Yes! The New Science of Strong Materialsis a marvelous book, highly recommended. It explains simply and in detail why most materials are at least an order of magnitude weaker than you’d expect if you calculated their strength theoretically from bond strengths: it’s all about how cracks or dislocations propagate.
However, Eliezer is talking about nano-tech. Using nanotech, by adding the right microstructure at the right scale, you can make a composite material that actually approaches the theoretical strength (as evolution did for spider silk), and at that point, bond strength does become the limiting factor.
On why this matters, physical strength is pretty important for things like combat, or challenging pieces of engineering like flight or reaching orbit. Nano-engineered carbon-carbon composites with a good fraction of the naively-calculated strength of (and a lot more toughness than) diamond would be very impressive in military or aerospace application. You’d have to ask Eliezer, but I suspect the point he’s trying to make is that if a human soldier was fighting a nano-tech-engineered AI infantry bot made out of these sorts of materials, the bot would win easily.
Yes! The New Science of Strong Materials is a marvelous book, highly recommended. It explains simply and in detail why most materials are at least an order of magnitude weaker than you’d expect if you calculated their strength theoretically from bond strengths: it’s all about how cracks or dislocations propagate.
However, Eliezer is talking about nano-tech. Using nanotech, by adding the right microstructure at the right scale, you can make a composite material that actually approaches the theoretical strength (as evolution did for spider silk), and at that point, bond strength does become the limiting factor.
On why this matters, physical strength is pretty important for things like combat, or challenging pieces of engineering like flight or reaching orbit. Nano-engineered carbon-carbon composites with a good fraction of the naively-calculated strength of (and a lot more toughness than) diamond would be very impressive in military or aerospace application. You’d have to ask Eliezer, but I suspect the point he’s trying to make is that if a human soldier was fighting a nano-tech-engineered AI infantry bot made out of these sorts of materials, the bot would win easily.