Wishing Upon a Star


Alpha Centauri (Wikimedia Commons)

By The Metric Maven

Bulldog Edition

A wish can be a supernatural request which is granted by a supernatural talisman. The song, When You Wish Upon a Star, when modulated onto an electromagnetic (radio/light) wave, that is traveling in a vacuum, moves at 300 Megameters per second. This is only true if the light is traveling in a vacuum (we’ll get back to that), and space is a pretty good vacuum. Einstein was rather clear about the fact that information cannot be propagated faster than the speed of light. This means that any receiving star (other than the Sun) would have to wait years to know that a wish was requested of it.

The Alpha Centauri star system is the closest and it would take light a little over four years for a supernatural request to arrive, so your wish would be delayed by at least that amount of time. Alpha Centauri is also only seen in the U.S. for very short periods of time, and only at latitudes which are south of Houston Texas and is practically invisible. Assuming Alpha Centauri is the ineffective talisman that I expect it is, one would have to wait about eight-years for a non-reply. If you wish on a star that takes light over 75 years or so to arrive, well, then you will not be alive to receive the non-reply. Unless you plan to live to 150 years of age. The odds of that happening are not good.

Astronomers like to conflate time and distance into a strange and exotic sounding description called a light-year. Each of the multitude of stars we view at night has light that emanated at a different time, and so when a star is farther and farther away in distance, we witness how it looked longer and longer ago. Every star has a unique time delay associated with it. The further we look out into the Universe, the farther back in time we see.

When you look at any object or person, you do not see them instantaneously. If a person is 500 mm from you, the light you see has taken about 1.67 nanoseconds to impact your retina. The person is therefore 1.67 light-nanoseconds away from you. If you see an erupting volcano that is 1000 meters distant, the image seen by your eyes has a “distance” of 3.33 light-microseconds. Standing in Denver Colorado, Pike’s Peak (which is visible from Denver), is about 160 Km distant or 533 light-microseconds. Which has more meaning in terms of distance?—160 Kilometers or 533 light-microseconds? This is not really fair one might argue. As far as a person is concerned, this amount of time is instantaneous, and so it makes perfect sense to use distance and forget about the propagation speed of light.

When does a product of the speed of light and time begin to be a distance that makes some sense? There are a lot of choices:

Light-Second 300 Mm (Megameters)

Light-minute 18 Gm (Gigameters)

Light-hour 1.08 Tm (Terameters)

Light-day 25.92 Tm (Terameters)

Light-week 181.44 Tm (Terameters)

Light-month 725.76 Tm (Terameters)

Light-year 9.46 Pm (Petameters)

Light-Century 946 Pm (Petameters)

When the New Horizons probe was near Pluto, it took about four hours for the radio signal to propagate from the Earth to the spacecraft. It was not typically said that the probe was 4 light-hours from the Earth. Why not use light-hours if the conflation of light-speed and distance is so useful? A light second is a 3000 hour long (100 Km/hr) drive, or 3000 car-hours. It is also 7.5 times around the Earth. A light-minute is not enough distance to traverse from one planet to the next in our solar system. The light hour is  a distance from the  Sun to a point between Jupiter and Saturn. The light-day, light week and light month are all well short of our nearest star system, Alpha Centauri. A light century (which no one generally uses) is 100 light years. Betelgeuse is over six times this far, and it can be called a nearby star. The length across the Milky Way galaxy is about 100 000 to 180 000 light-years. Our closest galaxy is Andromeda and it is 2 500 000 light-years distant. The observable universe is about 91 000 000 000 light-years. It is hard to see that this single “unit,” the light-year, is really descriptive over the large dynamic range of the Universe. Enormous numbers cannot be visualized, but they can be categorized, which gives them more intrinsic relative meaning. The metric system is quite useful for accomplishing exactly that.

Furthermore, the light-year has a built-in assumption about what year is used. According to Wikipedia: “As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year.” My favorite engineering reference for unit definition has this entry:

Buzzed-Light-YearThe options given for a light year length are:

Anomalistic Light Year: 9.460 980 Petameters

Julian Light Year: 9.460 730 Petameters

Siderial Light Year: 9.460 895 Petameters

Tropical Light Year: 9.460 528 Petameters

There are two questions that in my view are rather separate: 1) How far away is an object based on a linear measurement? 2) How long does it take an electromagnetic wave to get from there to here (or vice-versa)? Astronomers might argue that the light-year is really the best description in their view, but when one looks at a star there is no way to really grasp the amount of time or distance. They all look very similar. The first question one probably wants to know is: “how far is that star?” rather than “how long does an electromagnetic wave take to arrive?”

