Every time an astronaut gets off the ground, he or she owes a debt to the Wright brothers, not just because the boys dared to fly, but because they were smart enough to use a newfangled aluminum alloy to lighten the load of their engine and make flight possible. The art and science of creating new, lighter and stronger metal alloys has progressed remarkably in the intervening 100 years. But many scientists now envision a looming limit to this progress owing to a mature science that will now make only incremental gains. Then along comes Takashi Saito, a Japanese researcher...