User blog comment:Ricizubi/The main villains from the Grand Line/@comment-3202520-20120122143947/@comment-3119203-20120123135526

Ok, so if light was traveling through a dense medium then it would be slower than electromagnetic waves traveling through a vacuum. Makes sense to me, but if we compare the two side-by-side, then light would win if they were in the same material. Good point though.