Friday, May 17, 2013

Notes from the Scientific Literature: Thermal Conductivity and Making Connections


When I was an undergraduate and graduate student I had plenty of time for deep scholarship: e.g. the time to go through volumes of Proc. Roy. Acad. Sciences in ~ 1922 to see what scientists were up to during those heady times in the early days of the new physics, and also read carefully through every paper on high pressure mineral physics. But then came postdoctoral positions simultaneously with new baby followed by long years of assistant professor-hood coupled with continuing mom-dom, and it was all I could do even to mess-up the references for papers and proposals.

Now that I’m finishing off the last few forkfuls off those pie-slices, I’m pulled back to the deep literature. I am working on a paper on thermal conductivity at high pressures and high temperatures, and am going back 100 years to the early thermal conductivity literature. The field of thermal conductivity of insulating materials is lucky to have had the master synthesizer P.G. Klemens, who escaped from Nazi Germany with his family, was educated at Oxford—the postwar center for thermal conductivity studies—and then came to the US to work first on proto-“Star Wars” development and then the chair of the physics department at UConn. (I have stories about that department, but those are for another time&place.)

Prof. Klemens (d. 2002) left behind a beautifully clear series of review papers, which not only summarize the science of thermal conductivity of insulating materials, but also lay out the history of discoveries while placing them in context of the concurrent big questions that were intriguing physicists—questions of kinetics, particle momentum, anharmonicity—all of these things and more. 

When I get to the review-paper stage of my career, I hope to emulate Klemens.

In those early days of scientific learning, I just attempted to soak it all in. I remember when the thermodynamics I was learning in one class showed up in a slightly different way in another class. That spark of connection was very compelling to me. Now perhaps I don’t learn new things quite as quickly, but the connections—the synthesis—comes much easier. So—back to Klemens. I am really enjoying learning from his papers—and I can see clear connections between the studies of thermal conductivity and another problem engaging me these days: which is how isotopes fractionate at a reacting interface. They both involve questions of kinetics—transport processes. They both involve the quasi-momenta of a statistical distribution of traveling particles—in a 3-di lattice for thermal conductivity, across a 1-di interface for reacting isotopes. They both involve an activated process that provides resistance to transport: the scattering of phonons due to lattice anharmonicity for thermal conductivity, and the activation energy barrier for chemical reactions. I love the connections. I love working on a new framework for chemical reactions. I love the dying art of slow science.

I leave with my connection question for discussion in the comments section (please!):
Is diamond simply a 3-di catalyst for heat transport?

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