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.
Conversation
21. SAND PILES
Here's something interesting about a pile of sand:
Every material has its own characteristic "angle of respose", which is the angle it makes with the ground when you pile it up.
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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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22. STEEL is just iron + carbon melted together, but it turns out that there is a whole zoology of very different things you can get from this process.
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I don't know if I can say anything that sounds different from what I said about steel.
Alloys are hard.
copper.org/resources/prop
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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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I'm sure there is, but I'm sorry, you should have assigned the topic to a materials scientist
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actually, as I make this list I keep thinking how very different it would be if it was made by a chemist, or a materials engineer, etc.
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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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