Keep Eye on That Blue Sky
By Bill Sones and Rich Sones Ph.D.
Question: Go outside on a clear day and peer with one eye through a long cardboard tube (as for paper toweling) at the lovely blue sky, keeping the other eye open. Guess what’s going to happen to the color.
Answer: Within a few seconds the small disk in the tube will start to lose its blueness, becoming whiter and whiter, while the other eye continues to see the original color, says Peter Pesic in “Sky in a Bottle.” One 19th-century observer regarded this bleaching as proof the sky’s blue is an optical illusion. But the same “bleaching” of your retinal receptors will occur when you stare at any uniform blue field of view, such as a bright blue cloth.
Likely this is a cortical phenomenon relating to the lack of information, e.g., contours and texture, in the signal, says University of Southern California psychologist Ernest Greene. “Habituation” occurs as the brain in a sense “turns off” to the lackluster visual event.
Question: Why is vitamin C called vitamin C, and what is a vitamin anyway? Whatever happened to vitamins F and G?
Answer: The C indicates it was the third vitamin ever identified, say Penny Le Couteur and Jay Burreson in “Napoleon’s Buttons: 17 Molecules That Changed History.”
The naming system has some flaws though: The word “vitamin” comes from a contraction of “vital” and “amine,” meaning a nitrogen- containing organic compound, because it was originally thought all vitamins contained at least one nitrogen atom. But only the B vitamins actually do. The original B vitamin was later discovered to consist of more than one compound, hence vitamin B1, B2 etc (but no 4, 8, 10, 11). Also, several supposedly different vitamins were found to be the same compound, and thus the terms vitamin F and vitamin G have fallen out of use.
Now for a pet curiosity: Why don’t your dog and cat need as much dietary vitamin C as you do? Actually, they need none at all, says Le Couteur. In both — and most other mammals — ascorbic acid is made in the liver from the simple sugar glucose. Humans are one of the exceptions and would do well to get their “RDA” of C.
Question: Why is ice so slippery? Better watch your step on this one. . . . (a) pressure melting puts water underfoot (b) frictional heating under skis or skates creates the glide (c) it’s just ice’s icy nature
Answer: (a) and (b) used to be given, but it’s now known that the pressure under a walker’s boots or the friction of skate blades against ice doesn’t play much of a role in melting, reports “Physics Today.” As early as the 1850s Michael Faraday tested ice cubes that were sticking together and concluded that ice surfaces must just inherently consist of a thin film of water, at whatever temperature. So mark (c).
Even ice at -200 F has a “quasi-fluid layer” that makes the stuff slippery, says Exploratorium.edu. This may help explain the “fast ice” and “slow ice” of hockey: As the ice gets warmed, the number of slippery layers increases, until skaters need to “slosh” through so many layers that the friction slows them down. On the other hand, these extra layers can help “soften” the landing of a figure skater, whose ice should be warmer than for hockey players.
By the time ice gets down to -250 F (-157 C), the slippery layer is just a single molecule thick! Nanohockey, anyone?
Send STRANGE questions to brothers Bill and Rich at strangetrue@compuserve.com, coauthors of “Can a Guy Get Pregnant? Scientific Answers to Everyday (and Not-So-Everyday) Questions,” from Pi Press.