The Nobel Prize in Physics 2024 was awarded to John J. Hopfield and Geoffrey E. Hinton “for foundational discoveries and inventions that enable machine learning with artificial neural networks“. There has been much buzz surrounding this prize, especially in the context of whether these discoveries are indeed in the realm of mainstream physics. Many science commentators have questioned the choice and have provocatively dismissed it as ‘not part of mainstream physics’.
This has also brought into focus an important question: What is physics?
This question does not have a simple answer, given the rich history of the subject and its applicability over centuries. What we now call engineering is essentially an extrapolation of thinking in physics. New avenues have branched out from physics that cannot be readily identified as mainstream physics; a case in point is artificial intelligence and machine learning.
One of the aspects of mainstream physics is that the intellectual investment in the contemporary scenario is mainly driven by discoveries happening in the realm of quantum mechanics and general relativity. One of the mainstream problems in physics is to combine quantum mechanics and gravitation, which remains an unresolved task. Therefore, significant attention is paid to understanding these theories and verifying them through experimentation. Other areas and sub-disciplines in physics have become loosely connected to these two important theories.
There is another dimension to physics that is equally important and has vast applications: statistical physics. In statistical physics, the motivation comes from multi-particle systems and their applicability as models to understand our world, including biological systems. One utilizes knowledge from mathematics and statistics, combining them with physical laws to predict, invent and understand new forms and assemblies of matter. This thinking has been extrapolated to abstract assemblies and hence applied to a variety of situations. This approach has led to a revolution in how we can understand the realistic world because a statistical viewpoint is very useful for studying complex systems, such as many-body quantum mechanical aggregates (such as groups of electrons), dynamics of molecules inside a cell and the evolution of the stock market. Statistical physics plays a dominant role in all these situations. It has become a ubiquitous tool, making it difficult to directly connect it to basic principles of physics as taught in college textbooks and classrooms. It reminds me of a saying: if you are everywhere, then you are from nowhere.
This situation leads us back to the question: What is physics? John Hopfield himself offers an interesting definition related to this question, emphasizing that viewpoint is a crucial element. This perspective allows for greater freedom in using physics beyond conventional definitions. Among scientific disciplines, physics is always associated with its depth of understanding. This is a good opportunity to emphasize the breadth of physics, which is equally noteworthy.
In that light, the 2024 Nobel Prize in Physics should be welcomed as an expansion of the horizon of what constitutes physics. In a day and age where basic science has been questioned regarding its applicability to modern-day life and technology, this prize serves as a welcome change to showcase that basic science has played a fundamental role in establishing a contemporary tool of primary importance to society.
This point is particularly important because policymakers and politicians tend to focus on immediate issues and ask how they can influence them by using modern-day technology. Utility is central to this form of thinking. Given that basic sciences are often viewed as ‘not immediately useful’, this viewpoint diminishes the prominence of foundational disciplines: physics, chemistry, biology, and mathematics. In contrast, this prize reinforces the idea that building cutting-edge technology, which holds contemporary relevance and societal impact, has its roots in these foundational disciplines. In that sense, this prize is an important message because, like it or not, the Nobel Prize captures the attention not only of the scientific world but also of the public and, hence, of interest to politicians and policymakers.
Issac Asimov is attributed to have said: “There is a single light of science, and to brighten it anywhere is to brighten it everywhere.” The Nobel Prize in Physics 2024 fits that bill.
The title of this blog is the closing line of an autobiographical essay written by John Hopfield (pictured above), one of the physics Nobel laureates today: “for foundational discoveries and inventions that enable machine learning with artificial neural networks.”
In this essay, he retraces his trajectory across various sub-disciplines of physics and how he eventually used his knowledge of physics to work on a problem in neurobiology that further connects to machine learning.
The title of the essay is provocative(see below) but worth reading to understand how physics has evolved over the years and its profound impact on various disciplines.
Thanks to Gautam Menon for bringing the essay to my notice.
By the way, Hopfield and Deepak Dhar shared the 2022 Boltzmann medal, and after the award, he gave a wonderful online talk at IMSc, Chennai. Thanks to Arnab Pal of IMSc for bringing this to my notice on X.
