Author: G.V. Pavan Kumar

Namaste, Hola & Welcome from G.V. Pavan Kumar. I am a Professor of Physics at the Indian Institute of Science Education and Research, Pune, India. My research interests are : (1) Optics & Soft Matter: Optically Induced Forces – Assembly, Dynamics & Function; (2) History and Philosophy of Science – Ideas in Physical Sciences. I am interested in the historical and philosophical evolution of ideas and tools in the physical sciences and technology. I research the intellectual history of past scientists, innovators, and people driven by curiosity, and I write about them from an Indian and Asian perspective. My motivation is to humanize science. In the same spirit, I write and host my podcast Pratidhvani – Humanizing Science.

Brillouin on Sommerfeld

“Everybody wondered (and still wonders) why the Stockholm committee systematically ignored Sommerfeld’s pioneer work in modern physics. Such an omission is actually impossible to understand.”

Leon Brillouin, in the foreword of his book WAVE PROPAGATION AND GROUP VELOCITY (1959)

Brillouin further mentions the teachers who taught him, and rates Sommerfeld among the best:

“I had the great privilege of attending, as a student, lectures given by some prominent physicists, such as H. A. Lorentz, H. Poincaré, and P. Langevin. But I was especially impressed by Sommerfeld’s mastery as a teacher.“

Conversation with Srubabati Goswami

Srubabati Goswami is a pioneering Indian physicist specializing in high-energy physics, particularly neutrino physics. She is probably the first Indian woman to earn a PhD in neutrino oscillations from the University of Calcutta. She advanced research at Physical Research Laboratory, Ahmedabad (PRL), Saha Institute of Nuclear Physics, and Harish-Chandra Research Institute before becoming Senior Professor at PRL. A fellow of India’s three science academies, she unravels neutrino mysteries and champions women in science.

In this episode, we explored her intellectual history and her remarkable journey as a physicist.

References:

  1. Srubabati Goswami | LinkedIn’. Accessed 16 January 2026. https://www.linkedin.com/in/srubabati-goswami-9b5ab520/?originalSubdomain=in.
  2. Dogra, Aashima. A Trailblazer Looks for the Keys to the Next Generation of Physics Research – The Wire Science. 7 September 2017. https://science.thewire.in/science/srubabati-goswami-neutrino-ino-dino-kamiokande-prl/.
  3. Godbole, Edited Rohini, and Ram Ramaswamy. LILAVATI’S DAUGHTERS. n.d.
  4. ‘Indian Academy of Sciences’. Accessed 16 January 2026. https://fellows.ias.ac.in/profile/v/FL2017008.
  5. Sciences (TWAS), The World Academy of. ‘Goswami, Srubabati | TWAS’. Accessed 16 January 2026. https://twas.org/directory/goswami-srubabati.
  6. ‘Srubabati Detangles Weird Phenomena’. The Life of Science, 6 September 2017. https://thelifeofscience.com/2017/09/06/srubabati-detangles-weird-phenomena/.
  7. ‘‪Srubabati Goswami – ‪Google Scholar’. Accessed 16 January 2026. https://scholar.google.co.in/citations?user=YbhShAcAAAAJ&hl=en.
  8. ‘The Neutrino Story: From Impossible Dreams to Unreachable Stars (ONLINE) by Srubabati Goswami – YouTube’. Accessed 16 January 2026. https://www.youtube.com/watch?v=XZKadiBqhrA.
  9. ‘Women Shaping Scientific Frontiers: From Lab Coats to Leadership (27 Stories of Women Leaders in Physics and Engineering) | Exotic India Art’. Accessed 16 January 2026. https://www.exoticindiaart.com/book/details/women-shaping-scientific-frontiers-from-lab-coats-to-leadership-27-stories-of-women-leaders-in-physics-and-engineering-hba517/.
  10. X (Formerly Twitter). ‘(1) Srubabati Goswami (@srubabati) / X’. 29 December 2025. https://x.com/srubabati.

Five Aspects of the Fifth Pillar – A Philosophical Perspective

In reference to a recent article on higher education in the Economic Times, a well-known tech entrepreneur and philanthropist wrote the following on X/Twitter: “75% of Indian higher education institutions still not industry-ready. Lot of work left to transform. But the 21st century requires education, research, innovation, and startups as four pillars of a university.”

This is a thought I do support, but I think there is one more important meta-pillar, perhaps a ‘foundation’ on which all these pillars are standing, and that is called ethics. Below are five aspects of ethics that I think need further attention.

