- #106
homeomorphic
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But they are a good example of "discovered" vs "invented". I could easily understand a person saying the commutative property of multiplication was discovered, as any person looking at a group of chairs assembled in five rows of 10 could easily discover that property themselves. But that doesn't mean multiplication has to be commutative. A person could design a non-commutative version of multiplication - and Hamilton did with his quaternions.
Well, I'm not sure if I agree that Hamilton "invented" that feature of the quaternions. The fact is that 3D rotations don't commute, so that is probably why he realized he needed non-commutative multiplication, I'm guessing. You could say he invented it in order to model the 3D rotations, which are out there in reality. But he discovered that he needed to invent because we aren't born knowing that 3D rotations don't commute, but instead, figure it out ("discover"). In fact, to poke some fun at engineers, I once heard of a mathematician whose whole job was to explain to engineers that 3D rotations don't commute.