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January 11, 2009


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Continuing to educate myself by reading older posts I haven't seen, I came to this one, which rings a couple of bells. As the linked article says, the optical phenomenon involved is birefringence, seen in Iceland spar and other calcite crystals, and discovered as an effect of compression by David Brewster, famous among other things for inventing the kaleidoscope. Photoelasticity was brilliantly employed, to make architectural history empirical, by Robert Mark, author of "Experiments in Gothic Structure." Mark stressed thin sectional plastic models with winds and loads to visualize and measure the forces that kept Gothic cathedrals standing, or sometimes didn't. Applying the technique to many-body dynamic systems is a great idea. How long until someone proposes birefringence as a cause of earthquake lights, I wonder?

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