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(Now thinking about having a day in Calculus class where you force students to punch a block of cornstarch water, and then say: "You see! This is what happens when you rely too heavily on the first-order Taylor expansion!!")
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38. QUASICRYSTALS are materials for which the symmetry is inconsistent with a periodic tiling. For example, a five-fold symmetric crystal is not supposed to exist, since it's impossible to tile space with pentagons. Nonetheless, such materials can exist!
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39. Most materials expand in one direction when you compress them in a perpendicular direction. But AUXETICS are materials that either shrink or expand in both directions simultaneously. (In engineering terms, they have a negative "Poisson ratio")
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40. OPTICAL METAMATERIALS are human-made materials in which a bunch of small electromagnetic resonators are arranged so that their interactions produce unusual behaviors of light (or EM waves in some band of frequency). For example, you can engineer negative index of refraction!
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41. There is a lot of excitement and mystery right now about SAMARIUM HEXABORIDE, which looks simultaneously like an insulator and a quantum metal, in ways that we are still grappling with. See this earlier thread: (twitter.com/gravity_levity)
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30/30 Since this is a paper whose major point is mostly to rain on a fun quantum hype parade, I expect it to be essentially ignored.
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I think that I am out of time and energy now, and tired of spamming your timelines. So let's draw this thread to an END. Thank you all for coming along with me. It's been fun, and nothing at all like a systematic list of "the 100 most interesting materials".
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