## Posts tagged ‘metric’

### Our Weigh or the Highway

On the outskirts of Paris, in a triple-sealed chamber, sits a golf-ball sized cylinder made of platinum and iridium. It’s officially known as the International Prototype of the Kilogram — or IPK, for short — but locals refer to it as *Le Grand K*.

Cast in 1879, the IPK serves as the international standard for mass. For a century-and-a-half, the accuracy of any weight measurement was linked to this very precisely hewn hunk of metal.

The kilogram is the only unit still defined in terms of a manufactured object, and that’s shaky and solitary ground on which to rest. In 1960, the only other SI unit still based on a physical artifact — the meter — was redefined in terms of the wavelength of light from a specified source, linking it to natural phenomena.

But no longer.

Today, Le Grand K will be retired when representatives from 60 countries will meet in Versailles to approve a new definition of the kilogram. Officially, the change won’t take place until May 20, 2019, which means that for a short time, the IPK, Pete Sessions, and Claire McCaskill will occupy a similar state of lame-duck limbo.

And what is the new definition for the kilogram? It’s pretty straightforward…

The kilogram (kg) will be defined by taking the fixed value of the Planck constant

hto be 6.626 070 15 × 10^{−34}J⋅s. The unit J⋅s is joule-seconds, which is equal to kg⋅m^{2}⋅s^{−1}, where the meter and second are defined in terms ofc, the speed of light, which is 299,792,458 meters per second (m⋅s^{−1}), and Δν_{Cs}, the ground state hyperfine splitting frequency of cesium-133, which is 9,192,631,770 Hz.

See? Easy peezy.

Over time, the IPK has, surprisingly, lost weight. And scientists can’t really explain why. The cylinder now weighs about 50 micrograms, or roughly the weight of an eyelash, less than it weighed in 1879. The irony, though, is that a kilogram, by definition, is equal to the weight of the IPK. So, technically, it isn’t that the kilogram has lost weight; in truth, the rest of the world has been getting a little heavier. (Keep this factoid in your back pocket for a few days. It is perhaps the best and most scientific excuse you’ll be able to offer if you don’t like the reading on your scale around the holidays.)

All this talk of Le Système International makes me think about the many important benchmark conversions that should be part of every science curriculum:

2000 mockingbirds = 2 kilomockingbirds

10^{12} microphones = 1 megaphone

10 cards = 1 decacards

1,000 grams of wet socks = 1 literhosen

And the most important benchmark, for when you need to convert between expatriate poets and televangelists:

And finally, if you’ve read this far, a PG-13 passage from *Wild Thing* by Josh Bazell:

In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade — which is one percent of the difference between its freezing point and its boiling point. An amount of hydrogen weighing the same amount has exactly one mole of atoms in it. Whereas in the American system, the answer to “How much energy does it take to boil a room-temperature gallon of water?” is “Go fuck yourself,” because you can’t directly relate any of those quantities.

### XXXIII for Increased SEO

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Beware the Ides of October! Check back on October 15 for a MJ4MF World Premiere! |

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Today is 10/10/13, or X/X/XIII in Roman numerals. Three years ago, I published XXX Rated to celebrate 10/10/10, and it has consistently been one of my most visited pages. Not surprising. Today’s top searches which led to my blog were:

- xxx sex
- sex xxx
- metric system jokes
- xxx.sex

Well, at least *someone* was looking for math jokes when they found my blog!

In honor of National Metric Day* and to appease most people who stumble across this blog, here’s a joke that mixes metric and sex. It’s subtle; pay attention.

The metric conversion for 69 is 181.

And another?

What do sex and metric conversions have in common?

I enjoy doing both, but most of the time I do them alone in my room.

And a sorta, kinda Roman math joke…

A Roman soldier walks into a bar. “Martinus, please.”

The bartender replies, “You mean

martini?”The soldier says, “If I wanted more than one, I would have asked for it!”

And finally…

When is 6 equal to 8.5?

In Roman numerals, the number SIX can be translated to 8.5. Remember that IV = 4, because a smaller number (I = 1) precedes a larger number (V = 5). With SIX, S = ½, I = 1, and X = 10. Since both S and I precede X, they should be subtracted: 10 – ½ – 1 = 8.5. Hence, 6 = 8.5. Q.E.D.

* Not an official holiday. See Pat Naughtin’s declaration as well as the U.S. Metric Association Metric Week.

### Conversion Perversion

“Be there in a jiffy.”

If someone says that to you, then you know that that person should arrive soon. But did you know that *jiffy* is a technical term? Similarly, the expression “two shakes of a lamb’s tail” used to indicate a short period of time, but the unit of time known as a *shake* now has a specific designation.