Let me end this post quoting Hopfield from the mentioned essay:
What is physics? To me—growing up with a father and mother who were both physicists—physics was not subject matter. The atom, the troposphere, the nucleus, a piece of glass, the washing machine, my bicycle, the phonograph, a magnet—these were all incidentally the subject matter. The central idea was that the world is understandable, that you should be able to take anything apart, understand the relationships between its constituents, do experiments, and on that basis be able to develop a quantitative understanding of its behavior. Physics was a point of view that the world around us is, with effort, ingenuity, and adequate resources, understandable in a predictive and reasonably quantitative fashion. Being a physicist is a dedication to the quest for this kind of understanding.
When I was growing up, I always wondered about this. If the aim was to go to the top of the mountain, why not just take a helicopter and reach the summit? Then, I gradually realized that people climb mountains for a different reason: happiness through temporary pain. This transient, painful process of climbing motivates people to take up the challenge. If you look at the amount of time a climber spends on reaching the summit, it will be minuscule compared to the climbing time. The elaborate process and the preparation make climbing not only an adventure but also a meditation. There is joy in reaching the summit, but happiness comes from the climb, which starts as a painful step. Joy, in that way, is temporary. The climb, which is the process, is the happiness.
Then, can the climber focus on the climb and forget about the summit and destiny? Over the years, I have realized that any journey requires a point of reference, a temporary destiny. It tells the climber roughly which direction they must head towards to reach the summit – destiny. However, once this reference point is decided, it is better to forget about the summit and focus on the next step. Interestingly, each step becomes a mini-goal, keeping the motivation alive. The way to reach the summit is through multiple steps. Therefore, it is the repetition of steps that makes the journey. Even as they approach the summit, it is only through the individual step that they reach it. As they reach the summit, what has taken up the climber is still a tiny step. But this step was preceded by another step, and another preceded that. Then, they realize these steps are permanent, and the summit is a temporary stop. There is the realization that the summit is transient and the steps are permanent. Somehow, a tiny bit of discomfort with each step culminated in happiness. A transformation has happened.
As a professor and visiting faculty at various institutions, he has made significant contributions to the field. Sarukkai is the author of numerous books, including “Philosophy for Children,” “Translating the World,” “Philosophy of Symmetry,” and “What is Science?” He has also co-authored works exploring Indian philosophy, caste, and democracy. Sarukkai is the founder of Barefoot Philosophers, an initiative to bring philosophy to children and the public. With his diverse expertise and passion for accessible philosophy, Sarukkai is a captivating thinker in the intellectual landscape.
Listen, as we humanize science.
Note: The audio in the first 10 min is of lower quality
Here is what I have been learning from my observations :
1) Children tend to ask questions that are driven by curiosity. If these questions are refined, they turn out to be philosophical. Eg: Why do we live?
2) Adults tend to ask questions that are generally connected to economics. On average, their questions are more on ‘how’ than on ‘why’.
3) A dialogue is actually a volley of questions and answers. We somehow tend to under-appreciate this. What we generally ascribe to Socrates is something present in all cultures. It is worth exploring this questioning tradition in all cultures. Eg.: Tarka shastra.
4) A great way to engage with a book is to read it as a series of answers to implicit questions. I am amazed to see how interesting and active reading becomes. This also works for research papers and sometimes even on fiction.
5) A collection of questions is a sub-set of knowledge. The answers derived from these questions can lead to further questions. Following this process will give you a ‘body of knowledge’. There is some fractal nature to this.
6) Scientific thinking is essentially a systematic way of asking questions. The operational word here is ‘systematic’. The structure of these questions is such that it fosters further enquiry, but it is also open-ended. That way, it gives us room for creative thinking.
7) Creative thinking, in essence, is a question of effective combination. It becomes ‘creative’ when the sum of parts creates something new AND relevant. The conjunction is its vitality.
8) Finding an error in our thinking also originates in questioning. In fact, error analysis is a form of questioning from a different viewpoint. It requires us to shift our perspective, and the central question is where and when to shift?
9) Questioning is an inherent human quality. Fostering this is not only existential but also very useful. Etymologically “systematic treatment of an art, craft, or technique” means technology. If you observe, its roots are connected to scientific thinking (see 6).
10) Questioning is generally considered a part of the means to an end. If you observe, it is a means that never ends. Worth asking – Why?
To wonder is to be human. At the heart of wondering is questioning. As an individual and a collective, encouraging people to ask questions is one of the most important things we can do. Start with your children or young people around you. Encourage them to question you. Try to answer them honestly. If you do not know the answer, explore the answer with them. Emphasize that no answer is complete and is subject to revision upon new evidence and ideas. In my opinion, this process is the safest training you can give them as an adult and help them become informed citizens.
