My guest this time is Professor Robert T. Pennock, University Distinguished Professor at Michigan State University, with appointments in Lyman Briggs College, the Department of Philosophy, and the Department of Computer Science and Engineering: https://pennock5.msu.domains/
Robert’s research explores the deep connections between science, ethics, and philosophy. His recent book, An Instinct for Truth, presents science as a moral discipline grounded in intellectual virtues like honesty, curiosity, and humility.
At the BEACON Center for the Study of Evolution in Action, he leads interdisciplinary work on digital evolution, using artificial life systems to explore questions about complexity, adaptation, and the evolution of intelligent behavior.
In this episode, we explore his intellectual journey with an emphasis on philosophy of science.
Miller, Jon D, Belén Laspra, Carmelo Polino, Glenn Branch, Mark S Ackerman, and Robert T Pennock. 2024. “Citizen Attitudes toward Science and Technology, 1957–2020: Measurement, Stability, and the Trump Challenge.” Science and Public Policy 51 (3): 526–42. https://doi.org/10.1093/scipol/scad086.
Below is a small experiment with ChatGPT (GPT-4o, which is OpenAI’s most advanced model as of July 2025).
I asked for thoughts (from authentic sources) from Indian writers on the nature of the writing process (handwriting vs typewriting).
It confidently gave me quotations from Rabindranath Tagore, R.K. Narayan and U.R. Ananthmurthy. I was intrigued, and below is my conversation:
me: list the quotes from Indian writers above and give the exact sources
Chatgpt: I couldn’t find reputable sources for the exact quotes I previously suggested by Indian writers—so it’s safer to reconsider them.
This is something I have been observing with LLM chatboxes, especially when it comes to the sources that may not be mainstream. One may even say it is hallucinating, but after enquiring further, it said:
The quotes I initially provided appear to be popular paraphrases or second-hand interpretations, but none could be verified in primary texts or reliable interviews.
Then, it asked me if I wanted to use authentic sources to be presented to corroborate the initially mentioned sources. I said yes, and below was its reply:
Here are verified quotes from Rabindranath Tagore, with clear attributions to reliable sources—unfortunately, I couldn’t locate authenticated quotes for other Indian writers on writing methods
The quotes that it gave were peripheral to my initial question. It identified two to three quotations, but none of them were directly connected to my initial query.
There may be at least 2 hypotheses that I can draw from this, which need further testing:
ChatGPT and its kind may be getting trained more intensely on sources that are mainly anglophonic, and its geographical distribution of sources may be skewed. Online literary sources from countries such as India may not be as dense as, say USA, the UK or even some European countries. Will depositing more authentic sources online, including their translations, help the authentic discovery of information from countries such as India?
With the current developments and model training, there may already be a bias in the answers that LLM chatbots give. It may reinforce many viewpoints from Western repositories that may sometimes be disconnected or irrelevant to the user outside Western geographies. In that sense, new information is being built on old information. Are we entering a stage where data deposition asymmetry is creating an asymmetry of discovery?
I know these questions are not trivial to answer, but for LLM chatboxes to be authentic, they need to address questions with proper citations. I know some of them are trying to do that (eg, perplexity AI), but I find the links it provides for certain focused questions are not up to the mark.
My inference:
I am cautiously optimistic about the developments and achievements in source-based LLM interfaces, especially when you feed an authentic source (eg, NotebookLM).
But LLM chatboxes may be hyped when:
It comes to its capability of sourcing authentic information, and
The immediacy of replacements of existing knowledge systems.
LLM chatboxes should be treated as an experimental tool for utilitarian tasks where the information can be verified independently.
It is important to take the bottom line of ChatGPT seriously: ‘ChatGPT can make mistakes. Check important info.‘
In this episode, we discuss Shubashree’s journey from earning a PhD in physics to building a career in science journalism. She talks about her experiences writing for The Hindu and her current role as Associate Editor at IIT Madras’ Shaastra magazine. As a national award-winning journalist, Shubashree shares insights into making scientific ideas accessible to a wider audience, the challenges she has faced in the field, and her advice for aspiring science writers. This conversation explores her career transition, the role of science communication, and the importance of clarity in sharing scientific knowledge.