- 1 sec = 100 jiffies = 100,000,000 shakes

I’m big into conversions. I often tell folks, if you need to convert between televangelists and expatriate poets, the following picture may be helpful to you:

That is, 1 Ezra Pound ≈ 454 Billy Grahams.

The following are some other fun conversions.

- π sec ≈ 1 nanocentury

It’s interesting that this is so accurate. It is within 0.5%.

- 1 furlong per fortnight (FPF) ≈ 1 cm/min

This one is even better. The error is less than 0.000025%.

- 1 m/s = 1 Hz/dpt (Hertz/dioptre)

This is what can happen when common units are replaced with uncommon units. *Hertz per dioptre* is an inside joke among physicists and yet another reason not to hang out with them. (*Dioptre* is a unit of measure for the optical power of a lens.)

- 1 square = 100 square feet

The term *square* is used in the construction industry, typically to measure a roof. For example, if a roof has an area of 1,000 square feet, then the contractor would order 10 squares of shingles. But you wouldn’t want to use this unit in regular conversation, because it leads to awkward phrases like a “one-square square,” which would be a square that measures 10 feet on a side.

- 1 gal ≈ 3 + π/4 L

This is one of my favorite conversions. It’s accurate to 0.00000003%.

- 1 Hubble-barn ≈ 13.1 L

A *Hubble length* is the length of the observable universe (a very, very big length), and a *barn* is 100 square femtometers (a very, very small area), so it’s neat that their product gives a very tangible volumetric result.

- 1 stone = 14 pounds

When asked for my weight, I usually respond, “About 13 stones.” Such a reply leaves room for interpretation, and it could be assumed that I weigh as little as 175 pounds or as much as 189 pounds. And I’m fine with that. What kind of rude bugger asks your weight, anyway?

On a related note, the following formula can be used to approximate the U.S. population for a given year. Let *x* = the last two digits of the year, and let *y* = the projected U.S. population for that year (in millions). Then,

*y*= π*x*+ 276

This result is based on projections from the Pew Research Center. This formula provides an accurate estimate (within 1%) of the actual population for every year since 2000, and it should give a reasonable projection for the next several decades, assuming there are no major catastrophes.

### Why Metric is 10 Times Better

Asking why the U.S. has not switched to the metric system is almost as pointless as asking why we still observe Daylight Savings Time.

Some folks still have trouble converting between the two systems, but there are celebrity mnemonics that can be used to help remember typical conversions. For instance, 1 Ezra Pound ≈ 454 Billy Grahams.

Here’s a trivia question for you: Besides the U.S., what other countries have not officially adopted the metric system? Are you ready for the answer? According to the U.S. Metric Association, Liberia and Myanmar are the only two additional hold‑outs of significance.

Truth be known, the U.S. has gone metric. The yard, the pound, and the gallon are now officially defined by reference to metric units. In 1975, the federal government adopted metric as the nation’s “preferred measurement system.” Though the United States Metric Board was created to manage the transition, the only noticeable change by the early 1980s was that liquor and wine were labeled in liters.

But seriously, there are plenty of great reasons why we haven’t switch to *Systeme Internationale*:

- Referring to football as a “game of millimeters” just doesn’t have the same ring to it.
- Inchworms will become centipedes.
- Meter sticks are very stubborn — they won’t give an inch!
- Currently, an ounce of prevention is worth a pound of cure. The conversion to metric would mean that a gram of prevention is worth approximately one‑sixtieth a kilogram of cure. Yuck.
- Nobody wants to go traipsing all over Hell’s half‑hectare.
- Cemetery workers would strike if they were asked to bury the dead “six meters under.”
- You could no longer love someone a bushel and peck. You would have to love them 37.9 liters.
- The famous barroom reprimand, “Mind your p’s and q’s” (pints and quarts), would become, “Mind your h’s and l’s” (half‑liters and liters).

Seriously, folks, it’s high time we made the transition. People opposed to metrication are just being *de‑feet‑ist*.

### More Math One-Liners

As we were dressing to play in the snow, I asked my son Eli if I could wear his hat. His response was an emphatic, “No!” When I asked why, his one-liner response made me chuckle:

Because your chin is too far from your head.

Here are some other one-liners that I’ve always enjoyed.

Pure mathematicians are like lighthouses in the middle of a swamp — brilliant, but completely useless.

If God wanted us to use the metric system, why did Jesus have 12 apostles?

I’m not worried about losing my job to a computer. They’ve yet to invent a machine that does absolutely nothing.

For every complex mathematical problem, there is a simple and elegant solution that is completely wrong.

For every complex mathematical problem, there is a solution. The difficulty lies in finding it.

A mathematics lecture is a process for transferring the notes of the teacher to the notes of the student without passing through the minds of either.

In a graph, the thickness of the curve is inversely proportional to the reliability of the data.

Statistics are like a bikini — what they reveal is suggestive, but what they conceal is vital.