Well, it's true that the article says "seven-millionths". I would guess it's a lot more likely that this is an editing failure, introducing a hyphen where no h

Well, it's true that the article says "seven-millionths". I would guess it's a lot more likely that this is an editing failure, introducing a hyphen where no hyphen should be, than that they meant to divide a second into seven million equal parts. For one thing, as SECProto alludes to, English would normally require you to say "less than a seven-millionth of a second" if that was what you meant. There's no such thing as saying "less than weeks". You have to specify less than how many weeks. less than (seven) (millionths of a second) ordinary grammar, ordinary unit choice less than (seven millionths of a second) improper grammar, bizarre unit choice.