  1. If one observes some of the major contemporary and pressing problems in our world, they can be connected to the ethical aspects of how humans function. A vital part of our educational system should re-emphasize this connection and make it central to everything that is done in a society.
  2. Ethics has two important elements to it: first, it has a philosophical grounding and connects to how humans function in a society. Second, it has an important connection to how trust in a society can be developed. Most of the discussions on ethics generally focus on the first element from a morality perspective, whereas the second point has an equally important utility and an economic connection.
  3. Ethical principles have great utility. It is important that we never keep it as an implicit aspect of human endeavour. Instead, we should start everything on the ethical grounds and build it up from there, including businesses, because a strong ethical foundation probably would be the best thing to happen for economic progress in any society, because trust is so important among human beings, and it is one thing that probably brings humans together. In the long run, the meaning of ‘prosper’ critically depends on the meaning of ethics. Being prosperous without being ethical is detrimental to any human pursuit. Zero-sum games are exciting, but in the limit of many games, the number of people who lose will be far more than the people who win. Instead, cooperative games have much larger dividends to all players and are inherently connected to a concept called as double thank you moment.
  4. The philosophy of ethics is something which the world has to revisit in greater detail, especially in an era where technological implications are driving human life in directions which we have not anticipated. One may think that raising ethical issues might hinder progress, but my argument here is that, instead of hindrance, one should look at it as an important requisite for human societies to not only survive but also to flourish. Large human endeavours cannot sustain without trust, and that trust is reinforced through ethical behaviour.
  5. Without ethical implications being factored in, it would be hard to really design anything related to technology. A case in point is the social media restrictions in countries such as Australia. Technology has the amazing capability to move fast before the philosophical debates can come in, but it does not mean that philosophy has to be completely ignored. The downstream of a scientific idea can become a product in a market, and positively impact society, but this evolution has a fellow-traveller, and that is ethics. The feedback loop is incomplete without the ethical considerations, and therefore, it should be looked at as an important ingredient in any human design.

There is an inherent connection between cooperation and trust, and that is founded on an ethical principle. The world requires an ethical recap, and it should be part of individuals, institutions, and governments. There is a rich history of ethics in all the cultures across the world, and it is worth revisiting them in a new light. Perhaps it is high time that we “Make Ethics Great Again.”

Saha and Bose translate Einstein

In physics, the general theory of relativity is one of the most remarkable achievements. It has turned out to be one of the most profound theories in the history of physics. In 1916, Albert Einstein proposed this theory, and it was confirmed in 1919.

Right after this confirmation, around 1920, two Indian gentlemen named Satyendranath Bose and Meghnad Saha translated Einstein’s German work into English. What you are seeing as an image is the remarkable book Principles of Relativity, containing the original papers by Einstein and Minkowski. This translation was done by M.N. Saha and S. N. Bose, who were then at the University College of Science, Calcutta University. It was published in 1920 by the University of Calcutta.

The book also contains a historical introduction by Mahalanobis, the celebrated statistician, although he was originally trained as a physicist himself. This historical introduction is itself quite remarkable.

If you look at the table of contents of this book, you will find the following:

  1. A historical introduction.
  2. The Electrodynamics of Moving Bodies, which is an important paper and is necessary for understanding what follows.
  3. A short biographical note on Albert Einstein was written by Saha.
  4. The Principle of Relativity, mainly the Minkowski papers, translated by Saha, along with an appendix.
  5. The General Principles of Relativity, Einstein’s epoch-making 1916 paper, translated by S. N. Bose, followed by notes by these gentlemen.

The historical introduction discusses the evolution of ideas that led to the fruition of the general theory of relativity. This turned out to be one of the most important expositions of the general theory of relativity, soon after the emergence of the theory and its subsequent confirmation by Eddington through his famous solar eclipse expedition. This is a remarkable document, and it is available on the Internet Archive.

ShuX in IISER Pune

Yesterday evening (10th Jan 2026), Shubhanshu Shukla, the recent Indian astronaut, was at IISER Pune as part of the ‘India Science Festival’. There was a huge crowd gathered to see and listen to him. Within IISER, it is rare to see such a massive gathering for a science event, and it was heartening to witness this on a Saturday evening. Thanks to schools and colleges in Pune, science and science-related activities get traction from the people of Pune (especially younger people). They enthusiastically participate in many events related to science.