In 1972, P. W. Anderson wrote what is considered one of the most remarkable essays in the history of physics, and the title of that essay is “More is Different.” In the essay, Anderson was trying to make a case for emergence, where new, interesting physical properties can emerge by the combination of matter, which you would not anticipate if you had just kept it as an individual entity.
One of the aspects related to this essay is also the thought that reductionism has its limitations and that groups act very differently compared to individuals. The higher-level rules that can emerge from the combination of small entities are actually very different from the rules that are applicable to individual entities.
For example, if you consider electrons in a solid, you have the emergence of properties of electrons such as magnetism or superconductivity, or, for that matter, putting molecules inside a compartment and, lo and behold, life arises out of that. This has turned out to be one of the most influential ways of thinking in physics because it opened up a new avenue for understanding complex systems not as just combinations of simple systems but as the emergence of properties.
Very interestingly, this essay does not actually mention the word “emergence” at all, but the concept is so fascinating that it has turned out to be one of the most influential essays ever written in physics. The whole point about this particular essay is that the whole is more than the sum of its parts, and P. W. Anderson has to be remembered for this magnificent essay.
Cover of ‘Absorption and Scattering of Light by Small Particles’ by Craig F. Bohren and Donald R. Huffman.
It is important to read good books. Astrophysics, quantum mechanics, and gravity (including attempts to combine them with quantum mechanics) have been at the forefront in terms of popular physics imagination. These are wonderful subtopics of physics, but there are a few others that need equal emphasis. So, here is my attempt to fill this gap with some book recommendations.
The first one in the optics community is just called ‘Bohren and Huffman’ and is one of the best technical books I have read and continue to read. It is humorous and filled with wonderful insights that still engage researchers and students alike.
Craig Bohren, a theoretical physicist, is a wonderful writer, and you will see more of his books discussed here.
The book introduces the scattering matrix from a ‘light scattering’ viewpoint, and has a direct connection to laboratory measurements.
Humour is one of the key aspects of this book (as with others from Bohren), and the title of chapter 8 gives a nice glimpse: “A Potpourri of Particles”
There is a famous section in Chapter 11 with the heading – “Extinction = Absorption + Scattering” that wonderfully explains the physics behind it.
Overall, an outstanding book for understanding optics from an electromagnetics viewpoint and also to learn how electromagnetism is harnessed to understand interactions at the classical spatio-temporal scales.
Read this if you are interested in physics…It is a delight!
Today, I complete 15 years as a faculty member at IISER-Pune. I have attempted to put together a list of some lessons (based on my previous writings) that I have learnt so far. A disclaimer to note is that this list is by no means a comprehensive one, but a text of self-reflection from my viewpoint on Indian academia. Of course, I write this in my personal capacity. So here it is..
People First, Infrastructure Next As an experimental physicist, people and infrastructure in the workplace are of paramount importance. When I am forced to prioritize between them, I have chosen people over infrastructure. I am extremely fortunate to have worked with, and continue to work with, excellent students, faculty colleagues, and administrative staff members. A good workplace is mainly defined by the people who occupy it. I do not neglect the role of infrastructure in academia, especially in a country like India, but people have a greater impact on academic life.
Create Internal Standards In academia, there will always be evaluations and judgments on research, teaching, and beyond. Every academic ecosystem has its own standards, but they are generalized and not tailored to individuals. It was important for me to define what good work meant for myself. As long as internal standards are high and consistently met, external evaluation becomes secondary. This mindset frees the mind and allows for growth, without unnecessary comparisons.
Compare with Yourself, Not Others The biggest stress in academic life often arises from comparison with peers. I’ve found peace and motivation in comparing my past with my present. Set internal benchmarks. Be skeptical of external metrics. Strive for a positive difference over time.
Constancy and Moderation Intellectual work thrives not on intensity alone, but on constancy. Most research outcomes evolve over months and years. Constant effort with moderation keeps motivation high and the work enjoyable. Binge-working is tempting, but rarely effective for sustained intellectual output.
