Category Archives: International Standards

Don’t Assume What You Don’t Know

Posted on by

By The Metric Maven

Bulldog Edition

“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”

– Mark Twain

When I first learned about viruses, I found them terrifying. They were as terrifying as any plot in a science fiction novel. They were unimaginably small. The virus shown had a set of “legs” which it could use to attach itself to a cell. It would then inject material through the cell wall from a head that looked like a gem. The cell would then become a zombie and make more viruses until it exploded like a balloon popping and the new viruses were scattered everywhere to find new cells. What I took away from the grade school lesson was that viruses were so much smaller than bacteria, they were like comparing an m&m to a basketball.

During one Summer break in college I read One two three… infinity by George Gamov. The book was published in 1947, but remains a classic. In one section of the book, Gamov explains that bacteria like typhoid fever has an elongated body “about 3 microns (µ) long, and 1/2 µ across, whereas the bacteria of scarlet fever are spherically shaped cells about 2 microns in diameter” A footnote states: “A micron is one thousandth of a millimeter, or 0.0001 cm.” It would not be until 1960 that the micrometer would become an accepted term.

Gamov explains there are a number of diseases such as influenza “..or the so called mosaic-disease in the tobacco plant, where ordinary microscopic observations failed to discover any normal sized bacteria.” Clearly something existed which was transmitting disease, but what was it? “…it was necessary to assume that they were associated with some kind of hypothetical biological carriers, which received the name virus. The use of ultraviolet light and the development of the electron microscope allowed researchers to finally see viruses and describe their structure.”

Above I have reproduced the prose and type used by Gamov. You will note that he just uses the Greek letter µ to represent a micron, which is, of course, a micrometer or µm. Gamov continues:

Remembering that the diameter of one atom is about 0.0003 µ, we conclude that the particle of tobacco-mosaic virus measures only about fifty atoms across, and about a thousand atoms along the axis.

In modern terms:

Typhoid Fever Bacteria:  3000 nm x 500 nm
Scarlett Fever Bacteria: 2000 nm in diameter

Tobacco Mosaic Virus:  280 nm x 150 nm
Influenza Virus:  100 nm across.

Atomic diameter: 0.3 nm diameter

Excellent Graphic from New Scientist “Pandora Challenges the Meaning of Life” (2013-07-13) pg 10 all in nanometers — click to enlarge

Viruses are clearly much much smaller than bacteria, and much much harder to study. But then in 2003, an organism which first appeared to be bacteria, because a common test indicated it was, was instead discovered to be a virus. It was dubbed a Mimivirus or microbe-mimicking virus. This virus has a diameter of 750 nanometers. This is just plain gigantic. Suddenly researchers found “giant” viruses everywhere! Why was this? These viruses are really big—and we have much better microscopes and tools than existed in 1947, how could it be that only in the 21st century anyone identified them? An American Scientist article from 2011 entitled Giant Viruses explains:

Most giant viruses have only been discovered and characterized in the past few years. There are several reasons why these striking biological entities remained undetected for so long. Among the most consequential is that the classic tool for isolating virus particles is filtration through filters with pores of 200 nanometers. With viruses all but defined as replicating particles that occur in the filtrate of this treatment, giant viruses were undetected over generations of virology research. (Mimivirus disrupted this evasion tactic by being so large it was visible under a light microscope.)

It was assumed that viruses were smaller than 200 nanometers, so they were filtered out. No one even thought to look for them because it was something “what you know for sure that just ain’t so.” that precluded researchers from seeing this virus for over fifty years. In 2014 researchers resurrected a 30 000 year old virus from Siberian permafrost which is the largest thus far discovered. It is called pithovirus sibericum and measures 1500 nm in length and 500 nm in width, which approaches the dimensions of the Typhoid and Scarlett fever bacteria cited by Gamov.

