a Fellow of the Royal Society .

• TIFR and BARC

When Bhabha was working at the Indian Institute of  Science, there was no institute in India which had the  necessary facilities for original work in nuclear physics,  cosmic rays, high energy physics, and other frontiers of  knowledge in physics. This prompted him to send a proposal  in March 1944 to the Sir Dorab J. Tata Trust for  establishing 'a vigorous school of research in fundamental  physics'. In his proposal he wrote :“There is at the moment in India no big school of  research in the fundamental problems of physics, both  theoretical and experimental. There are, however,  scattered all over India competent workers who are not  doing as good work as they would do if brought together in  one place under proper direction. It is absolutely in the  interest of India to have a vigorous school of research in  fundamental physics, for such a school forms the spearhead  of research not only in less advanced branches of physics but also in problems of immediate practical application in  industry. If much of the applied research done in India  today is disappointing or of very inferior quality it is  entirely due to the absence of sufficient number of  outstanding pure research workers who would set the  standard of good research and act on the directing boards  in an advisory capacity ... Moreover, when nuclear energy  has been successfully applied for power production in say  a couple of decades from now, India will not have to look  abroad for its experts but will find them ready at hand. I  do not think that anyone acquainted with scientific  development in other countries would deny the need in  India for such a school as I propose.

The subjects on which research and advanced teaching would  be done would be theoretical physics, especially on  fundamental problems and with special reference to cosmic  rays and nuclear physics, and experimental research on  cosmic rays. It is neither possible nor desirable to  separate nuclear physics from cosmic rays since the two  are closely connected theoretically.”

The trustees of Sir Dorab J. Tata Trust decided to accept  Bhabha's proposal and financial responsibility for  starting the Institute in April 1944. Bombay was chosen as  the location for the prosed Institute as the Government of  Bombay showed interest in becoming a joint founder of the  proposed institute. The institute, named Tata Institute of  Fundamental Research, was inaugurated in 1945 in 540  square meters of hired space in an existing building. In  1948 the Institute was moved into the old buildings of the  Royal Yacht club.

When Bhabha realized that technology development for the  atomic energy programme could no longer be carried out  within TIFR he proposed to the government to build a new  laboratory entirely devoted to this purpose. For this  purpose, 1200 acres of land was acquired at Trombay from  the Bombay Government. Thus the Atomic Energy  Establishment Trombay (AEET) started functioning in 1954.  The same year the Department of Atomic Energy (DAE) was  also established.

• Death and legacy

He died when Air India Flight 101 crashed near Mont Blanc  on January 24, 1966. The Atomic Energy Establishment  Trombay (AEET) was renamed as Bhabha Atomic Research  Centre in his honour. In addition to being an able  scientist and administrator, Bhabha was also a painter and  a classical music and opera enthusiast, besides being an  amateur botanist.

Bhabha also encouraged research in electronics, space  science, radio astronomy and microbiology. The famed radio telescope at Ooty, India was his  initiative, and it became a reality in 1970. The Homi  Bhabha Fellowship Council has been giving the Homi Bhabha  Fellowships since 1967 Other noted institutions in his  name are the Homi Bhabha National Institute, an Indian  deemed university and the Homi Bhabha Centre for Science  Education, Mumbai, India.