Kathy Joseph’s Video Essays on Early History of Thermodynamics

Thanks to Doug Natelson, I discovered Kathy Joseph’s YouTube channel on history of physics; here’s her website, Kathy Loves Physics.

Kathy’s video essays are very good at narrating how hunches, premonitions, and proto-ideas (triggered by interesting / new empirical observations) evolve into fully crystallized concepts that we now teach. Along the way, Kathy spices up the narrative by giving us a sense of the scientists’ personal histories and their social and political environment.

I went through her video list, and decided to check out her series on the development of thermodynamics, and spent the next 75 minutes or so listening to the fascinating life stories of concepts such as work, heat, energy, and entropy.

She starts the series at an odd place: the Third Law, Walter Nernst, the 1911 Solway Conference, and how Albert Einstein came to be among the invitees.

I’ll just give the links to the videos in this series (about 75 minutes in all):

How the 3rd Law of Thermodynamics Made Einstein Famous (embedded above).

How the Laws of Thermodynamics Ended Up in “The Wiz”.

First Law of Thermodynamics: History of the Concept of Energy.

Entropy: Origin of the Second Law of Thermodynamics.

And, finally, Boltzmann’s Entropy Equation: A History from Clausius to Planck.

Highly recommended.

DIY Crystal Growth Videos

Here’s a very good example that shows the process of producing single crystals and polycrystalline aggregates of copper sulphate. They are so good looking that they can serve as decorative pieces in your living room! [Check out the creator’s channel for more such videos.]

The next one is a time lapse video of growing crystals (of a variety of materials; this genre of videos are their own art form!

What is hidden in these short videos is the tremendous amount of patience and diligence required to get high quality results. In the first video, for example, you see instructions about filtering the solution every day, and keeping the beaker undisturbed, and waiting for 2 weeks or more.

Surface Tension

What a brilliant video! In just 30 minutes, Prof. Lloyd Trefethen (Wikipedia) of Tufts University manages to cover a huge variety of phenomena that arise due to surface tension: capillary rise, nucleation, Rayleigh instability, effects due to a chemical, temperature and charge gradients) using excellent demonstrations (some of which are in slo-mo). Explaining and presenting an analysis of these phenomena / effects in an undergrad curriculum could take 5 hours or more!

Of particular interest to materials is the section (at ~4 minutes) in which Prof. Trefethen derives the Young-Laplace equation (in less than 30 seconds!), and another (at ~2 minutes) in which he demonstrates the symmetry that arises when three bubbles meet at a point such that two bubble walls form 120^o; immediately after this demo comes another showing that 4-bubble meetings are unstable in 2D.

Lecture on Perovskites by Mike Glazer

Yet another gem from the Royal Institution: the 2017 Bragg Lecture by Mike Glazer entitled The Wondrous World of Provskites.

He covers a fair bit of ground here: some personal history (including a wonderful anecdote about one of his mentors, Prof. Helen Megaw), some elementary crystallography (unit cells, symmetry, and stuff), how solid state chemists have a way of bringing a wide variety of structures under a common umbrella (octahedrons sharing corners), some interesting properties (pyroelectricity, piezoelectricity, photovoltaics, …) and applications (for temperature changes, tennis rackets, solar cells, SONAR, ultrasound scans, …). In between all this, you also get glimpses of phase diagrams, defects, intrinsic and extrinsic properties, and materials design. It’s a fascinating tour. [RI has also released a video of the Q&A session.]

Floating Shadeballs and 2D Crystals

Here’s a fascinating video from Veritasium’s Derek Muller about the use of a bunch 10-cm dia balls — actually, 96 million of them! — covering the surface of a huge lake. The purpose: to prevent (or, minimize) sunlight-enhanced chemical reactions that produce harmful stuff in water in storage reservoirs in Los Angeles.

One of the notable things in the video is the appearance of 2D-crystallite-like features that these creatures create on the reservoir surface. There are localized pockets of crystalline arrangement of these macroscopic objects, and we can even sense features resembling grain boundaries; I’m sure there are vacancies and dislocations in there if we get to see the details of the crystallites. [These features are somewhat clearer in Muller’s second video of shadeballs floating in his swimming pool.].

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Solidification of Sodium Acetate at Room Temperature

Yet another video demo — this one on solidification of sodium acetate.

From the Wikipedia entry on this compound, we learn what’s going on (and also about how this phenomenon makes it suitable for applications such as hand warmers and heating pads):

Sodium acetate is also used in heating pads, hand warmers, and hot ice. Sodium acetate trihydrate crystals melt at 136.4 °F/58 °C (to 137.12 °F/58.4 °C),[14] dissolving in their water of crystallization. When they are heated past the melting point and subsequently allowed to cool, the aqueous solution becomes supersaturated. This solution is capable of cooling to room temperature without forming crystals. By pressing on a metal disc within the heating pad, a nucleation center is formed, causing the solution to crystallize back into solid sodium acetate trihydrate. The bond-forming process of crystallization is exothermic.[15] The latent heat of fusion is about 264–289 kJ/kg. Unlike some types of heat packs, such as those dependent upon irreversible chemical reactions, a sodium acetate heat pack can be easily reused by immersing the pack in boiling water for a few minutes, until the crystals are completely dissolved, and allowing the pack to slowly cool to room temperature

Superconductor Gliding along a Magnetic Möbius Strip

This very informative (and beautiful)) video from the Royal Institution (starring Andy Mermery) has a cool demo on the repulsive force experienced by a magnet when it is moving near a conductor (or a conductor moving near a magnet). Since force can be made stronger if the resistance in the conductor is brought down, Andy takes a piece of high-Tc superconductor (yttrium barium copper oxide) and lets it glide (and be guided) on a track made with powerful neodymium-based magnets on both sides of a Möbius strip. Andy also explains the piece stays “locked” to the track irrespective of whether it is above or below the track; the currents set up in the piece due to its relative motion with the magnet produce forces that oppose that motion.

Lecture on 100+ Years of X-Ray Crystallography

This YouTube Video (also embedded below) of Prof. Stephen Curry’s lecture at the Royal Institution is absolutely fantastic. The lecture was delivered in 2013 to celebrate centenary of the discovery of X-ray crystallography. [I guess this was a prelude to the year 2014 being celebrated as the International Year of Crystallography].

In just over 60 minutes, Prof. Curry covers pretty much all the key developments in 100+ years of X-ray Crystallography; he makes effective use of nifty demonstrations (the one with light going through 1, 2, … 6 slits is particularly nice) and informative animations (the one that demonstrates why even the slightest of deviation from the Bragg condition leads to zero intensity). Also, he does not shy away from presenting complicated concepts (such as Fourier Transforms) using a simple (but non-condescending) language.

Finally, the mild bits of humour peppered throughout the lecture are a big bonus!

Nobel Prizes and X-Ray Crystallography

The Wikipedia entry on X-ray crystallography has a list of Nobel Prize winners whose work relied on this technique. The early Prizes — for Max von Laue (1914) and the father-son duo, W.H. Bragg and W.L. Bragg (1915) — were in Physics, while that for Watson, Crick and Wilkins (1962) was in Medicine; all the other Prizes were in Chemistry, with the most recent being in 2012.

Light interference from 2, 3, …, 7 slits

This video (also embedded below) is pretty neat. I find it amazing that at just 7 slits, we get regularly spaced spots — almost what one would get from a diffraction grating with many slits.

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This video, on the other hand, shows interference patterns that arise when light goes through objects such as a comb, a spring, two combs, etc. Three is no accompanying commentary, though! But the results are mesmerizing.

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