ShimmerThere is another apparent problem. Suppose I were to ask: what is the radius of the Sun? One might immediately say it is 696 000 Kilometers, but I could also argue that it’s about 100 000 light-years, or 1000 light-centuries in extent! Light does not always travel at 300 000 meters/second, it can travel slower than this value when a dielectric medium is present, such as plastic, glass or gas. It takes a photon about 100 000 years to make its way from the Sun’s center to its surface. The photon also loses energy (changes frequency) as it works its way through stellar plasma, but light is a general term for an electromagnetic wave, and its frequency is not specified by astronomers. They just say “light,” so if a photon is just one millimeter inside of the event horizon of a black hole, would its distance to any other body in the universe, in light years, be infinite?—or even possess an imaginary distance?  Is this a legitimate use of a light-year as a “measurement unit?” Well, no, it is not. Astronomers define a light-year in a vacuum, but Wikipedia also calls it an informal unit and claims it is a length, and should not be confused with time—even though time is in the name of the “unit.” The light-year reminds me of Saturday Night Live’s Shimmer Floor Wax, it’s both a floor wax and a dessert topping. Some astronomers have been less than enthusiastic about the light-year as a “unit.” According to Wikipedia:

The light-year unit appeared, however, in 1851 in a German popular astronomical article by Otto Ule.[18] The paradox of a distance unit name ending on year was explained by Ule by comparing it to a hiking road hour (Wegstunde). A contemporary German popular astronomical book also noticed that light-year is an odd name.[19] In 1868 an English journal labelled the light-year as a unit used by the Germans.[20] Eddington called the light-year an inconvenient and irrelevant unit, which had sometimes crept from popular use into technical investigations.[21]

Astronomers define a light year as the distance light travels in a year in a vacuum; but there is another unit which is defined as the distance light travels in a given amount of time in a vacuum. It is the meter, and it’s the base linear measurement value of the metric system. The meter does not have any unit of time in its name, and so it would alleviate the time confusion immediately. Astronomers who might not be familiar with this unit can convert it to 3.33564 light-nanoseconds for clarity. The metric system also has a unique unit of time, the second. One can use metric prefixes with it to describe intervals of time. It’s about time, it’s about space, but only one at a time, unless it’s a relative place.

Postscript: And Then There Were Two? I have been informed that Myanmar has quietly continued to pursue metrication:

Bonfire of The Vanity Units

HH-GrowlerBy The Metric Maven

Bulldog Edition

John Bemelmans Marciano gave a lecture on CSPAN’s BOOK TV (2014-08-12) to promote his book Whatever Happened To The Metric System?, which neither answers the proposed question, nor discusses the metric system itself. In his lecture, Marciano makes straw-man statements like:

The reason  that the metric system was needed in the first place was that decimals aren’t such a great way to divide things. Have you ever tried dividing a pizza into ten slices or five slices it’s not very easy. It’s really easy in four, six, eight, if you have a Sicilian pie you might do it in twelve or sixteen. … the only thing that ten is good for is counting on your fingers. ….they’re excellent for tallying, when you have to have a running tally of something, but they’re just not good for fractions.

Anyone who casually is acquainted with arithmetic will see that decimals are one of the most useful creations of mathematics. They are straightforward in magnitude, whereas fractions are an incomplete thought. The only way to further simplify numerical expression is with measures that can eliminate decimal points in everyday life. The metric system does this with grams, milliliters, and millimeters. The use of integer values in place of fractions is an upgrade from an abacus to a modern computer.  Marciano seems to have done little research on the metric system, or is willfully ignorant.

Marciano continues with both a revisionist and radically incomplete history of the metric system.  “So whereas decimals were supposed to make math and currency and everything available to everybody, it actually just made it available only to people who were really truly well educated.” Marciano appears to be implying that decimals were created and adopted so the power elite can rule over the innumerate populace. They are so complicated of a concept that only those who are highly educated can comprehend them? How on Earth does anyone use decimal currency? For Marciano, metric is not a commie plot, but a capitalist plot?  Decimals are apparently an antidemocratic force in our society?

He goes on to argue that the return of kings to Europe was very sad for John Quincy Adams “who had about the biggest crush on the metric system of anyone.” That statement is amazingly off the mark, perhaps by a few Gigameters? You are invited to read my essay about John Quincy Adams, and you will find that JQA had nothing remotely like a “crush” on the metric system, which is well documented in his own words. John Quincy Adams was the John Bemelmans Marciano of the 19th Century. Marciano clearly did not spend any time reading John Quincy Adams’ Report on Weights and Measures, or he would have known this. But this does not stop Maricano from interpreting it: “He [JQA] actually wrote, while he was Secretary of State, the greatest work ever written about measurement, and he talked about all the great things about the metric system….” JBM’s assertions are clearly at odds with JQA’s Report.

