> I found a photo in Roger Penrose's _ Emperor's New Mind_, page 564 in > our library copy. It is early, and different from the later > representations. If you surf for "penrose aluminum-manganese alloy" > (sans quotes), you should come up with some good information. > > I struggle to follow Penrose, but that's my shortcoming. He's a very > good instructor and writer.
I never made it through the third chapter of that book; it always ended up being thrown against the wall. Some day I'll try to read it again.