G. Rajasekaran

Homi Jahangir Bhabha

 

 

                     

                              
 
Early Life

Homi Jahangir Bhabha was born on 30 October 1909 in Bombay in a Parsi family. When he was 15, he passed the Senior Cambridge examination and
did his higher education in Elphinston College and then Royal Institution of Science, both in Bombay. In 1927, when he was 18, he was sent to Cambridge University, England.

​

His father was working as Senior Engineer at the Tata Company. After his higher education Homi's father wanted him to work in commerce or engineering. But Homi wrote to his father that his mind was in Science, particularly Physics and that he wanted to become a scientist. Father's reply was: "If you pass Mechanical Tripos, you can do as you wish." Homi Bhabha passed not only Mechanical Tripos but also Mathematical Tripos and entered Physics Department.
 
Some lines from the letter that Bhabha wrote to his father in 1928:

​

​

"Commerce or Engineering is not my way. They are quite far away from my nature. Physics alone is my way."

I know that I will achieve much in that. Everybody must go along the way in which he has a passionate involvement and in which he can achieve total success. Everybody must follow the path which he believes is ordained for him. My success will entirely depend on what I do and will have nothing to do with the opinion of others."

​

What is the reason for my quoting these lines?

​

Even today, many students who are attracted by Science enter engineering or medicine because of the compulsion of their parents. Later one sees their  disappointment since they left Science which they liked. Students and their parents must ponder how Homi Bhabha succeeded in clinging to his aim with
steadfastness.

​

Bhabha's discoveries

​

 

1. Bhabha scattering

2. Cosmic ray Showers and Bhabha-Heitler Theory

3. Discovery of the Muon

4. Dilatation of particle life-time

5. Bhabha's equations

​

We shall explain each of these and point out how they have become part of today's basic research.

​

1. Bhabha scattering

When an electron and a positron collide, they come out in different directions. This is called Bhabha scattering.

​

Paul Adrien Maurice Dirac discovered the quantum mechanical equation for the electron in the year 1928. This was an important discovery. For, this equation
succeeded in combining relativity and quantum mechanics which were the two great revolutions of the twentieth century. 

​

Through his equation Dirac discovered that there is an antiparticle for the electron. It is called the positron. Both electron and positron have the same
mass. Their electric charges, although of same magnitude, are of opposite sign. In the same way, every elementary particle has its antiparticle. This is now
known as an important consequence of relativistic quantum mechanics.

​

When an electron and positron collide at high energy, what are the directions which the final electron and positron take? Bhabha calculated this correctly
using Dirac equation. Bhabha's result is regarded as an important part of Quantum Electrodynamics (QED) and all students of QED learn it. 

​

Further, the formula derived by Bhabha has become a very useful tool in High energy Physics Laboratories. When electrons and positrons collide at high energy,
many new particles are produced. Recently, many new particles were discovered through this reaction only. Electron-positron collision is a research taking
place in many laboratories. Scientists use the Bhabha scattering formula to determine the total number of electrons and positrons that collide.

​

2. Cosmic Ray Shower and Bhabha-Heitler Theory

Cosmic rays were discovered in 1900. They are mostly high-energy protons which are generated in many parts of the Universe and are running everywhere. They fall on the Earth also. Since Earth is surrounded by atmosphere, these protons collide on the nitrogen or oxygen nuclei and create many kinds of new particles. All
this fall on the surface of the Earth. This is called cosmic ray shower. Many elementary particles were discovered from cosmic ray showers.

​

How energetic are the electrons produced in cosmic ray showers, how far can they penetrate in lead or iron - all these were studied. In this research,  electromagnetic cascade or electromagnetic shower was discovered. This electromagnetic shower results from the following processes:

​

1. When an electron collides on a nucleus, a photon may be emitted. 

2. When a photon collides on a nucleus, an electron-positron pair may be produced. 

3. When an electron and positron collide with each other, two photons may be produced.

​

These three processes occurring sequentially will produce the electromagnetic shower. In 1936, Bhabha and the Swiss scientist Walter Heitler worked out the full details of the electromagnetic shower. Bhabha-Heitler theory was used in all subsequent cosmic 
ray research.

