Sunday, March 04, 2012

As Infinitesimal as a Barn

I’d guess that most who read this blog don’t often encounter barns, unless maybe it’s Dress Barn, in which case you deserve better than that because no one deserves Dress Barn. Furthermore, who thought that anyone would want to buy clothes from a barn? Are humans so removed agricultural life that they don’t realize that cows and other unflatteringly large stock animals live in barns? Is Dress Barn, like, the lady version of a big-and-tall shop? Is the decor barn-themed? Is there hay on the floor? Do salesgirls pass out salt licks and cud?

I’m stopping. This is not a post about Dress Barn, but it is about the word barn in an unusual context — a context that just happens to be my word of the week.
barn (bärn) — noun: 1. a large farm building used for storing farm products and sheltering livestock. 2. a large shed for the housing of vehicles, such as railroad cars. 3. a unit of area equal to 10-24 square centimeters, used to measure cross sections in nuclear physics.
Guess which of these American Heritage Dictionary definitions I think is the most interesting?

Yes, barn has a scientific use: describing an extremely small amount of surface area. In fact, 10-24 square centimeters is roughly the area of the cross section of a uranium nucleus. How did this scientific barn come to be, and why is it grouped with the “farmhouse” definitions as opposed to being listed as a separate barn, since it couldn’t possibly share an etymology with regular definition of the word?

The terms are, in fact, related, and in a lighthearted way I wouldn’t associate with men who split atoms. According to the physics journal Symmetry, the name arose in 1942, when Purdue University physicists Marshall Halloway and Charles Baker took a moment away from the Manhattan Project to eat dinner and bat around potential names for the cross section measuring 10-24 square centimeters. On the subatomic level, this expanse is actually quite large, or “as big as a barn,” so barn and whimsy won out as the term and the mood, respectively. The name stuck, and today this common word barn — which, by the way, comes from a the Old English bereærn, literally “barley house” — gets paired with all the metric system prefixes denoting various sizes, from megabarn (10-18 square centimeters) down to the far more interesting micromeasurements of attobarn (10-46 square centimeters), zeptobarn (10-49 square centimeters) and yoctobarn (10-52 square centimeters). But here’s the especially quaint footnote to all this atypically folksy barn business: Though rarely used, a special term exists for the yoctobarn measurement. It’s shed, and no, I’m not kidding. And in case you’re ever describing an area of 10-34 square centimeters and you don’t feel like using the standard terminology, microbarn, you can always go with the synonym outhouse. No, really.

vintage barn (weiser, idaho), via
Yay, barns!

Previous words of the week after the jump.

6 comments:

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    1. I'm sorry, I don't follow.

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  2. "in a lighthearted way I wouldn’t associate with men who split atoms"

    Man, they named one of the fundamental building blocks of the world after the nonsense phrase, "Three quarks for Muster Mark!" These dudes are pretty frigging light-hearted.

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    1. That's actually a good point. I misjudged. Maybe you have to keep a sense of humor in order to keep from losing it when contemplating the essence of the universe.

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  3. Apparently a couple of other guys working on the Manhattan project named the Monte Carlo method of algorithmic computations after the Monte Carlo Casino, where one of the guy's uncles threw all of his money away (via Wikipedia, of course).

    Scientists are hilarious.

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    1. Scientists are hilarious, I will grant you that. But I maintain that the religious types who reject science are funnier, if for different reasons.

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