In the 1980s, ground based British researchers in Antarctica noticed a large depletion of ozone above them. The numbers were so low, there was concern that the instrumentation was faulty. Satellite measurements did not reveal the ozone depletion which caused a considerable conundrum. The numbers were so low that according to folklore, the computer software had a lower limit and threw out the bad data. The story is difficult to pin down and a bit apocryphal, but it illustrates what I’ve seen in my own career.

When I was first creating computer models of antenna radiation using a computer method called FDTD, I calculated radiation patterns. There are two different values to calculate, one is large and the other smaller.  An antenna was fabricated, and measured based on my analysis. The large value was measured to be almost exactly the value expected. There was a confusion on my part when the analysis showed a clearly defined smaller valued radiation pattern, but the measurements indicated no antenna pattern was present. When I showed the person who had written the program for the measurement chamber this anomaly, he remarked “That’s so low, it’s meaningless, I just set the value to the bottom of the expected range.” I had to convince him to change the computer code so it would output the actual numbers, and to his surprise, the smaller data was far, far more accurate than he had imagined.

This brings me to a ubiquitous metric system fallacy that seems rooted in the heritage of our Ye Olde English Arbitrary Grouping of Weights and Measures or Ye Olde English. This fallacy Sven and myself call “The Implied Precision Fallacy.” It is the idea that one should decide what measurement units are to be used based on a prejudicial notion of what the magnitude is expected to be measured, and the expected measurement error. It also implies that if you measure further than this, you are implying you are measuring to that precision.

This fallacy may have its roots in the past, when the available precision of a measurement device or construction device (like a mill or lathe) might have limited how far down one could measure or fabricate to a given accuracy. If a person had a problem measuring or constructing to a particular precision and accuracy because of tooling limitations, one might be tempted to argue not to bother with places beyond what they thought was possible.

Unfortunately this argument could be turned around into a rationalization that if that’s the best one can do that’s the best one actually needs. I was told many times, by many school teachers to choose medieval units which reflect expected precision, and if I used smaller ones that this was very poor practice. It was overkill. The size of the units chosen would imply the precision of the measurement, so use as large of units as possible. As you see when the size of units are used a priori as an argument of precision, then they are a chosen limitation, and not a well informed limitation. They are in fact a guess.

I have run into many situations in my career where data looks like noise, and then using signal processing, useful information is obtained. The GPS signal you use to guide your car trips is well below the noise level at that frequency. It is like standing in the top row of a football stadium and trying to hold a conversation with a person with a person on the other side of the field also on the top row while the crowd cheers. Impossible—right? Well, perhaps not. Signal processing can do amazing things, but if you argue there is no way to make a measurement precise enough, you will not. It is a psychological self-imposed measurement limit, not a technical one.

This brings me to the measurement of people’s height and the mass of babies. I have been taken to task for arguing that height should be measured in mm, just like lengths are in the Australian construction industry. Some commentators argue that this is too much precision, that a person’s height changes so much that millimeters just have too much precision to have any meaning. There is no use taking measurements which are calibrated to millimeters, because we already know we don’t need them. This is a very platonic argument. It is also nonsense on a number of levels. First, the data itself should reveal where the precision no longer exists. If one can show that a certain set of digits on the right are randomly distributed, then one can obtain an implied measurement precision, but that is not the end of the story. Even digits which appear to be random may contain information which may be extracted. I’ve never seen a situation where measurements have been too precise, and led people to miss an effect, but I have seen situations where they have been masked by truncation. Measuring a person’s height as 1753 mm does not assault good technical practice, it is an example of it. One can always write this value as 1.75 meters immediately just by inspecting the millimeters, but one has taken a simple integer and needlessly introduced a decimal point. The two representations use the same number of symbols.

The grouping of three for numbers appears to be of great utility in our society. From one thousand (1,000) to one million (1,000,000) to one billion (1,000,000,000), these values have been designated in groups of threes long before I made my appearance on this planet.  The breaks in metric prefixes, are at the locations of the commas. In other countries only a space is used above four digits: 1000, 1 000 000, 1 000 000 000 (one can use a space with four digits also—it’s just not my preference).  This is also done in many US numerical analysis references.