Along the way, teach them two things: 1) how to formulate a question and 2) pay attention to the tone of the question they ask.
Formulating a good question is a challenging task and requires iteration. Iterations mean patience. So, asking a good question is a training in patient thinking. Discourage rushing through. That does not mean the upper time bound is infinite. This means you shouldn’t settle for the default question. Question the question.
Next is the tone of the question. It is the tone which determines the intention of the question. If your intention is grounded in humility, curiosity and transparency, you will have a better chance of obtaining an answer. A question asked in a condescending tone generally discourages people from answering, even if their intention is not to conceal.
Of course, these are not general rules but guidelines that may be useful.
Conclusion: Pay attention not only to the substance of your question but also to the form of your question. A questioning mindset can be extrapolated to your everyday thinking. Gradually, it will become a way of life. Learning is more important than ego. When you realise this, questions become a great tool to explore the world.
In 1980s, every Friday morning, Akaashvani Bengaluru (a local radio channel of the state; language Kannada) woke me up with Bhimsen Joshi’s famous rendition – Bhaagyada laxmi baaramma. This song has stayed with me and somehow makes me nostalgic for the times we lived – a simple, lower-middle-class life. More than the devotional undertone of this song, what captured my attention was how it was beautifully adapted in a movie by Shankar Nag without compromising its authenticity. It showed me how art can be inclusive yet distinct.
I went to a local private English school. Those were the times when school education was affordable even for a lower-income family like ours, and now, if I look back, I did get a relatively decent primary education. Some of the teachers I remember had names: Firdoos, Christy and Geeta.
An interesting aspect of my upbringing was my exposure to various sports. It included cricket (of course), cycling, eye-spies, lagori, buguri,goli and bachha. The last three sports are unique. Buguri is playing with a top, where you spin the top with a tied rope. By releasing the rope skillfully, one can make the top rotate at a location of interest, be it on the floor or in the palm of your hand.
Goli is playing with marbles, where you compete with an opponent by hitting a marble with another. There were several games within the umbrella of this fascinating meta-game, and it was one of the most competitive sports I have played.
Bachha will be the most unfamiliar sport to many of you reading. It was typically played by children who grew up in lower-middle income surroundings, and the game was to use well-polished granite slabs that can fit your hand. This was made to sail over a tar road. The sailing of the stone had to be smooth, and the target of this throw was to dislodge a pile of old cigarette carrying paper boxes (without cigarettes) that had been collected over a long period of time. The whole point of the game was to hit the piled-up packs of these folded boxes and win them as a collection. Different boxes of cigarette brands had different values. Talk about capitalism !
Through the 1990s, the teenage years were memorable. Riding a two-wheeled motor vehicle made you feel you had evolved into an adult. It gave you the freedom to go to a petrol bunk and fill up the tank full of fuel (with tinge of kerosene) on a gear(care)less TVS 50. The picture that has stayed with me is the skilful handling of a bunch of currency notes by the guys who filled the petrol. They used to double up as cashiers (as they do even now), but then everything was to be dealt in cash, and the human processing speeds had to be good. Similar skills were evident with BTS bus conductors. A fascinating thing about them was that they had a whistle. This made their presence felt, and they were the representatives of the unique city culture of Bangalore. Their images are so iconic that many Kannada movies then had bus conductors as characters of their movies. Rajnikanth was one of the early ones to play this role. And yes, he started in Kannada movies, as did a few other Tamil superstars.
Deccan Herald was and is a newspaper that most of the Bengalurians are aware of. It had some wonderful commentaries on history and geography. Thanks to some of these articles by well-known writers, I was interested in these subjects. I was so motivated and encouraged by them that, as a school kid, I wrote them a letter. They published it. I remember it was a Saturday, and I spent my whole weekend staring at my article on paper. It was also a time when I learned about the great H. Narasimiaha distributing puffed rice to local people during a solar eclipse. His writings and thoughts sowed the seeds of rationality in me. Gradually, I transformed into an atheist, and over the years, I have adapted compassionate rationality as a way of living and thinking. This way has allowed me to appreciate my culture’s deep roots without compromising on rational thinking. It has given me a balance.
