Posts Tagged ‘thermodynamics’

Paul Davies’ The demon in the machine

July 3, 2020

The book The demon in the machine by Paul Davies won the Physics World book of the year in 2019; after listening to the podcast, I decided to give it a try. I am glad I did. This is one of the best books of popular science that I have read and enjoyed in the recent past. Before I go on rambling in the rest of this post, strongly recommended. Do buy it and read it.

Thermodynamics has always been a fascinating subject. During my undergraduate years, a couple of us spent lots of time trying to read some of the thermodynamic classics in the original (and translations into English when it was not in English). It did not help us score well in the examination. But, it did keep the interest in the subject alive.

During my Masters, when the instructor talked about Shannon and his information entropy I was intrigued; but at that point I could not understand the nuances; I kept wondering how the manner in which we decide to represent information can have any entropy; I did ask him for some explanations; he did supply some; but I was not scientifically mature enough to follow the arguments. This was also the time when I read some popular pieces about Maxwell’s demon in the Hindu science page.

When I was completing my Masters and embarking on the second, I came across Schroedinger’s What is life. It is one of the books that influenced me a lot. I did not carry much from the book about life. But, the idea that molecules and solids are qualitatively the same is the one big idea that I carried from the book. The second one was the dictum that “Living matter evades decay to equilbrium”, of course!!

But, with all the nanotechnology hoopla, I still never made the connection to What is life and the treatment of molecules by Schroedinger. Somewhere, I once read that nanotechnology is useful as a study to understand the fundamentals of materials phenomena and is useful in applications in medicine and military where the costs are not a concern; I took it to heart. I should have paid more attention and should have connected to molecules as precursors to solids.

I also did not do much of follow-up reading on What is life. Even though I did keep in touch with thermodynamics, Maxwell’s demon and Szilard’s engines remained just some esoteric topics in thermodynamics for me.

Here is a book which brings together all these ideas — life, information, Maxwell’s demon, and nanotechnology with quantum mechanics, for a good measure, thrown in and out of this mix comes the remarkable ideas, speculations and concepts about life and information flows. There are interesting molecular machines and the remarkable ways in which they work the second law to their advantage.

There is also the fascinating fact that life’s machines work well in a narrow range and achieve quite a bit of efficiency compared to mechanical engines that we build which achieve higher and higher efficiencies only when operated at higher and higher temperature differences. I have heard from a colleague that this aspect of biological systems used to excite Professor C V Seshadri and I understood the technical details of this process by reading this book.

So, if you are looking for a good science-y read, here is a book which will not fail you! In fact, reading the book made me put together a more serious reading list with lots of papers and articles — from Scientific American to Physical Review and I am looking forward to reading all of them!

Once again, strongly recommended. Have fun!!

Peter Atkins’ Four laws that drive the universe

November 23, 2008

I finished reading Peter Atkins’ Four laws; I enjoyed it a lot, and I have no hesitations in recommending it. I hope OUP publishes a low priced, paperback edition so that many more students will have access to this wonderful book.

Be it the very first sentence in the book

The zeroth law is an afterthought

which reminded me of some good openings of certain mystery novels, or the interesting pieces of information (as, for example, that in the original Celsius scale, water froze at 100 and bolied at 0 degrees Celcius), or the deep concepts explained in a rather lucid fashion (like the section on Fluctuation-Dissipation theorem on page. 42), or the new aspects of looking at thermodynamics that the book introduces (for example, as to why Boltzmann constant is not to be considered a fundamental constant but a conversion factor), I never found the book dull (though, at times, I did find it to be very engrossing and a bit time-consuming to go through the arguments).

Overall, I also think that the approach used by Atkins, namely

… we consider first the observational aspects of each law, then dive below thhe surface of bulk matter and discover the illumination that comes from the interpretation of the laws in terms of concepts that inhabit the underworld of atoms[.]

is very natural and effective; concepts like energy, entropy, temperature, enthalpy, and Helmholtz and Gibbs free energies are explained by Atkins using this approach; and, by far, these are some of the best explanations that I have seen.

Let me end this post by quoting Paul Davies from the blurb of the book,

Arkins is a master expositor, who combines penetrating insight with simplicity of style and a gentle elegance.