Pat Naughtin, in his TEDx Melbourne  lecture on 2010-03-13 discussed a scale which measured the weight (mass) of babies. The baby would wriggle and it would require the device to take large numbers of measurements and statistically extract its mass. The precision and accuracy of this scale was to within a gram. The weight of a baby is supposed to increase with time. A decrease, even a very small one, could indicate a potential health issue.

Should the baby have an infection, accurate knowledge of its mass is important so a properly proportioned amount of medicine can be prescribed. Naughtin points out that yet again there is no measurement policy in this instance, and no one in charge of one. Naughtin argued there is a potential danger when babies are measured in Kilograms, and rounded to the nearest tenth of a Kilogram, which is the accepted practice in Australia. The use of a decimal point, and rounding, creates numbers which are decanted of information. The number is too close to unity for a clear understanding of changes in its magnitude. Using grams allows for one to eliminate fractions—decimal or otherwise—and compare simple integers.

Years ago when I lived in Montana, I encountered shade tree mechanics, small engine mechanics, construction contractors and others. One phrase which seemed to be ubiquitous was:

“He’s the kind of guy that will measure something with a micrometer, mark it with chalk and cut it with an axe.”

It showed a common understanding that over-precision does not hurt one, and a person who would throw it away is not good at his profession, be it mechanic, welder, contractor, or any other skilled vocation. The Australian construction industry has saved large amounts of money by measuring in millimeters. They have no need for a decimal point, and the numbers are simple. The argument that measuring a person’s height in millimeters, or a babies weight in grams is “too precise” is a cultural argument, not a technical one. Arguing that lots of people perform a measurement, or an authority like the EU or the medical profession has endorsed it is an argument from authority.

In my essay Metamorphosis and Millimeters, I point out that for thousands of years people had created bee hives which were made of clay. They had to be destroyed in order to obtain honey. It was only in the 19th Century that an American inventor had the temerity to question this dogma, and created the modern bee-hive. Common usage over a long period of time does not imply that common usage is optimum. This is a version of a technical Darwinism argument that is used by anti-metric people as a straw man cudgel. It has been increasing measurement precision (and accuracy) which has allowed the creation of a modern technical society and is at the forefront of scientific discovery. Arguing otherwise is arguing against all the benefits increased measurement accuracy has provided. There is no “common person’s measurements” and a separate set of “scientific people’s measurements” there are only precise measurements.

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

Updated 2015-01-21

Taking The Metric Fifth

Posted on by

By The Metric Maven

Bulldog Edition

Last year I attended a post-Thanksgiving social function. One of the hosts was busy in the kitchen creating some manner of confection with bourbon in it.  I was suddenly sought out as the resident measurement person and this conversation occurred:

Host: “How much is a fifth of whiskey?”

MM: “There is no such thing anymore, it’s 750 mL. I believe it used to be one-fifth of a gallon.”

The Host clearly saw my answer as completely unsatisfactory, apparently very difficult to believe, and asked to borrow a smart-phone so he could look on the internet. After some conversation with others and my directly asking, he indicated I was right. It just seemed like too much liquor to put into the recipe.

The fifth is a surprisingly strange volume—even for US Ye Olde English Units. The fifth was equal to 1/5 of a US gallon which is equal to 4/5 of a quart which is also equal to 25 3/5 fluid ounces which is 757 mL.

Whenever my friend Lapin is confronted with something he said in the past which after some reflection appears incoherent, he generally states: “I don’t know, I must have been drunk at the time.” The spirits industry apparently wasn’t when they chose the fifth. According to Amy Richards Krumich, who for a short time wrote a metric blog called Penny Wise and Pound Foolish, the origin of The Fifth is thus:

That size [750 mL] was chosen [by Europe and the US] because it contained approximately the same volume as the “American Fifth” (a fifth of a gallon) whether it was wine or hard spirits. The fifth had been invented by the spirits industry many years before to avoid being taxed, since taxes were assessed for quarts or larger volumes of wine or spirits.