What was out of balance in my life was the pressure of education. The worst part of the late 90s was my pre-university education. Then, 11 and 12-grade education was part of pre-university college, and this exposed one to a life of partial independence. Unlike a bachelor’s degree, this time in college is boring, and everything is done to crack some silly exams that have ‘not so silly’ consequences on one’s career. With great fortune, I escaped a turbulent time and found myself doing BSc (Physics, Maths, Electronics), with a healthy amount of languages, including Sanskrit and English. Throughout this period, the wonderful libraries across the city were central to my education. There were many old public libraries in Bangalore, and one did not need any membership to read a book. I saw so many people preparing for civil service exams in such libraries.
In 2000s, I fell in love with physics. Astrophysics gripped my life and took me through an intellectual journey that has not stopped ever since. Intellectual pursuits are that way. One can vaguely remember their origins, but one will realize the effect on one’s life only after a while. Interestingly, it changes the character of a person. That is the power of education.
I went to Bangalore University to do my Masters in physics. This state-funded university’s semester fees were less than present-day woodland shoes. For the first time, I saw how education can be aspirational, inspirational, political, liberating, suffocating and fun. All at once. This was also the time I discovered that economics and politics have far-reaching consequences in scientific research.
This was also the era of my PhD at JNCASR. I started as a serious student of physics and ended my PhD as a serious student of science. This was transformative not only because I was exposed to new knowledge but also because I could contribute to knowledge. At the end of the first year of my PhD, I got an excellent opportunity to travel to the US. I attended a summer school at University of California, Santa Barbara.
Interestingly, this journey was the first time I took a flight on an aeroplane, and the trajectory was long and interesting as I flew around the globe (Bangalore to Bangkok to Osaka to Los Angeles) thanks to the limited funding. The biggest realization of my arrival in LA was a massive billboard of an iconic iPod silhouette advertisement. It is etched in my inner eye. My first travel within the US was a road trip from LA to Santa Barbara. What a ride!
After I finished my PhD, I moved to Barcelona and lived in Castelldefels. I shared my apartment with an Uruguayan (Spanish: uruguayos) couple and a cute dog. It was interesting that we were all immigrants. They spoke Spanish, but I did not, which impacted how we assimilated into the society. Although we did not speak similar languages, we could communicate very well with each other. That was an interesting lesson for me.
Then I moved to the US, and this was a time when Obama had just been elected into office. I have never seen a country undergoing economic recession and yet was so enthusiastic politically as the US. The ‘Yes We Can’ was an iconic campaign; I could see how it touched so many lives in the US. It was also a time when I was exposed to American professionalism and their excellent work culture. This has deeply impacted my thinking and how I look at work. It also made me realize the (positive and negative) powers of a free market economy. Again, it was an education.
In 2010, I got married, and started looking at life from a slightly long-term perspective. At the cusp of the decade, I moved back to India, and this time to Pune. Culturally, this is one of the wealthiest places in India. The flux of thought is high, and the people you get exposed to is often fascinating. It was also a time when I was building my lab, and I found how essential teamwork is. You always realize this when you are doing your PhD, but when you set up your group, you get a different grasp of how highly educated humans behave and coordinate for the greater good with a common goal.
Interestingly, these common goals can also align with personal career goals and growth. From a close quarter, I see how five years of focused work can transform people’s lives and thoughts. We need to pay more attention to the long-term work.
One of my life moments was to see my wife delivering my daughter. It made me feel human. I was there in that ward beside my wife, and those few minutes has transformed me forever. It also made me realize the power of human bonds. The day’s images are etched in my memory, and I thank biology for all that!
Now, we are in 2020s, and the pandemic has eaten away a few years. The early years also led to an explosion of information, and understanding the world is a continued challenge. An astonishing aspect has been that we, as humans, are still fighting wars. It indicates that we still do not understand each other, and cooperation is still a major goal to achieve. More work to do.
All through this journey, what has remained with me is reading, writing and talking to people. All people from all walks of life. Writing and talking has also encouraged me to use them as tools to look at the world. A lesson that I derive from all this: human cultures should use knowledge from the past and present and move towards the future. A forward-looking culture distills the best from every cultural exposure and adapts them to move forward. This is also a lesson from evolutionary biology, and perhaps a lesson for a beautiful country like India, that is Bharat, and many other magnificent things.
We are the people, and the wheel – the chakra, represents us on the move. This is the life I want to travel on : riding on a chakra of a forward-looking culture.
VISMAYA - History & Philosophy of Science 