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.

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
https://www.iiserpune.ac.in/events/3430/national-science-day-2022

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

Organized by Science Club IISER Pune

Target audience: Science students and researchers

Zoom Link: https://zoom.us/j/91706756774?pwd=Q3lLOXB3ODVnZHd0ZVJaTWc4QjFoUT09

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

Open-access publishing is not so open

https://www.nature.com/articles/d41586-022-00342-w

This is so obvious to Indian research community… open access is open only to the readers, not to the authors from low and lower-middle income countries such as India

Above article in nature reinforces this point.. with a data backed reference

64. Susskind’s view on philosophical Feynman

Since my student days, I have been studying various things Richard Feynman wrote. His 3 volumes of lectures in physics have been one of the ‘go-to sources’ on basic physics. I have also enjoyed reading his lectures on advanced topics, including nanotechnology and computing. Apart from all this, I have also been impressed by Feynman’s viewpoint on science, society and human living.

In the passing, I have read that he did not like philosophers, but I always felt that Feynman’s thoughts were deeply philosophical without the frills of sophisticated language.

Recently, I came across a wonderful conversation with Leonard Susskind, a close friend of Feynman and an accomplished physicist himself. In this video (around 40.18 min), Susskind highlights that Feynman was deeply philosophical. He emphasizes that Feynman did not like the way philosophical discourse was conducted, especially in the context of the philosophy of science. This point kind of reinforced my impression of Feynman and was heartening.

I admire Feynman for making science interesting, but I am also very well aware that Feynman has been criticized for being sexist. Feynman was a scientific genius, but he had his flaws.

Anyway, the whole conversation with Susskind is educative. The best part is when he talks about why he likes teaching (around 1.06 hours in the video), which is worth watching.

63. Pattern formation in my kitchen

If you allow oil to diffuse through a patterned paper napkin on a plate, you can print that pattern on most of the dry plates in a kitchen ( steel plate in this case). In the image, the darker regions are oil soaked, and the ligher circular regions are devoid of oil. Essentially, the patterns are evident due to contrast in refractive index

61. Free e-book on Discovering Light: Fun Experiments with Optics

Linked is an open-access, e-book released by  SPIE, OSA et al.,

“Discovering Light: Fun Experiments with Optics”

Topics are very interesting…look forward to reading it..

https://www.spiedigitallibrary.org/ebooks/PM/Discovering-Light-Fun-Experiments-with-Optics/eISBN-9781510639362/10.1117/3.2579764?SSO=1

Enjoy !

59. Who is a physicist?

“The physicist is most cogently identified, not by the subject studied, but by the way in which a subject is studied and by the nature of the information being sought.”

Above is an interesting quote by Sol Gruner, James Langer, Phil Nelson, and Viola Vogel from a 1995 article in Physics Today titled WHAT FUTURE WILL WE CHOOSE FOR PHYSICS?

Although written more than 25 years ago from the viewpoint of US physics community, many of the issues discussed in this article are pertinent even today. Probably more so in the Indian context.

Nice read :

What Future Will We Choose for Physics?
Sol M. Gruner, James S. Langer, Phil Nelson, and Viola Vogel
Citation: Physics Today 48, 12, 25 (1995); doi: 10.1063/1.881477
View online: https://doi.org/10.1063/1.881477

58. Optothermal Pulling of colloids using Nanowire Plasmons – my talk at Compflu 2021

Linked is my recorded-talk presented at Compflu 2021 today (13th Dec) in the session : Active and Living Matter.

I discuss our recent work on optothermal pulling, trapping and assembly of micro-colloids under the influence of thermoplasmonic field of a single silver nanowire.

The talk was recorded on 2nd Dec 2021, so the reference on conclusion-slide is not updated.

57. Single nanoparticle driven thermoplasmonic tweezer : single-molecule SERS

We have a new paper published in Journal of Physical Chemistry Letters on “Single Molecule Surface Enhanced Raman Scattering in a Single Gold Nanoparticle-Driven Thermoplasmonic Tweezer”

Thanks to the fantastic effort by Sunny Tiwari, and excellent support by Utkarsh Khandelwal (former IISER-P undergrad) and Vandana Sharma from my group, we have been able to combine single molecule Raman scattering with a specialized nanoscale optical tweezer.

The uniqueness of this tweezer platform  is that the optical trapping process is driven by the thermo-plasmonic potential created by a SINGLE, 150nm GOLD NANOPARTICLE. Concomitantly, the same field can be used to perform single-molecule Raman spectroscopy. Kind of  “ek teer mae do shikar” strategy Smile

Using this system, not only we push the limits of optothermal trapping of a single nanoparticle (see video) at low laser powers, but also create a platform for deterministic transport of reversible colloidal assembly in a fluid.

We envisage that our nanometric plasmonic tweezer can be harnessed to trap and tweeze biological entities such as single virus and bacteria. Another possible application of our study is to create reconfigurable plasmonic metafluids in physiological and catalytic environments, and to be potentially adapted as an in vivo optothermal tweezer.

All the videos related to this study can be found on our lab’s Youtube channel : https://www.youtube.com/playlist?list=PLVIRTkGrtbrvs7BaNsaH6tjPpzLUizyMI

DoI of the published paper : https://doi.org/10.1021/acs.jpclett.1c03450

preprint version on arxiv : https://arxiv.org/abs/2109.04281