Long-Term Work We often overestimate what we can do in a day or a week, and underestimate what we can do in a year. Sustained thought and work over time can build intellectual and technical monuments. Constancy is underrated.
Self-Mentoring Much of the academic advice available is tailored for Western systems. Some of it is transferable to Indian contexts, but much of it is not. In such situations, I find it useful to mentor myself by learning from the lives and work of people who have done extraordinary science in India. I have been deeply inspired by many people, including M. Visvesvaraya, Ashoke Sen, R. Srinivasan, and Gagandeep Kang.
Write Regularly—Writing Is Thinking Writing is a tool to think. Not just formal academic writing, but any articulation of thought, journals, blogs, drafts, clarifies and sharpens the mind. Many of my ideas have taken shape only after I started writing about them. Writing is part of the research process, not just a means of communicating its outcomes.
Publication is an outcome, not a goal Publication is just one outcome of doing research. The act of doing the work itself is very important. It’s where the real intellectual engagement happens. Focus on the process, not just the destination.
Importance of History and Philosophy of Physics Ever since my undergraduate days, I have been interested in the history and philosophy of science, especially physics. Although I never took a formal course, over time I have developed a deep appreciation for how historical and philosophical perspectives shape scientific understanding. They have helped me answer the fundamental question, “Why do I do what I do?” Reflecting on the evolution of ideas in physics—how they emerged, changed, and endured—has profoundly influenced both my teaching and research.
Value of Curiosity-Driven Side Projects Some of the most fulfilling work I’ve done has emerged from side projects, not directly tied to funding deadlines or publication pressure, but driven by sheer curiosity. These projects, often small and exploratory, have helped me learn new tools, ask new questions, and sometimes even open up new directions in research. Curiosity, when protected from utilitarian pressures, can be deeply transformative.
Professor as a Post-doc A strategy I found useful is to treat myself as a post-doc in my own lab. In India, retaining long-term post-docs is difficult. Hence, many hands-on skills and subtle knowledge are hard to transfer. During the lockdown, I was the only person in the lab for six months, doing experiments, rebuilding setups, and regaining technical depth. That experience was invaluable.
Teaching as a Social Responsibility Scientific social responsibility is a buzzword, but for me, it finds its most meaningful expression in teaching. The impact of good teaching is often immeasurable and long-term. Watching students grow is among the most rewarding experiences in academia. Local, visible change matters.
Teaching Informally Matters Teaching need not always be formal. Informal teaching, through conversations, mentoring, and public outreach, can be more effective and memorable. It is free of rigid expectations and evaluations. If possible, teach. And teach with joy. As Feynman showed us, it is a great way to learn.
Foster Open Criticism In my group, anyone is free to critique my ideas, with reason. This open culture has been liberating and has helped me learn. It builds mutual respect and a more democratic intellectual space.
Share Your Knowledge If possible, teach. Sharing knowledge is a fundamental part of academic life and enriches both the teacher and the learner. The joy of passing on what you know is priceless.
Social Media: Effective If Used Properly Social media, if used responsibly, is a powerful tool, especially in India. It can bridge linguistic and geographical divides, connect scientists across the world, and communicate science to diverse audiences. For Indian scientists, it is a vital instrument of outreach and dialogue. My motivation to start the podcast was in this dialogue and self-reflection.
Emphasis on Mental and Physical Health In my group, our foundational principle is clear: good health first, good work next. Mental and physical well-being are not optional; they are necessary conditions for a sustainable, meaningful academic life. There is no glory in research achieved at the cost of one’s health.
Science, Sports, and Arts: A Trinity I enjoy outdoor sports like running, swimming, and cricket. Equally, I love music, poetry, and art from all cultures. This trinity of pursuits—science, sports, and the arts—makes us better human beings and enriches our intellectual and emotional lives. They complement and nourish each other.
Build Compassion into Science None of this matters if the journey doesn’t make you a better human being. Be kind to students, collaborators, peers, and especially yourself. Scientific research, when done well, elevates both the individual and the collective. It has motivated me to humanize science.
