    
Rastro
Citizen
Username: Rastro
Post Number: 3263
Registered: 5-2004
| | Posted on Wednesday, May 31, 2006 - 10:09 am: | 
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The next time a nuclear particle physicist comments that something is "as big as a barn," you can reasonably consider yourself a little less impressed--and possibly the butt of a geekishly oblique atomic science inside joke. A barn is actually an obscure unit of measurement used to describe the cross-sectional area of atomic nuclei and/or nuclear reactions.
One barn (b) is equal to 10-28 square meters--or roughly the size of a single uranium nucleus. The exact origin of the phrase is unknown, but barn apologists claim scientists used it as "code" in atomic research conversations during the Cold War, while the rest of us know that some whimsical physicist likely named the unit of measurement entirely for its irony.
Science is full of such fanciful units of measurement. Take, for instance, the jiffy, which is a prime example of a nonstandard unit of measurement because its definition changes based on the context.
A jiffy always measures time, but the precise fraction of a second signified by a jiffy varies wildly. In the context of electronics, a jiffy is the time between alternating current power cycles, so the hardware involved literally determines the definition of an electronic jiffy.
This is similar to a computing jiffy, the time between system timer interrupts, which varies by software. For example, in the Linux 2.6 kernel, a jiffy is typically 0.001 second, but in Linux 2.6.13 and later, a jiffy is usually 0.004 second.
And then there are the jiffies, defined experimentally, used by quantum physicists and astrophysicists; usually this unit signifies the length of time it takes for a photon to travel a certain distance within a vacuum. However, whether that distance is a centimeter, a foot, or a nucleon depends on whom you ask.
Want the Trivia Geek's advice? Define your jiffy at the beginning of any academic paper that cites the unit of measurement.
Barns and jiffies aside, we could better describe some of the most humorous (or egregious) ad hoc units of measurement as units of comparison. In data storage circles, a Library of Congress is roughly 20 terabytes of uncompressed textual data. That's the digital equivalent (very roughly) of all the text characters in all the books on the shelves of the U.S. Library of Congress, excluding pictures and ancillary nontextual media.
Such units of measurement help give scale to abstract concepts (such as the capacities of data storage networks). Where things get really silly is when science drags commercial brand names into the picture, especially when it comes to otherwise precise scientific measurements. Such is the case with an obscure measurement for the power ratings of lasers.
WHAT OBSCURE MEASUREMENT OF RELATIVE LASER POWER GETS ITS BASIS FROM A BRAND-NAME HOUSEHOLD PRODUCT? |
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