PEDANTIC: GeekPress quotes this Mercury News article which says: "IBM researchers have created the world's smallest solid-state flashlight -- a tube 50,000 times thinner than a human hair. It emits a glow that is invisible to our eyes, but ideal for devices that use light to send data in fiber-optic cables and the like." Nifty! Except, what does "50,000 times thinner than a human hair" mean?
Now, if something is 50,000 times thicker than a human hair then that's pretty clear, because "thickness" is a property that all physical objects possess and which can extend, in theory, to infinity. How thick is your car? How thick are you? Easy to answer. If a human hair has a thickness of 1 Human Hair Unit, then something 50,000 times as thick has a thickness of 50,000 HHUs. "Thinness" however, is a property which can only go down to zero, and which implies that a comparison has already been made to some "standard" thickness. The author is mixing denotation. If you're fat and your friend's waistline is half of yours, is he half as thick as you or twice as thin? Well, you're not really thin at all: you're negative thin, since you're fat. Likewise, I'm not a thousand times thinner than a skyscraper -- that just doesn't make any sense. "50,000 times" implies that the flashlight is much more something than a human hair, but "50,000 times thinner" attempts to say that it's "50,000 times more less thick" -- strange and twisted.
Although I'm sure everyone knows what the writer means when she says "50,000 times thinner than a human hair", it would annoy me less if she had written "1/50,000th as thick as a human hair".