Academia Can Feed the Stomach, Brain, and Heart Academia, in its best form, can feed your stomach, brain and heart. Nurturing and enabling all three is the overarching goal of academics. And perhaps the goal of humanity.
My academic journey so far has given me plenty of reasons to love physics, India and humanity. Hopefully, it has made me a better human being.
Duff’s famous physics textbook from 1900 (5th edition) owned by YukawaYukawa’s name on the bookHideki Yukawa’s picture on the Nobel website
Apart from sipping the wonderful Japanese coffee and exploring the streets of Kyoto on foot, I have been looking into the archives of Kyoto University. I am mainly searching for records and books related to their physics department, and obviously, one of the names that pops out very often is Hideki Yukawa.
Yukawa was one of the Nobel laureates from this university. He obtained his Nobel Prize in Physics in 1949 for his prediction of the existence of mesons on the basis of theoretical work on nuclear forces. He is a big name in physics, and there is a physical potential named after him, which means one can understand the intellectual heft he carries as a physicist. Yukawa spent most of his scientific career at Kyoto, specifically at the Kyoto Imperial University (now, no more imperial :-) ), and is regarded as one of the inspirations for a battery of many excellent theoretical physicists to have emerged out of not only Kyoto but also Japan, and perhaps many parts of the world. While looking through the archival records, I came across one of the textbooks owned by Yukawa, which has his signature on it. It made my day !
The textbook titled “A Text-Book of Physics,” edited by A. Wilmer Duff, is a classic. Yukawa had the 5th edition (1921), and this book went on to have 3 more editions. I hope to write more about this particular textbook because the author, Wilmer Duff, had a connection to Madras University (as a Professor) in India and was also on the faculty of my post-doc alma mater – Purdue University !
The scientific world is a small place with unanticipated, wonderful connections :-)
K. Sridhar is a theoretical physicist and author currently at Azim Premji University, Bengaluru. Formerly at TIFR Mumbai, his research spans high-energy physics, including extra dimensions and supersymmetry. Sridhar also engages deeply with philosophy, literature, and education. He is the author of Particle Physics of Brane Worlds and Extra Dimensions (Cambridge University Press) and co-editor of Breaking the Silo: Integrated Science Education in India. In this conversation, we discuss his intellectual pursuits, including his recent novel Ajita.
Welcome to essays in the global history of physics, where we discuss people, ideas and technology connected to physics in the historical context. Let me explain why the global history of physics is important. Physics, as you know, is one of the central disciplines of natural sciences from which various branches of science and technology have emanated.
Understanding the evolution of such an important output of human thought is imperative. It not only gives us a glimpse of how people over the ages have thought about ideas but also reveals how those ideas are connected to philosophical and technological questions that were of interest to people in the past. In fact, it is that dual connection of physics to philosophy and technology that makes it interesting, important and intellectually rich.
This series of essays aims to capture the historical evolution of physics by paying attention to the global evolution of the subject. In doing so, we will visit the people from the past and learn about their ideas and technologies that eventually led to the topics within physics.
Here, I need to emphasize the global aspect of history. Conventionally, the history of science as a discipline has been criticized for being Eurocentric in nature. In recent years, as highlighted by James Poskett’s excellent book Horizons (1), there has been an emerging scholarship in the history of science to reveal a decentralized evolution of science and that includes some developments in physics itself. In these essays, I will give credit to people, ideas and technology irrespective of their origin and emphasize curiosity as a basic human instinct prevalent across space and time.
This thought reinforces science, specifically physics, as a global intellectual pursuit over many ages and times. The way I will do this is to take on a particular branch of physics and discuss its evolution in chronological order. Of course, my aim is not to cover everything that is known but to highlight some interesting developments in that field with attention to some interesting people, ideas, tools and technologies at the relevant place and time.
Such an exercise cannot be done in one single essay. So, I intend to cover the chronological evolution with a series of essays spanning all the branches of physics. Yes, it will be a long journey, and I hope you will accompany me in this one endeavor.