So the quantity was invented to avoid liquor taxes? That seems likely.

One of the strangest occurrences in the 1970s, was that one industry apparently didn’t get the memo that the metric system in the US is very, very, very voluntary. It was the hard liquor and wine industry. This is an amazing singularity, and is offered constantly as an example that we are “going metric soon” because the alcohol manufacturers have done so. Unfortunately US metrication is always a Friedman Unit away, but well-meaning metric enthusiasts cite it as evidence of current change. In his 2004 book The United States of Europe T.R. Reid states on page 5:

Because the united Europe is the world’s largest trade market, it is the “Eurocrats” in Brussels, more and more, who make the business regulations that that govern global industry. There’s a reason why the quintessential American whiskey, Kentucky bourbon is sold today in 75 cl bottles. It’s not because American consumers suddenly demanded to sip their sour mash by the centiliter

Later on page 233:

No matter how efficient and and logical metrics might be, we still prefer our inches and feet, ounces and pounds, yards and miles. But American food and drink labels today are going metric. You can’t buy a “fifth” (that is, a fifth of a gallon) of American Whiskey anymore; all liquors are sold by the centiliter today, because that’s how the European market demands it. Instead of a “fifth” the standard bottle now is 70 or 75 centiliters, which turns out to be a few sips short of a fifth of a gallon. It is because of the European regulatory influence that Americans routinely buy 2-liter bottles of Coca-Cola….”

T.R. Reid like other US citizens knows about as much about the metric system as most Americans do about cricket. Centiliters! Seriously? Milliliters are what are used in enlightened metric countries—like Australia. The Eurocrats in Brussels forced the US into metric booze?–and two liter bottles of soda?

Here is what Wikipedia states about the “Metric Fifth”:

During the 1970s, there was a push for metrication of U.S. government standards. In 1975, the Bureau of Alcohol, Tobacco and Firearms, in cooperation with the Distilled Spirits Council of the United States, proposed six metric-standard bottle sizes to take effect in January 1979 and these standards were incorporated into Title 27 of the Code of Federal Regulations.[7][8] These sizes are 50, 100, 200, 375 (355 for cans), 500 (until June 1989), 750, 1000, and 1750 mL.

The mystery is that this change occurred at all. The actual change for liquor occurred in 1979, at the height of the “US faux-metric-conversion.” It is my understanding that the European Union was founded in 1993. So Brussels “forced” 750 mL bottles of Whiskey on the US approximately 14 years before the EU was founded? The two-liter bottle was introduced by Pepsi in 1970—and seemingly has zero to do with any proclamations from Brussels at the end of the 1960s—unless those are some supernaturally powerful Eurocrats!

In recent years I’ve been pleased to see bottles of soda which are 500 mL and 1 liter, but I’ve also seen pints, quarts and numerous variations of Ye Olde English proliferate with them. It seems very likely this mixture of odd sizes is somehow used to “profit from the yardstick.” If they were all in metric, and in milliliters, there would be no wiggle room. You would see the difference between a 300, 350 and 355 mL can of anything immediately and easily compute the price per mL. Market Darwinism embraces the proliferation of measurement units, as it has throughout history.

There are many aphorisms about the metric system in the US that I believe cause complacency. One statement is “We’re over 50% metric in the US.” I’ve never been able to trace down any reference, or any study upon which this assertion could “hold water.” The fact that booze is sold in metric, and that we have two-liter bottles is also offered as contemporary evidence of change—every decade since the change occurred. This is change which actually occurred over 35 years ago for liquor and 44 years ago for two-liter bottles. It’s time to face up to the fact that metric usage in the US is stagnant, and waiting for metrication to magically happen without government intervention is a fools errand. Asserting stagnation is actually alteration only causes procrastination. Waiting doesn’t produce change, nor does quaffing a metric drink of alcohol move us one millimeter closer to a metric US. A person who asserts otherwise?—-“must have been drunk at the time.”

Related essay:

The Singular Beverage Experience

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:

The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.


The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.


The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.