Hunt for the book in your library; or, better still, buy yourself a copy and have fun!

PS: By the way, here is an YouTube video wherein Atkins introduces the book.

Note to self: At least a couple of books from Atkins’ Further Reading list sound interesting: G N Lewis and M Randall, Thermodynamics and B Widom, Statistical Mechanics: a concise introduction for chemists.

PS 2: Thanks to my colleague Rajesh for introducing the book to me, and agreeing to part it for the last one month. I hope to get a personal copy for myself soon.

Molecular machines and their operation

December 11, 2007

An interesting paper in the latest issue of PNAS titled Adiabatic operation of a molecular machine by R Dean Astumian:

Operation of a molecular machine is often thought of as a “far from equilibrium” process in which energy released by some high free energy fuel molecule or by light is used to drive a nonequilibrium “power stroke” to do work on the environment. Here we discuss how a molecular machine can be operated arbitrarily close to chemical equilibrium and still perform significant work at an appreciable rate: micrometer per second velocities against piconewton loads. As a specific example, we focus on a motor based on a three-ring catenane similar to that discussed by Leigh [Leigh DA, Wong JKY, Dehez F, Zerbetto F (2003) Nature 424:174–179]. The machine moves through its working cycle under the influence of external modulation of the energies of the states, where the modulation is carried out slowly enough that the state probabilities obey a Boltzmann equilibrium distribution at every instant. The mechanism can be understood in terms of the geometric phase [Berry MV (1990) Phys Today 43(12):34–40] in which the system moves adiabatically around a closed loop in parameter space, completing, on average, nearly one-half mechanical cycle each time it does so. Because the system is very close to equilibrium at every instant, the efficiency can approach 100%.

Sounds interesting; take a look!

Some more thermodynamics

October 8, 2007

Didn’t I tell you about the bit of thermodynamics in every researcher’s life? Rajeev, at his Almanack, writes about the geometry of thermodynamics, the close analogy between thermodynamics and geometric optics, and geometrisation of thermodynamics as the first step towards quantum thermodynamics. What is more, the hero of the piece is none other than Gibbs (with S Chandrashekhar also being part of the cast):

… the main problem I had was to find out information about good old fashioned classical thermodynamics. Except for some treatments by V. I. Arnold and Chnadrashekhar, I had to go all the way back to the literature of almost a hundred years to find a sophisticated discussion on the subject. J. W. Gibbs is the main hero of the story, his ideas were developed by Pfaff and Caratheodory into a beautiful if under-appreciated subject.

Take a look!

A bit of thermodynamics

October 3, 2007

Steel Authority of India Limited used to run a campaign with the slogan “There is a bit of SAIL in everybody’s life” (and the one I remember vividly is that of a housewife with a steel key tied to her saree end). Same can be said of thermodynamics — there is a bit of thermodynamics in every materials researcher’s life. And, lest I forget, there is thermodynamics and thermodynamics (as the spirited discussions in this iMechanica post shows). Here are a couple of links (which, by the way, also indicate the range and richness of the field).

  • In This week in cond-mat series, Doug at Nanoscale views writes about a couple of papers: Violation of Wiedemann -Franz law in single electron transistors, and another on quantum heat engines (and, yes, they do obey Carnot’s theorem).
  • More closer to the thermodynamics in my research life is the on going journal club discussion at iMechanica on Irreversible thermodynamics of continuous media. Anurag, the moderator of the discussions, refers to a couple of books, which I have not read. However, I did read Silhavy’s The mechanics and thermodynamics of continuous media on the recommendation of my continuum mechanics instructor (and, found it very nice too).

    Anurag, then proceeds to recommend a couple of papers for spatial pattern formation on systems that are far from equilibrium — that of Prigogine, and Cross and Hohenberg. I have not read the papers of Prigogine. But, I have lots to say about the review article of Cross and Hohenberg; I probably will do a couple of posts in the near future.

    Anurag ends the post with links to a couple of papers on plastic evolution — that of Bridgman and Hartley. Again, this is an area that is just at the periphery of my research interests. So, I might do a post on these, but not in the immediate future. In the meanwhile, have fun at iMechanica, where there is also plenty of discussions.

Happy reading!