​

3. Discovery of the Muon

An important puzzle about cosmic rays was their penetrating power. Normally a cosmic-ray electron penetrates 10 to 15 cm of lead. But it was found that in cosmic rays there were particles that were able to penetrate one metre of lead. Bhabha, using his Bhabha-Heitler theory performed detailed analysis of all cosmic ray data and concluded that the penetrating particles were new particles that were about 100 times heavier than electrons. He called them "Heavy Electrons".

​

Later, Carl Anderson in California Institute of Technology photographed the paths of these particles in the particle detector called cloud chamber. These became
known as Muons.

​

In today's basic research, the muon has turned out to be an important particle. The Universe is made of matter. How did antimatter disappear? Answer to this puzzle is hidden in the muon. In 1974, the tau particle which is even heavier than muon was discovered. Among elementary particles, there exist 3 families: electron family, muon family and tao family. Two Japanese physicists discovered that only if 3 families exist the above puzzle can be resolved. They made this discovery even before the three families were found experimentally. They were awarded the Nobel Prize in 2008.

​

So it will be clear how important to basic physics is the muon discovered in cosmic rays.
 



   
4.Dilatation of particle life-time

According to Einstein's Theory of Relativity, time is not absolute; it is relative. Time will change according to speed. If speed increases, time will increase. But to
see this increase, the speed must be very high. Only if we travel with a speed very near the speed of light, we can see this increase in time period.

​

Particles like muon decay and hence they all have a life-time. After that most of them decay. This life-time depends on the speed of the particle, according to the
theory of relativity. Particles travelling with high speed live for very long. It was Homi Bhabha who discovered this important truth and explained it. Only because
of this dilatation of life-time, muons that are produced by cosmic rays in the atmosphere 10 or 20 km high, manage to reach the surface of the Earth without decay.

​

Einstein's relativity theory is taught to college students. To explain the important consequence of relativity, namely that time is not absolute, some ununderstandable exotic examples are given. Easily understandable particle life time dilatation discovered by Bhabha is not taught!
 
5.Bhabha equations

We mentioned about Dirac's relativistic equation already. Dirac equation is applicable for spin 1/2 particles like the electron. Bhabha discovered the relativistic equations for particles of higher spins such as 1, 3/2 ... They are called Bhabha equations. After that many scientists were involved in finding more equations for higher-spin particles and this research continues.

​

Bhabha's discoveries so far were enough to make him a great scientist. But, destiny had other plans for Bhabha. Rest of the essay is about that.

​

Creation of scientific institutions

World War II started in 1939. Bhabha who had come to India on vacation could not return to England. It is at that time that Bhabha realized what was his true destiny. With the help of Tata Trust and the Government of India, he created two very different institutions. One was Tata Institute of Fundamental Research at Bombay and the other was the Department of Atomic Energy and its research centre called Atomic Research Establishment, Trombay (which was renamed as Bhabha Atomic Research Centre after his passing away).

​

In August 1943, Bhabha wrote a letter to JRD Tata on the possibilities of scientific research in India. He emphasized that if India has to progress, large investments in fundamental research was necessary. This research will not yield any economic profit immediately, but it is very important for the progress of the country. He said:

​

"Any knowledge about the Universe will not remain useless. One day, it will be definitely used for the welfare of humans. Further, any new knowledge will affect the scientific knowledge so far collected, in a small or big way."

​

Encouraged by the favourable response of JRD Tata, on 12 March 1944, Bhabha wrote a letter to Sir Sohrab Saklatwala who was the Chairman of Sir Dorab Tata Trust, proposing the creation of a research institute. He said:

​

"When the world starts using atomic energy successfully in about 20 years, India will not have to search for experts in foreign countries. They will be in Indian institutions."

​

This letter was written by Bhabha from Bangalore in March 1944. This was one year and five months before atomic bombs were dropped on Hiroshima and Nagasaki. Research on atomic bomb was going on in USA secretively. What Bhabha knew was only that nuclear fission has been discovered in Germany. Homi Bhabha dreamed about the peaceful utilization of nuclear energy even before USA made the atomic bomb. As early as 1944, Bhabha realized the importance
of atomic energy for the economic progress of India.

​

One can see Bhabha's vision for the future in this letter. Some more lines from that:

​

       
 

​

That seed flowered into the Tata Institute of Fundamental Research, with the blessings of the First Prime Minister of India, Jawaharlal Nehru and the help of JRD Tata. As Bhabha used to say often, it served as the cradle of the Atomic Energy plan in India.

