The “Best Possible Unit Bar None”

Han_Solo_With_Nano-Second_GunBy The Metric Maven

Bulldog Edition

My friend Kat does her best to make certain I have a contemporary cultural education, but often it does not adhere. Other than the first film, that is actually Episode IV—I had never seen any of the other Star Wars films. She sought to remedy my ignorance and showed me the entire cannon canon. During Episode IV came this infamous statement from Hans Solo:

“You’ve never heard of the Millennium Falcon?… It’s the ship that made the Kessel Run in less than twelve parsecs.”

I noticed this confusion of time and distance when I first saw the movie. I had read Isaac Asimov’s The Universe: From Flat Earth to Quasar, and knew that  a parsec is a single word formed from the two words parallax and second. I also knew what stellar parallax is, and the history of the search to find it. I cringed in the original Star Wars showing. The statement reminded me of 1950s “science fiction” movies filled with hilarious scientific eye-rollers. I love watching those old movies for their campy nature and appearance. Star Wars had Peter Cushing, and so I saw it as more in line of the old Hammer Films. Unlike the 1958 Hammer film Dracula, Star Wars made an impact on culture which is still hard for me to fathom.


Definition of Parsec (Wikimedia Commons)

A parsec is defined using a right triangle that has a side, which is one astronomical unit, and whose opposite angle is one arc-second. The astronomical unit (AU) is a unit that astronomers have created which is roughly the distance from the Sun to the Earth. I say roughly because the distance between the two bodies varies as the Earth orbits the Sun. The parsec is accepted for use with SI and is defined as exactly 149 597 870 700 meters or 149.6 Gigameters. Why not just make it 150 Gigameters? The angle opposite the triangle side of AU length is 4.848 136 8 microradians or one arcsecond. For those who prefer degrees this is 277.778 microdegrees.

When the second leg of the triangle (not the hypotenuse) is computed it has a length of 30.857 Petameters. In summary the Astronomical Unit is 150 Gigameters, and the Parsec is 31 Petameters. Astronomers however don’t use Gigameters and Petameters for distance, they use light years. We have all been told this is the distance that light travels in one year. This distance is 9.4607 Petameters. When we compute the length of a parsec in terms of a light year it is 3.2 light years.

In an earlier essay, I took astronomers to task for not using the large metric prefixes. They encompass the entire observable universe—why not use them? The large metric prefixes even allow for astronomical classifications in terms of metric prefixes, which might be useful for visualization.

I wrote a contributor to an astronomy periodical, and also to their editorial board, inquiring about why there has been no effort to change to metric units. The editorial board did not respond, but the contributor wrote back and said that he was trying to convey:

“….astronomy and sometimes other sciences to the general nontechnical public in a way that makes sense to them. As things now stand in the US, that’s not metric. If we say that rain falls at a speed of 9 meters per second, that’s not as meaningful as 22 miles per hour.

As for planetary distances, I’m not sure if a few hundred million miles can be “felt” by the average person but gigameters would be worse.

As for the light year, it’s the best possible unit bar none. The notion that light, the fastest thing there is, requires 4.3 years to get here from alpha Centauri makes that distance meaningful. Nothing else can do that. Remember, astronomy articles have [a] job to do….and it’s not to force feed an alien seeming system of units, but to help people grasp vast distances. Light years accomplishes that.”

The chicken and egg-little argument is always the first drawn upon. We must become metric as a country to use metric, and no metric will be used popularly until we do, which in turn makes certain the public never sees metric usage, which in turn makes them ignorant and unwilling to change to an “alien seeming system of units.” Doing otherwise, that is using metric, could bring the sky falling down on those who chose to violate this precept. The astronomy periodical would fail, and science “communicators” would all be unemployed.

I see the light year as exploiting a common unconscious substitution, that of time and distance—just like Hans Solo. Often when I ask how far a nearby town might be I hear: “oh….about 45 minutes.” The question was how far, but the answer was time. This time value almost certainly assumes a speed of about 60 miles per hour which is one mile per minute. So the distance is actually 45 car minutes or 2700 car seconds, not just 45 minutes. Traffic jams can radically alter the time, but not the distance.

In my view the light-year is not a unit, it is a culturally accepted mathematical product without a singular definition. A light-year is the speed of light (in a vacuum) multiplied by the length of a year. No units are specified. I could argue that a light year is 1.95 trillion leagues, or 1.117 quintillion barleycorns. What a light year does is allow us to substitute a time metaphor for a defined distance. I heard a person in a recent podcast discuss the idea of intentionally sending out radio signals for aliens to receive. It was pointed out that I Love Lucy broadcasts are about 70 light years out at this point. This could be estimated quickly by assuming that I Love Lucy went on the air about seventy years ago. No distance was computed, it does not tell us how far those VHF electromagnetic waves have traveled, it only is an expression of time as a metaphor for distance.

