55. Kindness in science

There is absolutely no conflict between doing good science and being kind to people with whom you work, and this includes not only colleagues and students, but also administrative staff and everyone in an academic ecosystem. The below linked article makes a good case for this point.

It also derives some relevant lessons from philosophy which can be applied to academic environment. Worth reading…if you have access

https://www.cell.com/trends/cell-biology/fulltext/S0962-8924(21)00229-4

54. End-sem email to my class

Below is an email I sent to my introductory-optics class of 77 students (third-year undergraduates) on the final day of my course, which was today. Although the course was completely online, I did enjoy interacting and discussing with them on various topics on optics and photonics.

———————

Dear All,


Today is the final day of the optics course – PH3134, and I hope all of you have gained some knowledge from the online interaction we had over the past months. 


Optics is one of the most fascinating areas of science, and historically one of the oldest topics in physics. Yet, it continues to throw new surprises in contemporary research. I hope some of you will pursue research in optics and related areas. Even otherwise, do remember that optics plays a vital role in understanding and implementing various aspects of science and technology. Its relevance has remained high for centuries, and will remain so for the foreseeable future. 

I know many of you are at home, and conditions are not ideal for studies. So, thank you for keeping up your interests even during these tough times. I highly appreciate it.


An important take away for me as a teacher/researcher (from every course I teach) is that what we have discussed and studied is just a metaphoric drop in a mighty ocean of knowledge. That means there is a lot to learn for all of us. Do keep learning beyond the coursework. There is no limit for that.


Light up the world !

best wishes,

Pavan

53. Karnad’s preface to his memoir

One of the important aspects of reading a preface to a book is to know why an author wrote that book. This is one place where authors freely express their opinion on various things, and sometimes this opinion is not necessarily related to that book. For me, reading the preface connects me to the author in a better way than say, reading a review of the book, which I generally do after reading the book. Over the years, I have made it a habit to read the preface of almost any book I have come across.
In this context, recently I came across one of the most hilarious prefaces I have read. This is from Girish Karnard‘s memoir (translated from Kannada) titled : this life at play.


Below I reproduce the preface (which is by the way, available online) :

Dharwad, 1973

Aayi (my mother), Bappa (my father) and I were having lunch. My first film Samskara had won the President’s Gold Medal. My second, Vamsha Vriksha, had had a successful run and won the National Award for best direction. My latest film Kaadu was in the final stages of production. I was a Sangeet Natak Akademi awardee. And I had just been named the director of the Film and Television Institute of India. The air at home was thick with self-congratulation.

Then Aayi looked at Bappa and said, ‘And we had thought of not having him.’Bappa went red in the face. After some stammering, he managed to say, ‘That was all your idea, not mine. Why bring this up now?’ and hid his face in the plate in front of him.

I had to know more. I asked Aayi, and she explained: ‘I had three children already when I became pregnant with you. I thought that was enough, so we went to a doctor in Poona named Madhumalati Gune.’

‘And?’

‘She had said she would be at the clinic, but she wasn’t. We waited an hour and returned.’

‘And then?’

‘And then, nothing. We never went back.’

I was stunned. I was then thirty-five years old. Still, I grew faint at the possibility that the world could have gone on without me in it. For a while, I sat there unaware of my surroundings, considering the idea of my non-existence. A thought struck me. With some bewilderment, I asked about my younger sister: ‘Then, what about Leena…?’

Aayi said, somewhat coyly, ‘Oh, we had stopped thinking of all that by then.’ She burst out laughing. Bappa remained engrossed in the contents of his plate.

Had the doctor arrived at the clinic as promised, these memoirs and their narrator would not have existed. So, I dedicate this autobiography to the memory of the person who made all this possible: Dr Madhumalati Gune.

Girish Karnad

Bangalore, 19 May 2011

52. Optothermal pulling and trapping..with nanowire plasmons

We have a new paper published in the journal ‘Soft Matter’ titled : Optothermal pulling, trapping, and assembly of colloids using nanowire plasmons

When a silver nanowire is optically illuminated under certain conditions, they propagate surface plasmons. These surface electromagnetic waves not only propagate light at subwavelength scale, but also generate heat along the nanowire.

A question of interest to us: can we use the quasi one-dimensional optothermal potential of a nanowire-plasmon to trap and assemble soft, microscale matter ?

Motivated by this question – Vandana, Sunny and Dipta from my research group, performed optical trapping based experiments to show an interesting pulling and trapping effect on dielectric colloids (see video). Furthermore, by increasing the concentration of the colloids, an emerging two dimensional crystal was observed. Interestingly, the formation of this two dimensional assembly was found to be sensitive to the optical polarization at the excitation point on the nanowire.

Thanks are also due to other co-authors: my colleague Vijayakumar Chikkadi and his student Rathi for helping us to implement the particle tracking code on python.

Optical trapping and tweezing is a fascinating area of research. By adding plasmons to the mix of things, these optical effects become intriguing. Importantly, they facilitate a platform to explore questions in non equilibrium statistical mechanics including optically driven active matter…

Afterall, more is different…

DOI of article : https://doi.org/10.1039/D1SM01365C

Link to arxiv preprint: https://arxiv.org/abs/2109.09557

All videos here :

51. A case for Science + Philosophy

Linked below is an interesting article written by a Phd student.

I am glad to see a research student writing about it, and importantly it appreciates the diversity of thought, and ends well with a disclaimer.

“My background, and therefore my suggestions, are mainly rooted in the Western tradition, but I aim to continue diversifying my education.”

In my opinion philosophy is a subject that ‘many’ scientists are reluctant to entertain, and sometimes are dismissive of it. Many of the great ones, including Feynman and Weinberg have criticized it. (If I’m correct, Einstein was not one among them)

But, with the emergence of technology such as artificial intelligence, machine learning, genetic engineering and stem cell research, philosophical questions become important. Even otherwise, asking philosophical questions about any work helps us appreciate aspects such as: what it is to do work and how our scientific thought and expression interacts with the external world. In a way it is path to self realization.

I am no way dismissing the criticism of great scientists, who may have had a valid point in how philosophical enquiry is conducted. But I think it is not prudent to just discard a school of thought that lays the foundation of how humans think and evolve.

It is important for us to appreciate that Manhattan project was a remarkable scientific achievement, but the consequences had deep and disastrous societal implications. In my opinion what was badly missing there was deeper philosophical enquiry. In an essence, it was a collective human failure, where science was right, and the philosophy was wrong.

Philosophical enquiry not only helps in the evolution of science, but also helps in understanding its interface with societies. And, as we know, how science interacts with western and eastern society can have different consequences.

The case in point is the business of science tuitions in India, and the emergence of online educational platforms which are worth a billion dollars or more. Remember that the science which is been taught in these online tuitions is essentially  the same across the globe, but how the society consumes, and for what reason, is very different.
On the same footing, it also says why so many Indians are attracted to godmen and there unscientific thought processes. It may be because people may have got only the scientific, utilitarian aspect of the knowledge, but not the philosophical component. In this case the concept of critical thinking, which is by no means alien to the eastern philosophy, has been lacking  in the mix of things. As an Indian society, with the rich tradition of debate and discussion, we cannot afford to lose this culture.

This is where philosophy matters : western, eastern, and their combinations.