​

Tata Institute of Fundamental Research (TIFR)

TIFR, founded by Homi Bhabha in 1945, soon developed into the top research institute of India. It started with Mathematics, Theoretical Physics, Cosmic Rays, Nuclear physics, Electronics and Computer Science and expanded to include Astronomy, Biology and Chemistry. Now it is doing front-line research in all fields of Science. 

​

Bhabha brought from USA or Europe top scientists from every field and made them start a research department in that field. K Chandrasekharan who created a World-class School of Mathematics, Bernard Peters and MGK Menon who created the cosmic ray department, Govind Swarup who constructed the Ooty Radio Telescope and the Giant Metre Wave Radio Telescope near Pune and Obaid Siddiqui who started the Molecular Biology department were brought by Bhabha.

​

​

​

                        
 

 

Some achievements of TIFR
 

• World-class School of Mathematics: After education in Loyola or Vivekananda College in Madras, CS Seshadri, MS Narasimhan and MS Raghunathan joined TIFR and did top-level research in Mathematics and became FRS.

• One of the biggest radio telescopes in the world, the GMRT was set up near Pune. 

• The very first detection of neutrinos from cosmic rays in the underground laboratory of TIFR in the Kolar Gold Fields in the year 1965.

• The first indigenous computer TIFRAC.

​

The achievements of TIFR are not confined to the above. Many institutions of fundamental research founded by others after India got independence now are administered by the Department of Atomic Energy and their functioning is modelled after TIFR. Saha Institute of Nuclear Physics, Kolkata, Institute of Mathematical Sciences, Chennai, Institute of Physics, Bhubaneswar and Harishchandra Research Institute, Allahabad are these.

​

Further, research institutes for Radio Astronomy, Molecular Biology and Applied Mathematics were set up in Bangalore and Pune and function as parts of TIFR. The International Centre for Theoretical Sciences at Bangalore is also a part of TIFR. A new campus for TIFR has been started in Hyderabad.

​

Bhabha and Neutrinos

Bhabha suggested a research idea to Sreekantan in 1950. It was to detect cosmic ray particles underground by going into the Kolar Gold Fields. At a depth of 1 or 2 km, are there any other penetrating particles apart from muons? This was the question.

​

Sreekantan, Ramana Murthy and Naranan started this research following Bhabha's suggestion. This experiment continued for more than twenty years. The flux of the muons went on decreasing as they went down. At a certain depth, the particle detector did not detect any muon. At that depth of 2 km, all the muons are stopped by the overhanging rock. So the detector becomes capable of detecting the elusive neutrinos born from cosmic rays. Further experiments by
Sreekantan etal done in collaboration with physicists from Osaka University in Japan and Durham University, UK succeeded in detecting these neutrinos in 1965. The credit for this first detection of cosmic-ray produced neutrinos belongs to TIFR.

​

However the Kolar Gold Field mines were closed in 1995. Hence neutrino research in India stopped. The cosmic-ray neutrino research which was started in India, progressed further in Japan and brought success to the Japanese scientists. The Japanese scientists Koshiba and Kajita got the Nobel Prizes in 2002 and 2015 respectively.

​

Can we in India recover the lost opportunity? We can. That is the aim of the India-based Neutrino Observatory (INO) which is planned to be set up in Theni District, Tamil Nadu.

​

Bhabha and the Atomic Energy Training School

The scientists in the Indian Universities and research institutions must continue to work there and hence the scientists needed by the Department of Atomic Energy (DAE) must be created by the Department. With this view Bhabha created the Atomic Energy Training School in 1957. The scientists and engineers working in DAE and its various institutions were recruited only through this training school. One reason for the rapid growth of DAE and its institutions is the training school.

​

I was one of the trainees in the first batch. On the first day Bhabha gave the inaugural lecture. He described his vision for the future of India and the role of atomic energy and his plans and dreams. At the end of the lecture, one of us boldly asked: " What kind of position and job would you give us at the end of the training period?" All of us were a little shocked by this question. But Bhabha, without any hesitation, answered: "If you prove yourself, you will be given my position and job." This was no bluff. Anil Kakodkar who became the Chairman of AEC and Secretary of DAE in 2001 was a trainee from the sixth batch of the training school!

