> For more than a decade, chemical engineer Jiro Abe and colleagues at Aoyama Gakuin University in Japan have been studying the light-sensitive properties of photochromic materials, particularly those derived from a compound called hexaarylbiimidazole (HABI). In its natural state, HABI is colorless, but when ultraviolet light breaks one of the bonds in the molecule, it produces a version that is dark blue. The problem has been that the transformation takes tens of seconds or longer, so the only commercial application has been sunglasses that slowly darken. When Abe's team began analyzing HABI's chemical structure through simulations and laboratory experiments,...