It is important for us, humans, to combine science with philosophy. Otherwise, science will be an ill defined vector :  large in magnitude without any direction.

https://t.co/K709wf9zAL

50. Nanowire-nanoparticle Raman Antenna

We have a new paper in J. Optics (IOP)

Mirror enhanced directional out-coupling of SERS by remote excitation of a nanowire-nanoparticle cavity

Sunny Tiwari Adarsh Bhaskara Vasista Diptabrata Paul experimentally show how a nanowire-nanoparticle junction placed on a gold mirror can lead to extreme directionality in Raman emission

https://doi.org/10.1088/2040-8986/ac2dd8

Arxiv : https://arxiv.org/abs/2104.13121

49. Optical Spin in Nanowire Plasmons

image

We have a new paper to appear in Applied Physics Letters

The work is about “Experimental observation of transverse spin of plasmon polaritons in a single-crystalline silver nanowire”

Circularly polarized laser beams carry spin angular momentum. Such “spinning” photons have a plethora of applications including optical spanners, optical information processing, chiro-optics, micro-gyroscopes, nonlinear dynamics of matter at micro and nanoscales, and many more.

An interesting question to ask is : can we generate spin states with surface electromagnetic waves such as surface plasmon polaritons ? Unlike freely propagating optical laser beams, surface electromagnetic waves can be harnessed for sub-wavelength optical interaction on a chip, and have risen to importance.

In this paper, we experimentally show how transverse spin can be generated by nanowire surface plasmons. Thanks to the outstanding effort of my group members Chetna Taneja and Diptabrata Paul, we were able to image and measure the spin density of such (quasi) one-dimensional  surface electromagnetic waves in a single-crystalline silver nanowire.

A prospect that we are interested in is to transfer this spin angular momentum to objects such as  individual nanoparticles and molecules in a trap, which can, hopefully, create some interesting (nonlinear) dynamic states.

preprint version on arxiv : https://arxiv.org/abs/2104.09303


48. Test Match Cricket and Research

My favourite sport to watch is test match cricket. It has the ebb and flow of a long drawn, thoughtful contest where temperament is as important as skills. This was evident in the century innings of Rohit Sharma. Although I could not watch the innings live, I did catch up on the highlights, and as expected Rohit’s batting was sublime.

In limited over cricket, Rohit is undoubtedly one of the most accomplished batter ever, with two double centuries in one day internationals. He also is one of the most stylish batter who can score runs on any continent. Unfortunately, he has not accomplished the same reputation in test match cricket. But in the ongoing tour of England, there are some interesting developments. He has taken the initiative to stay at the crease for a long period, and has tightened his game which has let him to score runs as an opener. Mind you, opening batting in overcast English conditions is never an easy task, and it is a remarkable achievement that he has been able to do so with reasonable success.

Coming back to yesterday’s innings Rohit occupied the crease for more than five hours, and played out more than 200 balls, which does require skill and concentration. This undoubtedly lead to fruitful result in him scoring 100. What more, his first hundred overseas came up with a spectacular six.

Now, what lessons, especially in the context of research, can we extract from Rohit success in England?

First and the foremost is the consistency. Many a times, in research, good ideas emerge after consistently working on a particular area. A quote attributed to Linus Pauling puts it well on the lines : “to have a good idea you need to have many ideas”. Rohit has been playing for a long time, and his experience has indeed helped him to adapt on this tour to be consistent.

Second, no matter how skilled or talented you are, you cannot accomplish big things without the right temperament and perseverance. Research and test match cricket is very similar in that way. Compare Rohit’s limited over cricket record versus the test record.

Third, there is enough room in the chosen area of research to be creative. All researchers need not do the same kind of work, and there is enough room for individuality in the kind of research one can do. Rohit doesn’t play like Virat or Pujara, but still contributes in his own way.

Finally, the right ecosystem to flourish. Generally in research, the most important aspect is the people – students, colleagues and staff. Next comes the infrastructure and funding. The order that I have chosen to mention this is deliberate, because having the right people, with right mindset, is more important than having more money. Indian cricket has always been quite rich in finances, but over the last 15 years or so, a lot of professional people, like Dravid, have taken up the supporting rule, which has made a positive difference.

Whether India will win the series or not, we will have to see. But the fact that even during the pandemic we are entertained with high quality test match cricket is a tribute to the sporting spirit of the players. In many ways, it also motivates us to do good research.

Long live test match cricket !

47. Nagendra, Weinberg and some memories…

IIA days…

It was late summer/early monsoon season of 2003, in Bangalore. The BTS bus travel from Rajajinagar to Koramangala via Majestic used to take 90 min or more. This commute, which I did for about 2 to 3 months, as summer student at Indian Institute Astrophysics (IIA) is still etched in my memory. I had just finished my first year MSc (Physics), and was seriously hooked on to physics in general, and astrophysics in particular. My summer project was on second solar spectrum guided by Prof. K. N. Nagendra (KNN) at IIA. It was he who introduced me to the fabulous world of polarization optics in the context of solar physics. This opened my eyes to the spectacular world of photon transport through an inhomogeneous medium, and hence multiple scattering of light. It was KNN who also introduced me to the classic : Radiative Transfer by Subrahmanyan Chandrasekhar. My first task as a summer student was to read the first chapter of this book and understand the representation of polarized light using Stokes parameters. The summer of 2003, was also the first time I encountered the power of computational methods to solve scientific problems, and ever since then I have deeply appreciated the role of computers in solving scientific problems. This introduction to computational physics and polarization optics (in the form of Jones, Stokes and Muller matrices) has turned out to be an important concept which I still use in my research. I thank KNN for this.

Recently, I was shocked to know that Prof. KNN passed away. His death was untimely, and a very sad news to me and many of the people who knew him. My condolences to his family, friends and students.

Weinberg inspires…

Recently, I also came to know about the sad demise of Steven Weinberg. Thanks to a special paper on Introduction to Quantum Electrodynamics in the final semester of my MSc, I learnt a bit about Weinberg as we were introduced to some aspects of unification of weak and electromagnetic forces. Also, with great enthusiasm, I learnt a lot from his fascinating book : The First Three Minutes: A Modern View of the Origin of the Universe. Undoubtedly, the scientific world has lost a great thinker.

The greatest impact of Weinberg on me was in a different context. In summer of 2004, I was selected for a PhD position at JNCASR. Prof. Chandrabhas had agreed to take me in as a PhD student, and I was elated and excited to join his group. I still remember the first time I visited his lab (after the selection) sometime in late May or early June 2004. As I entered the lab and opened that famous sliding door, there was a print-out of an article which was pasted right beside the door. This article was the Four Golden Lessons by Steven Weinberg, which was then recently published in 2003. This was literally, the first article I read as a PhD student in the lab, and has deeply impacted my work.

I still revisit the four golden lessons, time and again, and has been extremely useful throughout my career. As a tribute to him, below I reproduce the third lesson, which I think is worth contemplating :

My third piece of advice is probably the hardest to take. It is to forgive yourself for wasting time. Students are only asked to solve problems that their professors (unless unusually cruel) know to be solvable. In addition, it doesn’t matter if the problems are scientifically important — they have to be solved to pass the course. But in the real world, it’s very hard to know which problems are important, and you never know whether at a given moment in history a problem is solvable. At the beginning of the twentieth century, several leading physicists, including Lorentz and Abraham, were trying to work out a theory of the electron. This was partly in order to understand why all attempts to detect effects of Earth’s motion through the ether had failed. We now know that they were working on the wrong problem. At that time, no one could have developed a successful theory of the electron, because quantum mechanics had not yet been discovered. It took the genius of Albert Einstein in 1905 to realize that the right problem on which to work was the effect of motion on measurements of space and time. This led him to the special theory of relativity. As you will never be sure which are the right problems to work on, most of the time that you spend in the laboratory or at your desk will be wasted. If you want to be creative, then you will have to get used to spending most of your time not being creative, to being becalmed on the ocean of scientific knowledge. (emphasis is mine)

Thank you, KNN and Weinberg…for some golden lessons…