 Such a gathering is very important for at least three reasons:

  1. It connects a scientifically oriented person to the public and thereby connects them to science.
  2. It showcases that there is some science-related activity happening within the Indian scene.
  3. It sends out a message to people that icons can be created out of people who do science funded by the public.

I would want to emphasize four other points:

  1. Scientific icons are as good as the science they represent. A major part of the credit should go to the organizations that supported and trained him, and this includes ISRO, NASA and the Indian Air Force.
  2. To put an astronaut in space, it takes a lot of effort at various levels of society. Public support is vital for such an effort. Public icons such as Shubhanshu Shukla are a good representation of what investment in science can do to the morale of the public, especially for young people.
  3. The created momentum should not be lost, given that recognizable people, such as astronaut Shubhanshu Shukla, have made an imprint on young people. This should be followed up with measures to recruit them for science and technology.
  4. Space science and technology, astronomy and astrophysics have always been among the most fascinating domains to attract people into science. Many Indian scientists and a past astronaut, Rakesh Sharma, have played an important role in this pursuit. One should not forget them.

Let me conclude with a word of appreciation for Pune city. It is not a capital city, but its enthusiasm for intellectual pursuits is high, and it attracts a lot of enterprising people (recently, there was a public policy conference that had some amazing people). If it can get a lift in its public infrastructure, it can create its own path in the landscape of science and technology.

Quantum Optics course – thoughts and notes

Jan 2026 – Apr 2026 – I am teaching a course on Quantum Optics. Below you will find some random thoughts and notes related to my reading. I will be updating the list as I go along the semester. You can add your comments below.

  1. Anyone interested in physics should know a bit about renormalized QED and the efforts that went behind it… It still remains a benchmark of how experiments and theory work in elevating each other…
    • Hari Dass (erstwhile, IMSc) on FB made an interesting observation:it’s unfortunate that after all those and subsequent developments, a mystery is being built out of renormalisation..it was the price to pay for assuming, without any justification, that the microscopic description held to arbitrarily small distances..wilson,schwinger and even feynman have clarified that the right way to do physics is to start with an effective description with a cutoff, which can be fully quantum in nature, and keep extending it to higher and higher scales with the help of further data, as well as with better theoretical understanding..
  2. “The photon is the only particle that was known as a field before it was detected as a particle.” 
    • This is how Weinberg introduces the birth of quantum field theory. He further adds:  “Thus it is natural that the formalism of quantum field theory should have been developed in the first instance in connection with radiation and only later applied to other particles and fields.”Ref: S. Weinberg (in Quantum Theory of Fields, p.15,  1995)
      • Sudipta Sarkar (IIT G) made an interesting observation in facebook:
        • “In some sense, it did right! Dirac started QFT with the effort to quantise radiation! But formally, it is not easy to write down the quantum version of electrodynamics owing to gauge symmetry. It took quite a bit of time to understand how to manage a quantum theory with massless states!“
        • My reply: “indeed..the reconciliation of symmetry was a bottleneck. I am also amazed by the progress of thought, especially by Dirac, who took the harmonic oscillator problem and treated it the way he did. Historically, the question of quantization of particles was already an established programme, but to quantize the field was indeed a major challenge, and hence ‘second quantization’.“
        • The concept of creation and annihilation operators is an intriguing one because it brings in the thoughts from the commutation relationship that existed in classical physics and transfers that into quantum mechanics. This intellectual connection is mainly attributed to Dirac, and historically, this has been one of the most important connections to be made. The question of field quantization already existed in 1920s, but it is thanks to Dirac who really made this connection in a systematic and mathematically consistent way.
  3. In the context of the quantum harmonic oscillator model of electromagnetic radiation, the shift from canonical variables such as position and momentum to creation and annihilation operators is a fascinating one. Interestingly, this progression further leads to the so-called number operator. It is also a progression from Hermitian to non-Hermitian and again back to a Hermitian operator. In the process of understanding the number operators, one realizes that the ground-state results in the so-called zero-point energy. Taken further, the commutation of the number operator with the electric field of the electromagnetic radiation results in the number-amplitude uncertainty. This further gives an insight into why the field amplitude has a non-zero spread, even for the n = 0 state, and therefore results in the so-called vacuum fluctuations.
    • It can’t get more quantum than this…
  4. An essay on Quantum States in Argand Diagrams: https://historyofscience.in/2026/02/03/quantum-states-in-argand-diagrams-vacuum-coherent-and-squeezed/