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The big deal about silicon (and other semiconductors) is that they have allowed and disallowed bands of energy that can carry current. By controllably injecting electrons into those bands, you can control whether something acts like a metal or insulator, and hence digital logic.
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The mechanical properties of sand piles are generally mysterious. The pile is supported by long "force chains" with fractal structure. And if you make a histogram of the force F on each sand grain, there is a mysterious power-law vanishing of the probability when F gets small.
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I was intrigued about whether there was any solid-state physics angle to why iron ended up disrupting bronze on the civilizational stage besides just better availability and the fragility of the global bronze age tin trade
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There's probably a shorter version of this that's a very good challenge for anybody. I could probably get to 10 interesting materials about which I could point out something weird/novel but then I'd run out of steam
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