2. How a physical phenomenon is explained.
One starts with a concrete situation of a particular problem. Associated with this situation is a general law. One applies the general law to the situation in a logical manner and utilizes mathematical descriptions where precision is needed. This logical and mathematical description leads to an explanation witha concrete prediction. Observations must test this prediction. The ability to predict a future observation is one of the remarkable traits of science in general and physics in particular (2). It is through this ability to predict that one can envisage the utility of a physical concept. That utility forms the seed of development towards technology.
As you may observe, there is a nice connection between scientific inquiry and the eventual realization of technology. This connection is what makes science and technology go hand in hand. Importantly, this is one of the outstanding features of physics and historical explanation, as we intend to do in these essays, which will justify the claim.
This connection between science and technology is not a one-way coupling. In fact, many interesting questions in physics have emerged out of technological development across various eras of human history. This recognition of jugalbandhi between science and technology is at the heart of the essay series.
Physics has played a critical role in engineering civilization over the centuries. This role has been explicit in recent times, say around the last 300 years or so. But what is interesting is that inquiries in physical sciences have implicitly influenced the growth of a civilization.
This growth is not only materialistic but also intellectual in nature. Therefore, understanding the evolution of physics gives us a glimpse of the evolution of humankind. Of course, it may not be the complete picture, but at least we learn about people, ideas and technology that gave rise to the world that we identify as a physical, real entity.
3. Engineering Civilizations
Let us start with some ancient civilizations. The oldest tools used by humans were stones. In fact, the ‘Stone Age’ gets its name from this. According to archeological explorations, the earliest stone tools found in Lomekwi, Kenya, date back to 3.3 million years ago (3). This is the Paleolithic age, in which hunting and gathering were the main occupations of human beings. The stone tools found within India at Attirampakkam, a village close to Chennai in Tamil Nadu, date back to around 300 thousand years ago (4). From such archeological evidence, humans were acquainted with toolmaking long ago. Towards the Neolithic age, we also have evidence of pottery in civilizations, indicating a gradual change to farming and agricultural occupations that were assisted by toolmaking based on clay and fire. I need to emphasize that knowledge of these tools was handed over from one generation to another without a formal writing process. The oldest written record dates to around 3500 BCE in the form of a cuneiform script from Mesopotamian civilization, which is somewhere around present-day Iraq (2). Such writing itself needs small tools, such as a stylus and a platform, such as clay, to imprint the written text. Well before any form of writing became part of any civilization, tools and structures had to be invented.
An interesting element of the Indus Valley Civilization was that they used measurement scales (5). In the Harappan museum, one can find a linear scale made of a shell that has nine divisions with a small circle engraved on it. A periodically divided scale indicates a quantitative measure of length and indicates the sophistication of thought, both from device and utility viewpoints.
A remarkable aspect of this scale is the utility of the shell as the material. Given that shells are robust and can sustain large temperature fluctuations, they make for an excellent choice as a material for scale. One must really marvel at how humans came to the point where such a design was implemented without modern tools, scientific knowledge or a written script.
To emphasize this fact, one of the earliest texts from the Indus Valley civilization dates to around 3000 BCE. Of course, in this case, the script is yet to be deciphered completely. What is interesting is that ancient civilizations achieved remarkable engineering feats even before any formalization of scientific disciplines, including physics, came into the picture.
This is because for civilization to survive, grow and sustain, they had to manage their natural resources and construct structures. These tasks would not have been feasible without an intricate understanding of how things work and how they can be used to construct physical structures. This can be achieved only through certain tools and techniques.
The civilizations would not have evolved without this engineering and, therefore, deserve credit as a human achievement. These tools and techniques have implicit physics in them. Of course, there was no formal discipline called physics until around 300 BCE, but the empirical knowledge about tools and techniques for construction was already present long before physics became a formal discipline of science.
4. The role of philosophy
As human beings cultivated crops, their mobility was confined to a smaller region compared to the hunter-gatherer era. This settlement at a place gave humans leisure to think and wonder about nature. As a consequence of this thinking, philosophical thoughts emerged (6).
Questions pertaining to philosophy, such as what life is and how humans live and interact with nature, occupied human minds. This exploratory era also gave rise to the need to understand the world, explore nature and harness it. Inquiries pertaining to the motion of celestial objects and that of common living and non-living things captured the attention.