The light year is the kilowatt hour of astronomy. One could ask their meter reader how much electricity was used, and believe that 20 kilowatt hours is an answer in energy, when it is a time metaphor for energy. I direct you to my essay Joule in the Crown where I argue an actual unit of energy, the joule, should be used to meter electricity and gas rather than kilowatt hours and therms. Therms are a familiar unit?—right?

When we use word descriptions in place of units, we continue to encourage innumeracy. The astronomy contributors insistence on time rather than distance to describe distance is a public disservice in my view, but in his view he is giving the readers “what they want” without ever actually investigating or debating the issue. Hans Solo didn’t make a mistake confusing time and distance, he gave the audience “what they expected—what they wanted” a metaphor in place of a measurement.


A video of my short lecture at Nerd Nite Denver on 2014-09-25 has been posted here.

Metric Wishcraft

Internet-CommentatorBy The Metric Maven

In response to an Op-Ed I wrote promoting the metric system, one commentator stated in opposition to my proposition:

Also saying electricity and gas are measured in improper units then says they should be in gigajoules….kilowatt-hr  and BTUs are amounts of energy just like joules. You can convert BTUs to kWhs and kilowatt hr is metric.  He’s an “engineer” he can convert easily between the two

The internet has provided a place where any immediate thoughtless ejaculation of words can be posted. This concatenation of confabulation was no exception. The specific assertion that caught my attention is his statement that a “kilowatt hr is metric.” Well, I’m afraid I’d have to demur. A kilowatt is metric, and when expressed by this “engineer” in a more fundamental manner is 1000 joules per second. So far, so metric. There is a problem however with multiplying a joule/second by an hour. This will produce joule*hours/second, which is not good dimensional analysis. The base unit for time in the metric system (SI) is the second. An hour is not a metric unit, and multiplying watts by hours immediately disqualifies Kilowatt-hours as a metric expression.

I can only assume that the BTUs were brought up as the units this “commentor” assumed are used for natural gas. My gas bill has the energy of natural gas designated with therms. There is not a BTU to be found. If there were BTUs they would very likely be designated with MMBtu or mmBtu which are one million BTUs. Why the MM or mm?—well Wikipedia—what do you have to say?:

The unit MBtu or mBtu was defined as one thousand BTU, presumably from the Roman numeral system where “M” or “m” stands for one thousand (1,000). This notation is easily confused with the SI mega- (M) prefix, which denotes multiplication by a factor of one million (×106), or with the SI milli- (m) prefix, which denotes division by a factor of one thousand (×10−3). To avoid confusion, many companies and engineers use the notation “MMBtu” or “mmBtu” to represent one million BTU (although, confusingly, MM in Roman numerals would traditionally represent 2,000) and in many contexts this form of notation is deprecated and discouraged in favour of the more modern SI prefixes. Alternatively, the term therm may be used to represent 100,000 (or 105) BTU, and quad for 1015 BTU. Some companies also use BtuE6 in order to reduce confusion between 103 BTU and 106 BTU.[8]

Reduce confusion??? Ok, I think I can summarize that the BTU is a completely ill-defined, readily confusing non-metric unit, which can be expressed in several non-intuitive ways, one of which is therms. There is an interesting metric coincidence that it is often accepted by agreement (in other words we will pretend) that:

  • In natural gas, by convention 1 MMBtu (1 million BTU) = 1.054615 GJ.[9]

This is close to a Gigajoule. How about we simplify life and use Gigajoules in place of MMBtu? I have shown how simply a utility bill can be expressed with Gigajoules. I realize that the “commenter” is probably so well-off that he need not be bothered with quantifying energy usage, but this “engineer” does, and sees no reason for allowing confusopolies to continue to obscure billing information.

One can also note that his use of a simile: “BTUs are amounts of energy just like joules.”  is not exactly apt. Wikipedia also has this to say:

A BTU is the amount of heat required to raise the temperature of 1 avoirdupois pound of liquid water by 1 degree Fahrenheit at a constant pressure of one atmosphere.[2][3] As with the calorie, several definitions of the BTU exist, because the temperature response of water to heat energy is non-linear. This means that the change in temperature of a water mass caused by adding a certain amount of heat to it will be a function of the water’s initial temperature. Definitions of the BTU based on different water temperatures can therefore vary by up to 0.5%

The BTU is not a well-defined unit for energy, and neither is the calorie, that’s why the joule is used for energy by Engineers, scientists, and persons who want accurate energy bills, and those that have left the 19th century behind.

The “discussions” that occur in comment sections of—well—any blog or posting, have those who assert with great confidence, “information” that sounds right to those who are ill-informed, in an attempt to convince both those reading the assertion and the person making it, to remain so. The length of this blog is testament to this. Note how many words it took to deal with the flawed assertion of but one person. (With apologies to Mark Twain): The most outrageous ignorance that can be propagated will find believers if a man only tells them with all his might. This is what metric proponents encounter constantly.


