STRANGE BUT TRUE
Q: Before 1954, when Major League Baseball instituted rule number 3.10, the game could be decidedly unpredictable, if not unsafe. What exactly is rule 3.10?
A: Picture the scene on the field: The inning ends and the baseball players run off, leaving behind their gloves where they stood, in the outfield, the infield, into foul territory, says Dan Lewis on his “Now I Know” website. Opposing teams would often steal or hide each other’s gloves, “causing panicked fielders and delayed games.” If word got around that a player had an aversion to certain creatures, that player “immediately became a target:” New York Yankees shortstop Phil Rizzuto, for one, found all kinds of dead things in his glove — mice, rats, frogs, lizards (Sports Illustrated).
What ultimately brought about a change was how unsafe it had become to have a foreign object on the field, with the likelihood that an idly lying glove could alter the outcome of a game due to an injury or error.
Rule No. 3.10 states: “Members of the offensive team shall carry all gloves and other equipment off the field and to the dugout while their team is at bat. No equipment shall be left lying on the field, either in fair or foul territory.”
Q: While reviewing maps of lightning activity, atmospheric scientist Joel Thornton and his colleagues noticed a couple of narrow straight lines over the east Indian Ocean and South China Sea. Lightning happened nearly twice as frequently along these lines compared with the surrounding regions. Eventually they figured out what was going on. Can you?
A: The lines turned out to correspond to two of the busiest shipping lanes in the world. Comparing lightning maps to engine exhaust “soot” maps, a clear correlation emerged (“Geophysical Research Letters”). “These [soot] particles act as the nuclei on which cloud drops form and can change the vertical development of storms, allowing more cloud water to be transported to high altitudes, where electrification of the storm occurs to produce lightning. These shipping lanes are thus an ongoing experiment on how human activities that lead to airborne particulate matter pollution can perturb storm intensity and lightning.”
Q: Accidentally mistype your credit card number into a website and you’re likely to get an immediate notification of the error, before any communication with your bank. Why? Are you ready for this one?
A: Not all 16-digit numbers are valid candidates for credit card numbers. According to Richard Webb in New Scientist magazine, there is a simple arithmetic procedure that checks validity, patented in 1954 by Hans Peter Luhn of IBM. Suppose you type in 0123456789012345 as your credit card number. The Luhn algorithm goes like this:
First, reverse the sequence of the digits, giving 5432109876543210.
Second, add up the first, third, and fifth digits, and so on, to get 5+3+1+9+7+5+3+1 = 34.
Third, double each of the second, fourth, and sixth digits, and so on, giving 8, 4, 0, 16, 12, 8, 4, 0. If any of these numbers have two digits (like 16 and 12), replace them with the one-digit number obtained by adding the two digits together (16 becomes 7, 12 becomes 3). Then add up all eight numbers to get 8+4+0+7+3+8+4+0 = 34.
Fourth, add together the results of steps two and three, giving 34+34 = 68. Only if this number ends in 0 is the entered credit card number a valid candidate. Since 8 is not 0, the entered number 0123456789012345 is not valid.
The Luhn test is a quick and convenient way of screening out most typos: it will flag any singledigit error and almost all transpositions of two adjacent digits.