Data Management

Geek Trivia: Measures for leisure

What obscure measurement of relative laser power gets its basis from a brand-name household product?

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?

What obscure unit of comparative measurement for relative laser output gets its basis from a brand-name household product?

The unit in question is the Gillette, which references The Gillette Company's synonymous razor blades. In the context of lasers, we can measure output by Gillettes—as in, how many Gillette razor blades can it burn through?

None other than Theodore Maiman, the man who built the first working laser, used this ad-hoc measurement, though no one knows precisely who coined the term. The logic behind it may seem oblique today, but at the time, a Gillette was a handy unit of comparison.

The first lasers could not sustain a continuous beam but instead produced pulsed outputs. If the pulse emission could sear through a relatively uniform, thin strip of metal such as a razor blade, it could give scientists a quick way to gauge the amount of energy released. Depending on whom you ask, Maiman's original pulsed ruby laser had an output of between one and two Gillettes.

Today, the preferred unit for measuring laser power is the watt (which, sad to say, puts lasers in the same context as common household light bulbs). Exactly how many watts equals one Gillette is beyond this Geek's meager technical acumen—but I'll award one chunk of randomly selected TechRepublic swag to the reader who can provide me with the comprehensible mathematic proof that demonstrates a watt-to-Gillette relationship.

(Yes, I passed Physics 101 and Basic Algebra, but it's been a dozen years since I ran a calculus derivative, so keep your entries strictly newb-worthy. Not that I expect anyone to actually meet the challenge, anyway.)

Even if we had a watt/Gillette conversion, it probably wouldn't be that useful. We've come a long way since the earliest days of the laser in the late 1950s and early 1960s.

Today, a common household laser—how cool is it that we can say that?—-like the one in your CD player has a typical output of about five milliwatts (mW), but those of us with a CD burner own a laser capable of a whopping 100 mW—400 of which are necessary to equal the output of one 40-watt light bulb.

Compare that with the National Ignition Facility at the Lawrence Livermore National Laboratory, which is constructing a 192-beam laser array capable of 500 terawatts of power in a single pulse. That's 1,000 times greater than the entire electrical generation capacity of the United States. Smart money says that would equal a staggering number of Gillettes—and some very enlightening Geek Trivia.

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The Quibble of the Week

If you uncover a questionable fact or debatable aspect of this week's Geek Trivia, just post it in the discussion area of the article. Every week, yours truly will choose the best post from the assembled masses and discuss it in the next edition of Geek Trivia.

This week's quibble comes from the April 26 edition of Geek Trivia, "Inspiration for invasion." TechRepublic member Egreer pointed out how—once again—my spell checker has betrayed me.

"I'm pretty sure the [aliens in Space Invaders] were pixelated, not pixilated, as stated in the article—the latter means drunk."

While far be it from me to postulate on the presumed state of inebriation present in fictional hostile extraterrestrials, I'll cop to juxtaposition of homonyms. Thanks for the grammatical vigilance, and keep those quibbles coming.

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The Trivia Geek, also known as Jay Garmon, is a former advertising copywriter and Web developer who's duped TechRepublic into underwriting his affinity for movies, sci-fi, comic books, technology, and all things geekish or subcultural.

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Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

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