Great-American-DisasterCNN posted a piece in their “Great American Stories” series entitled Refusing to Give an Inch. The entire story is essentially a celebration of U.S. failure. How is that a Great American Story? The majority of the piece was cribbed from John Bemelmans Marciano’s anti-metric polemic Whatever Happened To the Metric System. A review of this monograph may be found here.

I was contacted by one of the authors by email last February. The story was to be about the controversy over the metric road signs in Arizona.  I sent the reporter links to A Tale of Two Iowans, The Chain Gang, and my response to NIST’s rejection of a We The People Petition to change the U.S. to the metric system. I told the author I was willing to talk at length, at anytime, and that they could find much useful information contained in my blogs.

The video that accompanies the written story is surprising in that a number of people interviewed didn’t seem bothered by the metric road signs. They even seemed to have a fondness for them. One person who recently moved there, soon didn’t notice the difference and seemed fine with the signs. This supports my thesis about The Metric Populist Revolt That Didn’t Happen. Much like the California DOT, that went from metric back to Ye Olde English, the Arizona spokesman speculated about dual-unit signs. He saw that as “the best of all worlds for everyone.” This is simply a way to first give U.S. citizens a way of ignoring the metric designations, and then eventually purging them. See Naughtin’s First Law.

The reason for the replacement of the metric road signs, which look perfectly fine, is they don’t have as much refection at night as desired. I suspect that all of the signs in Arizona must have been changed because of this new specification. Strangely there was no public outcry about the “massive costs” involved with replacing all the Ye Olde English signs. That would have been a perfect time to make all the road signs in Arizona metric. Metric resistance is not about cost, it has no rational basis.

I had hoped for a story with something other than an extended interview with Marciano that contains statements like:

Marciano, however, makes a credible argument for the old way of counting, which is based on everyday things and parts of the body.

“People say the metric system makes sense,” Marciano says, “But in nature we don’t think about dividing things by 10, do we? We think of halves and feet and thirds.”

Acres, for instance, were based on the amount of land a man could plow in a day.

“Throughout history we have measured things by ourselves,” Marciano says. “We are really losing something with metric.”

And another thing: People think the metric system has something to do with science.
It doesn’t, Marciano says, except that it is used in science and every scientist will
probably put forth a convincing argument for why it’s silly not to be metric.

The metric system is very “body friendly.” a long pace is almost exactly a meter (1000 mm). I’ve done this and checked buildings with a laser. The dimensions are remarkably close. The distance between a person’s nose and the tips of their fingers is about a meter. The width of a male hand, Marciano’s hobby horse measurement poster unit, is generally 100 mm. So is the length of many index fingers. The width of a pinky fingernail is about 10 mm.

I have dedicated my life to engineering  and science. Marciano’s statement that the metric system has nothing to do with science is simply at odds with the last two centuries of history. It is like stating that biology has nothing to do with lifeforms. I direct my readers to my essay The Americans Who Defined the Meter. The fact that the Earth is about 40 Megameters (40 000 Km) in circumference, is no simple coincidence. Englishman John Wilkins was tasked by the Royal Society of London to develop a universal measurement system that all scientists could use. When France finally implemented the metric system, it was guided by a number of very famous scientists. It’s science all the way down. The metric system has also been refined to make everyday measurement much easier for everyday people than Ye Olde English. The details are in my blogs.

CNN further informs us that:

…. John Bemelmans Marciano gave up writing the popular “Madeline” children’s books started by his grandfather and last year published “Whatever Happened To The Metric System?”

Marciano says his young editor had no idea the United States had come within millimeters of metrication. The book reveals a fascinating history of how this nation ended up keeping a system in which 16 ounces make a pound, 12 inches make a foot and 3 feet make a yard.

Marciano knows that we never came within a barleycorn of becoming metric. I’ve detailed this, here, and here and it’s tiresome to have metric revisionist history constantly propagated by Marciano and the lazy media. Marciano’s book does not explain what happened to metric system, the book has almost no metric content, and is only a long juvenile paean of schadenfreude directed at the U.S. metric failure. If you want to know why the U.S. is not metric, you will not find the answer in Marciano’s book, you will find it in Hector Vera’s PhD thesis: The Social Life of Measures Metrication in the United States and Mexico, 1798-2004 (September 2011). Worst of all for me was this (forgive me for re-quoting):

There are blogs like “Metric Maven” and even a book on the subject. John Bemelmans Marciano gave up writing the popular “Madeline” children’s books started by his grandfather and last year published “Whatever Happened To The Metric System?”

This, in my view, makes it look like my blog and Marciano’s anti-metric polemic are somehow complimentary or equivalent when they are completely at odds. I guess that it was good that at least I have a link. It would have been nice if this had been an article that does not celebrate a disaster as an American triumph, but I guess no matter what happened, in CNN’s view the lack of the metric system is a “Great American Story.”