Marciano protests too much when, after he was asked by an audience member if he is anti-metric, he states:  “I am pro-metric, but I am also pro-customary measures. … I think we should keep it all.”

I see this statement as completely disingenuous. I’ve read Marciano’s book and his online editorials, listened to his NPR interview and this BookTV presentation. Marciano’s pro-metric assertion is doublespeak. Keep it all? Is Marciano for everyone choosing an old measure and using it if they want?

Marciano then states, to prove his pro-metric bone fides, that he thinks liquid measures should be metric. Marciano then reaches down and produces a bottle and states:

One fascinating thing of measurement is the growler. The growler started up… the growler is actually an old system of measure that was revived .. I think they were Wyoming brewers who..who restarted it. A growler is half a gallon .. its filled with four pints .. what I think the growler speaks to is that the craft brewing movement came out of the U.S. and it’s… I think the reason that the pint gets to be used is …it seems like this more honest system of measurement. Ben and Jerry’s when they wanted to have sort of a more .. homespun they revived the idea of using a pint for ice cream .. a pint really sounds like ..it comes right off of the farm. …almost all of our dairy is still in — solely in customary measures.  ..when you realize it’s still ingrained in people’s minds is when you actually buy in a whole unit. You’re not just buying 14 ounces of something you’re buying a pint of it, a quart of it, you’re buying a half-gallon of it. If it’s just something like 14 ounces or you know point four six milliliters we just pay no attention to it.

Growler-FixedWell, Marciano stops there when talking about liquid measures. I don’t see any argument using actual numbers with the metric system, or where he thinks one should use metric units for liquid measures. (Perhaps he could mention mis-dosages?) He does not follow through with his assertion that he is pro-metric for liquid measures. Marciano instead explains why people in the U.S.  just love the current mess. Marciano’s final statement  about 0.46 milliliters could be taken as hyperbole for how clueless people are about measures, or worst of all, it could be he is numerically clueless that 0.46 mL is 460 microliters, a value that would probably not be found on a store shelf.


— click to enlarge

What caught my attention more than all of the muddled assertions, was the notion of a growler. When I first heard Marciano discuss this unit, I figured it was just one more of the thousands and thousands of confusing pre-metric units that have existed in history. I have a number of engineering references for measurement units, and none of them mention a growler. I looked on Wikipedia, no entry for a measurement unit called a growler exists, but there is an entry under “beer bottle” with a reference to 64 ounce or 32 ounce growlers. The 32 ounce is sometimes called a howler for half-growler. This smells like marketing, and not measurement. The growler is almost certainly a made-up vanity unit for the microbrewing industry, which does not see the irony in using a metric prefix for self-identification and then marketing in Ye Olde English.

The growler is just a vanity unit, made up for marketing purposes. It appeals to novelty/pseudo-nostalgia and has no standing for measurement. It’s no different than using coffee speak to order  a tall cafee au lait dry single skinny. A growler is simply a hipster vanity unit.

There is a long worn pre-metric unit for one-half gallon. It is the pottle, and it is also equal to 32 gills to make the quantity plain for my U.S. readers who we can assume understand English measures and not metric. As Marciano is for all of them, perhaps we should include all gills:

Gills-1850This reference from 1850 helps us to understand this new and important faux unit—the growler—even if there is no entry for it. One notes that U.S. measure is Great Britain’s old measure. Because when it comes to measurement, Marciano is for all of them, we should include all known growler quantities. Assuming a 32 gill growler:

  • British Growler = 4545 mL
  • Irish Growler = 3263 mL
  • Scottish Growler = 3389 mL
  • U.S. Growler =  3785 mL

So the growler varies from 3.26 liters to 4.55 liters. Yes, clearly the old measures are, as Marciano asserts, much more honest. Perhaps we should create a unit called the Enron?

I’m very surprised that an expert on measures like Marciano missed pointing this out to his audience, especially when following up on his assertion that he saw the metric system as a better idea for liquid measures. Why the imaginary growler? Perhaps pottle doesn’t have the marketing appeal of a growler and sounds too much like what one does after drinking said imaginary unit. Marciano likes to use Tom Wolfe as an A-list metric opponent, but Marciano, despite his protestations, seems to relish representing contemporary Bonfire of the Vanity Units.

Related essays:

John and the Argot-nauts

Whatever Happened to the Metric System?


A member of my Sunday morning coffee klatch came across nothing but metric signage at a prison museum in Deer Lodge Montana. He took a photo of the sign which explains what a meter is for visitors who are unfamiliar with it: