Toys, Geim and Gupta

Recently I came across an editorial in Nature Physics, titled as Physics is our playground, which emphasized how playfulness has had an important role in some of the major inventions and discoveries in physics.

A particular example of this is the discovery of graphene, and how it has evolved into one of the most important topics in condensed matter science. Nowadays graphene is used as ‘Lego’ blocks to build higher order structures and the so-called ‘Van der Walls’ heterostructures are one of the most exciting applications of 2D materials. What started as a playful project in the lab has now turned out to be an important part of emerging technologies.

Two important inferences can be drawn from the playful attitude towards doing science :

First is that making modular elements and stacking them creatively can lead to emergence of new structures and function. Anyone who has used lego blocks can immediately relate to it.

Second is that toys are powerful research and teaching aids. Please note, that I emphasized research and teaching here. This is because toy-models are ubiquitous in research, and they help us create modular state of a problem in which unnecessary details are discarded and only the essential parts are retained. This way of thinking has been extremely powerful in science and technology (for example : see ball and stick models in chemistry and mega-construction models in civil engineering )

When it comes to toys and education, there is no better example than the remarkable Arvind Gupta (see his TED talk). His philosophy of using toys as thinking aids is very inspiring. Being in Pune, I have had a few opportunities to attend his talks and interact with him (as part of an event at science activity center at IISER-Pune), and I found his approach both refreshing and implementable. Importantly, it also showed me how creativity can emerge from constraints. To re-emphasize this, let me quote APS news article on Andre Geim :

“Geim has said that his predominant research strategy is to use whatever research facilities are available to him and try to do something new with the equipment at hand. He calls this his “Lego doctrine”: “You have all these different pieces and you have to build something based strictly on the pieces you’ve got.””

Now this is an effective research strategy for experiments in India !

Preamble to the discovery of Raman Effect

Today is India’s National Science Day. It celebrates the discovery of Raman effect on 28th February, 1928.

For more details on the discovery of the effect, and various human aspects related to it : you can see my past blogs here, here, here and here.

In this blog, I will briefly discuss about some of the work that directly influenced Raman’s thinking that further led to a remarkable discovery that we know by his name.

All creative pursuits are motivated by ideas from the past. No one gets their ideas in vacuum. All of us are influenced by the information which we perceive and receive. This means consciously or subconsciously the world that we are creating, both in our minds and in reality, is fundamentally influenced by the information in the world.

The discovery behind the Raman effect is no exception to this particular principle. In his formative years, C V Raman was heavily influenced by the research of Rayleigh and Helmholtz, and some classical thinkers including Euclid. Raman was also closely following the development of quantum mechanics in the early 1920s, and he was keenly studying the theoretical and experimental developments in this field.

Two aspects which played a crucial role in motivating Raman’s (Nobel prize winning) work was Compton scattering and Kramers-Heisenberg formula.

Compton scattering was as outstanding experimental achievement that revealed two aspects of light-matter interaction. First, it demonstrated inelastic scattering of electromagnetic radiation interacting with a quantum object (in this case free electrons) in the laboratory frame. Second is that it laid a foundation to revisit the wave-particle duality of light from an experimental viewpoint. Raman and Krishnan’s main paper on light scattering starts by explicitly referring to Compton effect, and motivates observation for optical analogue of Compton scattering.

To quote from Raman’s Nobel lecture :

“In interpreting the observed phenomena, the analogy with the Compton effect was adopted as the guiding principle. The work of Compton had gained general acceptance for the idea that the scattering of radiation is a unitary process in which the conservation principles hold good.”

Next is the Kramers-Heisenberg formula. This mathematical description gives the scattering cross section of a photon interacting with a quantum object (in this case electron). This formula uses second-order perturbation theory, and evokes the famous ‘sum of all the intermediate states’ for non-resonant optical interaction. PAM Dirac played a vital role in deriving this formula from a quantum mechanical framework of radiation. An important and logical consequence of this formula is the emergence of stimulated emission of radiation, and this has had deep implications in understanding LASERs. Raman was keenly studying the formula and made a brilliant conceptual connection between laboratory observation and this formula that revealed the scattering cross-section.

Again to quote from Raman’s Nobel lecture:

“The work of Kramers and Heisenberg, and the newer developments in quantum mechanics which have their root in Bohr’s correspondence principle seem to offer a promising way of approach towards an understanding of the experimental results.”

The above two concepts were important ideas that motivated Raman scattering experiments. Importantly it highlights the jugalbandi between theoretical intuition with concrete experimental observations, which forms the bedrock of modern physics.

Newton famously mentioned about the discoveries he made by ‘standing on the shoulders of the giants’. Various people involved in creative pursuits including scientists acknowledge the fact that new ideas emerge from convergence/mutation of old ideas. The harder part of creativity in science, or for that matter any art form, is to choose the right ideas to combine so that the ’emergent’ new idea has greater value compared to the individual parts. In that sense, science is a great form of creative activity that not only combines old ideas to create new valuable ideas, but also transforms the perspective of the individual seed ideas. Thus ideas combine and evolve.

So let us combine good ideas and evolve. Happy Science Day !

Geo-fractal…somewhere over south India

I am always amazed to see fractal-like patterns….this one at a geographical scale…captured somewhere over south India..

I took the photo on my trip back to Pune from IIT Madras…

Thanks to IIT-M physics department for their invitation for colloquium…

Special thanks to Basudev Roy and Nirmala for hosting…. greatly enjoyed the discussion with many faculties and students..

In my talk, I mainly spoke on topics at the interface of statistical optics, Brownian motion and pattern formation..
Was delighted to see (and meet) Profs. Balki, Suresh Govindarajan Sunil Kumar Arnab Pal and many more in the audience.

The photo, retrospectively, captures the essence of the science discussed…

Soft Matter Optics – talk at ACS -India

About 2 years ago (22nd May 2020), when all the academic activities were online, I gave a talk on “Soft-Matter Optics: A Cabinet of Curiosities” organized by American Chemical Society as part of India Science Talks. Below is the embedded video of the online talk.

Link to ACS website can be found here.

In there, I give a broad overview of how interesting optical function can emerge from the complex world of soft matter. In addition to this, I have emphasized how optics can be harnessed to study structure and dynamics of soft-matter systems including colloids, liquid crystal and some biological matter. The target audience are new PhD students and anyone who is entering the field of light-soft matter interaction.

Indian Philosophy and Independent thought

Today we mark the 75th anniversary of Indian independence from the British colonial rule. For a country of our population and size, it is indeed a great achievement that we have sustained to be a democratic nation. We continue to be a work in progress and there is a lot to learn and look forward to.

India today is awash in the tri-colour flag, which marks a symbol of our identity.

This symbol has a deeper philosophical meaning, and it has been wonderfully described by one of the great Indian philosopher Sarvepalli Radhakrishnan (also first vice-president of India, and subsequently President of India) as follows :

“Bhagwa or the saffron colour denotes renunciation of disinterestedness. Our leaders must be indifferent to material gains and dedicate themselves to their work. The white in the centre is light, the path of truth to guide our conduct. The green shows our relation to soil, our relation to the plant life here on which all other life depends. The Ashoka Wheel in the center of the white is the wheel of the law of dharma. Truth or satya, dharma or virtue ought to be the controlling principles of those who work under this flag. Again, the wheel denotes motion. There is death in stagnation. There is life in movement. India should no more resist change, it must move and go forward. The wheel represents the dynamism of a peaceful change.”

Dr. S. Radhakrishnan, Constituent Assembly of Independent India

The metaphor of wheel to go forward is noteworthy. It essentially states that we as a society should be forward-looking and evolve our thoughts as we make progress. Such a call for evolution of thought and progress is not alien to our civilization.

Lest we forget – Indian philosophy is not just a spiritual literature, it has immense depth and discussion on rationality and logic, and places emphasis on debates and arguments. So much so, that even our great, ancients poets such as Kalidasa uphold this rational spirit in their writings. To quote from his famous Malavikaagnimitram :

पुराणमित्येव न साधु सर्वंन चाऽपि काव्यं नवमित्यवद्यम्।

सन्तः परीक्ष्यान्यतरत् भजन्तेमूढ्ः परप्रत्ययनेयबुद्धिः ॥

-मालविकाग्निमित्रम् (महाकवि कालिदास)

The translation (source) from Sanskrit means :

All poems are not good only because they are old. All poems are not bad because they are new. Good and wise people examine both and decide whether a poem is good or bad. Only a fool will be blindly led by what others say.

-Malavikaagnimitram (Great Poet Kaalidaas)

My hope is that we as a society get inspired by these calls for rationality, and adapt empathy, humility, logical and scientific thinking as some of the core principles our lives. This is not only for a better India, but also for a better world.

After all, as one of ancient Indian philosophical text (Maha Upanishad, 6.71–75) says :

अयं निजः परो वेति गणना लघुचेतसाम्!!

उदारचरितानां तु वसुधैव कुटुम्बकम् !!

which is transliterated as :

This is mine, that is his, say the small minded,

The wise believe that the entire world is a family.

Dear Indian people….Happy 75th Independence Day !

Talks on C.V. Raman – YouTube links

Below are the YouTube links to the 2 talks I gave on C.V. Raman on the occasion of India’s Science Day

The first talk is about : C.V. Raman: A brief History

Organized by IISER Pune Science Activity Centre
Age group 6 to 100: Students, Teachers, Science Enthusiasts and all Members of the Public

The second talk is about : C. V. Raman : History of Ideas

Organized by Science Club IISER Pune

Target audience: Science students and researchers

Announcement: my webinars on Science Day

This year, on India’s Science Day – 28th Feb, I will be giving 2 webinars

1)9:45 AM to 10:15 AM:
C.V. Raman: A brief History

This is a pre-recorded talk

Organized by IISER Pune outreach.
IISER Pune Science Activity Centre
Age group 6 to 100: Students, Teachers, Science Enthusiasts and all Members of the Public

2) 6pm – live talk
C. V. Raman : History of Ideas

Organized by Science Club IISER Pune

Target audience: Science students and researchers

Zoom Link:

Probably, these talks will be put on YouTube too. I shall post the links when available