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As an experimental physicist, Professor G. Ravindra Kumar works with lasers that are so powerful that they are able to recreate planetary conditions in the confines of the lab. With these lasers, Kumar and his team at the Ultrashort Pulse High Intensity Laser Laboratory (UPHILL) at the Tata Institute of Fundamental Research (TIFR) create extremely hot, ultra-dense plasma, picosecond bursts of magnetic fields a billion times stronger than the Earth’s and technology that could be used to build the next generation of particle accelerators.
In 2015, Kumar was awarded the Infosys Prize in Physical Science, earning him a spot on the Asian Scientist 100, an annual list of Asia’s most outstanding scientists. In this interview for Asia’s Scientific Trailblazers, Kumar shares with Asian Scientist Magazine what set him down the path of science in the first place, and how he hopes science education can change to the benefit of young Indian students.
Who or what influenced you to pursue a career in science? How did you end up in such an offbeat, unconventional and unusual career?
It all began with a friend in junior high school school, a couple of teachers and several sporadic events in my undergraduate life.
I was merrily coasting along the typical Indian school process assuming that if I did well in the school exams I was doing fine. One day, in junior high school the teacher was telling us about electricity and batteries. In the scenario that was typical in Indian schools at that time, no questions were asked of the teacher and everyone was just busy noting the key points of the lecture.
The next day, this friend asked me a question on that lecture and I tried to answer from what was taught in the class. He asked me more and more questions which all seemed so different from the questions that were in the text book. I realized that I had not learnt anything, which was quite a bit of a shock. He ended that discussion saying perhaps it was more important to understand the basics of the subject rather than just learn everything by rote and reproduce that in the examinations. I had a few more encounters like this and each one was more sobering and more revealing than the previous ones.
At first I was annoyed with him (also annoyed with myself that I had not realized this important point myself) but as I spoke more to him, I was convinced that real learning was not happening in the class. And given the system, the infrastructure in that government school in a small town and the typical style of teaching in Indian schools, there was no way it would happen. When I look back, I see what a crucial and important role this friend has played in my life. I lost touch with him soon after that year as I left to study in another town but I remember him even today. Perhaps he was my best teacher!
Later, in junior college (as the 11th and 12th grade are known in India), I had a physics teacher who would go beyond the textbook and tell us about stuff like relativity. We would wonder what he was talking about because the ideas all seemed strange but he made the point very effectively that there were exciting things beyond what we were learning (the books did not enthuse us at all). Yet another teacher encouraged us to read about things ourselves and present them to the class. There were not many volunteers, but fortunately I decided to be one and that helped a lot too.
When I look back, I feel fortunate to have had such encounters. At my undergraduate institution, there were bright students from all over the country (a big change from my small town in the southern part of India) and they had much better schooling than I did. And the orientation was totally towards thinking about concepts and solving problems and some great books were prescribed and made easily available for the courses. The course structure was well thought out and the learning broad-based in the first three years of the five-year programme. This, of course, had a major influence on the choices I made later.
What did you study?
Prof. Ravindra Kumar holds a B.E. (Hons) in Mechanical Engineering and M.Sc. (Hons) in Physics, both from the Birla Institute of Technology and Science, Pilani, in Rajasthan, India. He obtained his Ph.D. from the Department of Physics in IIT-Kanpur in 1990. After a year of postdoctoral work, in 1992, he joined the Tata Institute of Fundamental Research, Mumbai, in the group now known as UPHILL (Ultra-short Laser Pulse High Intensity Laser Laboratory) in the Department of Atomic and Molecular Physics. At TIFR, he has established a strong laboratory for studying the physics of hot dense matter produced by ultra-short laser pulses.
What is ultrahigh intensity physics and what is it used for?
Ultrahigh intensity physics is physics done with high power, short laser pulses. The pulses can be as short as a few tens of femtoseconds (one femtosecond is a thousandth of a millionth of a millionth of a second) and they are focused on micron-scale targets.
The focal spot has a very high light intensity and the electric field there can far exceed the binding electric field between a nucleus and electron inside an atom. This extreme intensity can therefore rapidly strip off many electrons from atoms in the focal volume and leave a hot, ionized gas on the target called plasma.
This plasma has conditions similar to those in astrophysical objects. Thus we are able to mimic on a lab-scale, extreme conditions prevalent in most of the universe. This plasma is also very exciting for applications as it is a source of electrons and ions accelerated to high energies and the resulting x-ray and neutron emissions. It thus serves as a table-top source of a variety of particles that are emitted in a matter of femtoseconds or less.