To understand the intellectual foundations of physics, one needs to understand its connection to philosophy in general and philosophy of science in particular. The connection between reality and physical law is through an abstract formulation (2). Reality has its own complications, and a physical law retains only a small set of the complications that are evident in reality.
Although this connection between reality and a physical law looks to be straightforward, historically, there has been a large intellectual struggle to come to this point. It has not been an obvious task to connect reality to physical laws. And by studying the history of physics, it is evident that the route has been anything but smooth.
Another important aspect I need to emphasize is how reality becomes a raw material for scientific investigation. In essence, reality provides a kind of formless raw material on which physical laws can be formulated. These physical laws are drawn from a simplified structure of reality, and there is a process of encoding reality in a language that is amenable to scientific investigation.
This process of going from a multi-faceted reality to a slightly more precise physical law is done through assumptions, and these assumptions play a critical role. The pathway from reality to general laws has been through inductive methods, at least in the historical context. In the inductive method, there is an extrapolation from the finite to the general principles.
Based on certain observations in a concrete situation, one derives a general law. Now, the question is, how does one derive such a general law? This generalization is based on a logical process, and one of the best tools to implement logical analysis is mathematics. This is where the role of mathematics becomes so important in physics. If one needs to go from a concrete, realistic situation to an abstract principle, one will have to utilize mathematical tools such as geometry to convert the reality into an abstract formulation. An important aspect of physics and science, in general, is that once this abstract formulation has been postulated, the physical law can be tested going forward. The results can be checked by performing observations, and these observations can confirm or reject the induced hypothesis.
When it comes to the observation, there are two elements. The first is the observed object, and the second is the observer themselves. The demarcation between the observer and the observed object seems trivial; historically, it has not been the case. Because the observed object can interact with the observer, the physical laws that are derived from such observations must ensure that the observers themselves are not perturbing the physical reality.
Also, the judgment of objectivity itself is a complex process because the criteria of truth have a social connection. This means what we call a factor of truth is closely connected to the social realities in which the observation is performed. This social connection brings in another layer of complication, and one must understand the philosophy behind these processes.
As you can see, formulating science and, in our case, physics has not been a trivial task, given that these philosophical questions must be addressed to get a satisfactory answer. Understanding and discriminating science from other forms of human activity has not been a trivial exercise either, but it is with the help of philosophy that progress has been made.
This also highlights the intricate connection between philosophy, physics, experimental observation and technological developments as a network of events that interact with each other. Each part of this network plays a critical role and, many times, feeds back important information in the process. Therefore, to understand physics, we need to not only appreciate the philosophical questions but also be aware of technological developments.
Because many of the developments in the realm of scientific philosophy were motivated by technology and vice versa, this is also the reason why the history of physics is so interesting. It brings together all these epistemological components into one single platform and creates an intellectual magic that has played a critical role in understanding nature and the universe, that which can be observed and, in some cases, that which cannot be observed.
So, how did ancient people think about a subject called physics? What were the initiating thoughts of philosophers that led to physics? If we want to address these questions, we need to pay attention to some of the philosophers who thought and wrote about science. Among them, one of the earliest to do so was Aristotle. In the next essay, we will discuss his physics.
References:
[1] J. Poskett, Horizons: A Global History of Science. Penguin UK, 2022.
[2] K. Simonyi, A Cultural History of Physics, 1st edition. Boca Raton, Fla: A K Peters/CRC Press, 2012.
[4] S. Pappu, Y. Gunnell, M. Taieb, J. Brugal, and Y. Touchard, “Excavations at the Palaeolithic Site of Attirampakkam, South India: Preliminary Findings,” Curr. Anthropol., vol. 44, no. 4, pp. 591–598, 2003, doi: 10.1086/377652.
[5] S. Guha, A History of India through 75 Objects. Hachette UK, 2022.
[6] P. Adamson, Classical Philosophy: A history of philosophy without any gaps, Volume 1. in A History of Philosophy. Oxford, New York: Oxford University Press, 2014.