​

Bhabha and Atomic Energy

We already mentioned that as early as 1944 Bhabha pointed out that atomic energy must be used for peace. Bhabha was the President of the international conference "Atoms for Peace" organized by UNO in 1955.

​

Bhabha believed firmly that only atomic energy can provide the requisite energy for the all the people of the world. It is easy to prove that he is right, by a small calculation. Humans desire a comfortable life. All the countries want to reach the economical level attained by America and Europe. What is needed for all this is energy. If all countries use coal and petroleum, it is possible to prove by a simple calculation that all the coal and petroleum in the Earth will be exhausted in a few years. Further, our environment will be further spoilt by the use of coal and petroleum. The effect of atomic energy on the environment is much less. There are attempts to make use of solar power and wind power.  But these are not enough to satisfy our need.

​

Therefore, the only route to increase the standard of life of people is the atomic energy route pointed out by Bhabha. (There is another way, if people learn to live by reducing their needs. That is the way Mahatma Gandhi taught us.)

​

There are two methods to release nuclear energy. One is the fission of nuclei such as uranium and the other is the fusion of light nuclei such as hydrogen. In the International Atoms for Peace Conference in 1955, Bhabha emphasized the importance of this second way.

​

Since thorium is abundantly available in our country, Bhabha planned to use thorium in fission reactors. But much research is needed for the success of the thorium project. To get energy from the fusion process also much research is needed. Both types of research are being pursued. But success has not come so far and so Bhabha's dreams have not been realized.

​

Unfortunately, the DAE is involved in making nuclear bombs also. This must be stopped. India must use nuclear energy only for peaceful purposes.

​

Bhabha founded the Atomic Energy establishment at Trombay near Bombay. After his passing away, it was renamed as Bhabha Atomic Research Centre (BARC). Today this has become India's largest centre for science and technology. Two more centres for science and technology were established by DAE: one is the Indira Gandhi Centre for Atomic Research (IGCAR) at Kalpakkam near Chennai and the other is Raja Ramanna Centre for Advanced Technology at Indore. Institute of Plasma research at Gandhinagar near Ahmedabad is also part of DAE now.

​

            
 

Riding two horses

Bhabha's acumen for administration is clearly manifested in the two types of institutions that he created. TIFR was created for fundamental research. If the administration interferes with the work of the scientists, it will end up in disaster. Atomic energy centre has the aim of setting up reactors in the country. To create these institutions and set up rules and regulations for both, is like riding two horses. Bhabha succeeded in doing that.

​

The rules and regulations gave a lot of freedom to the scientists working at TIFR. The administration of TIFR was not given any power to control the freedom of scientists. Once, Bhabha himself called a meeting of all the administrators and said: " Your duty is only to see that research proceeds without obstacles and help the scientists in that. You must not try to rule or control the scientists." 

​

The scientists and engineers at atomic energy establishment did not enjoy such freedom. The work there was something that the Government wants done and to do that there were strict rules and regulations.

 

     
    
    
Bhabha's sight was always focussed on first rate, as far as ability and creativity was concerned. Bhabha's secret for his success was this: to invite those scientists who had proved themselves, to provide all the facilities for their research and to let them function independently. This is what contributed to the success of Govind Swarup of GMRT-fame and others. 
 
But today, all this has been forgotten. Administrators and politicians today interfere in our Universities and research institutions and use their power and authority. In this situation, how can Science progress?

​

Bhabha and Nehru

India's first Prime Minister Jawaharlal Nehru was an important reason for Bhabha's success in founding TIFR and Atomic Energy Establishment in such a short time. Nehru loved Science. To drive India in the path of progress by using Science, he worked actively and with passion. So Bhabha and Nehru became close friends. Each addressed the other as "brother". Nehru was very helpful and approved Bhabha's plans immediately. The friendship between Bhabha and Nehru was responsible for the rapid progress of India in the scientific field soon after it became independent in 1947.

​

End of an Era

on 14 January 1966, the plane that took Bhabha from Bombay to Geneva crashed in the Alps mountain in Switzerland killing everybody on board. Homi Bhabha died. India lost a great scientist and a great architect of India's Science and Technology. He was only 56! His achievements in a short span of life are breathtaking.

 

 
Reference:

Bhabha and his magnificent obsessions, by G Venkataraman, Universities Press.