Applications have already been demonstrated or are being explored in imaging, material modification and therapies. The use of such lasers will significantly reduce the size of the next generation of particle accelerators.
Tell us more about some of the most exciting projects happening at UPHILL.
Firstly, the word uphill is usually used to imply that something is going to be difficult and perhaps not desirable as in ‘an uphill task’. When we were looking for a name for our lab, this acronym came up automatically; ultrashort pulse high intensity laser laboratory is UPHILL! After we christened ourselves thus, we realized there was another message in this—that we have higher intensities to climb to and many more peaks to conquer!
At UPHILL, we are and will continue to be excited by the basic science of high energy density plasmas. At the moment, we are (a) exploring ways to ‘see’ the fast electrons created in the plasma as they travel through the solid medium behind, (b) simulating on a lab table astrophysical conditions like turbulence in the solar wind, (c) devising novel radiation sources based on nano-structuring of the target surface and (d) controlling the laser absorption of these plasmas. We pursue any basic science question that comes up in the broad area.
What are you personally working on at the moment?
My students and I are doing several experiments on establishing the astrophysical analogs in laser produced plasma like shock driven terahertz (trillion Hz) material oscillations and giant magnetic field turbulence. Key results on the latter aspect were published in the Proceedings of the National Academy of Science in 2012 and one more paper has recently been published in Nature Communications.
We are also addressing fundamental questions on the transport of giant current pulses of relativistic (close to the speed of light) electrons in solids. The physics is extremely challenging because of the complications caused by plasma instabilities. We need to get more data out and the research also demands high-level computer simulations.
What would you say has been the secret to Tata Institute of Fundamental Research (TIFR)’s success?
TIFR is a unique institution which brings in close contact bright, highly motivated researchers across many scientific disciplines. The interactions among colleagues are extremely enriching and may times lead to unexpected lateral advances. TIFR has been generously funded so far (and we hope this will continue!) and the level of ambition and accomplishment is challenging and inspiring at the same time.
We are expected to do important things and do them well. It is an institution where blue sky research is the main goal, unencumbered by the pressure of finding applications for every scientific advance one makes.
What is one thing you would change about the way science is done in India if you had the chance?
I would like to see major changes in science education at all levels. There continues to be a lot of rote learning, which does not nurture creativity. The learning should become more exploratory, should involve more problem-solving and innovative. Critical as well as lateral thinking should be nurtured from the school level. Whatever it takes must be done—well-paid teachers, good infrastructure and labs. Teaching and learning science should be seen to be a joyful activity!
At the level of research, I would like to see orders of magnitude more governmental funding for basic research. Indian governments have been supportive of basic science no doubt, but the size of the active, well-funded scientific community is still very small.
We need many more Indian scientists funded at the level of those in advanced nations and competing with them on top research problems. We need to increase our high-quality scientific mass much more. Breakthroughs and discoveries can then be expected to arise more often. India needs to be a much bigger player on the global scientific scene, answering all questions big and small. In fact, it should become a country where people of all nationalities should be eager to come and pursue science.
India has made tremendous advances with its space program in recent years. What other developments would you like to see in the next decade?
Yes, the space program has done very well and has showcased our technological competence. India has also done well in atomic energy programs. Though these appear to be purely applied areas, they rest on basic science that has been done over many years. I would like to see much more top quality basic science being done in India. The applications, technologies etc. will follow automatically.
India has many challenges in energy, healthcare and environment preservation and the people at large seem to be concerned about all these issues. There is much more awareness than say twenty, thirty years ago. I believe that safe and sustainable energy may be an important issue in the next decade, as India tries to go faster. The solutions to all these problems will lie in the basic science that will be done in this country.
What keeps you motivated?
The fact that there is so much to be done and learnt and the humbling realization that I know so little! Everyday I read or learn something so interesting that it makes me want to know more. Over the years, I have developed interest in broad areas of science and that keeps me want to see how cross connections can be made.
Finally, what advice do you have for young scientists in Asia?
Science is a global activity and getting an opportunity in science is a privilege. Pursue the goals you are passionate about and stay motivated to meet challenges that are typical of developing countries. Collaborate extensively across the world, learn from whoever you can but strike firm roots in your own country and see that science flourishes there. And actively mentor younger scientists and students!