(Note: Where bold numbers are used the units are exact.)
How many feet are in a mile, how many square feet are in an acre, and how many cubic inches are in a gallon? These are the units used to tell you how far it is from New York to LA, the amount of land you own, and how much milk you're buying. Still, you're average American wouldn't know that the answers are 5,280, 43,560, and 231. Yet, there are people vehemently against the "metric" system. This is what Daniel said:
“Hundreds of millions of liters”?????? What in blazes is this talk about LITERS????? You claim to be an American, so TALK American! The stupid, filthy, idiotic, no-good metric system has no place in this country, and you should be ashamed of yourself for using it. (And just to clarify, I am most emphatically NOT joking.)For the past two decades I've worked on projects that used USsom, SIdU, and even some that combined the two. That experience has led me to prefering SIdU over USsom for several reasons. It has also given me the impression that those against SI being used in the US use the measurements but don't work with them. When they are used the person only thinks of them as numbers, but when you work with them you have to know what the numbers actually mean.
One way to find out how important a number is to a particular person is to ask them. Ask a layman how long an inch is and they'll hold their fingers a distance apart, and if I don't have a scale or measuring tape handy I'll do the same thing. However, if you ask someone about a foot, yard, and mile afterward you'll get other references. For a foot you'll usually get hands held a distance apart, and for yards you'll either get the answer of "three feet" or hands held to what the person thinks is three times the distance they held their hands apart for a foot. If you ask them about a mile, then you'll usually get an answer of two locations that they think are a mile apart. With the mile they may be guessing, or have used an odometer on their car to find out.
However, I work with measurements. If I don't have a scale I'll hold my fingers apart as an approximation of inches, but from there on I'll give you exact numbers. A foot is twelve inches, a yard is three feet, a mile is 5,280 feet. Unless I have a scale, yardstick, or map handy, those are the answers you'll get from me. To go further, I know that the index of my right hand is just a little over 3.5" or about 90mm, and that a casual gait will give me a distance of approximately 2.7 feet or 0.82 meters. Why do I know these things?
I know the approximate length of my index finger out of curiosity, but I once worked for a mining company and had to take measurements in feet. A couple of times I forgot the wheel that I used to measure the distance, and took the time to measure my stride so if it happened I could use my steps along with a calculator to give me a distance. I did this by measuring five different distances with the wheel, and then pacing the same distances. The 2.7 feet is accurate enough to measure the distances well within the five percent that was required of my job. I preferred to use the wheel for better accuracy, but knowing the length of my stride meant not having to go back to get the wheel if I did forget it.
Now, what does all of this have to do with the SIdU, most commonly known as the Metric system, and why does it make me prefer it? The answer is "ease of use". The converting of one SI unit to another only involves shifting the decimal to the left or right a certain number of places. Converting millimeters to meters means shifting the decimal place three places to the left which means my 90mm finger is 0.090 meters long. I can do that easily in my head, but converting that 3.5" into feet is more difficult. To do that I have to divide 3.5 by twelve. Try doing that in your head? The answer actually is .291666667~, and that leads me to my next issue with the USsom.
If the lower unit of the metric system is an interger not divisible by 10, then the worse you'll get is a number that has to go out to the number of decimal places required by the conversion. So if something is 9mm, then it is 0.009 meters. At 10mm you can elimiate the extra decimal because it's 0.01 meters. Now, if my finger was half inch shorter, 3" long, I could have told you that it is 0.25 feet, or 1/4 of a foot. However, what if it was a half inch longer? 4" is 1/3 of a foot, which is 0.333333~ (and the threes repeat out to infinity). That's why architects use [feet]'-[inches]" in their drawings. If a distance is 6 feet you'll see a dimension that says 6'-0", but if it's six feet one inch you'll see 6'-1" not 6.1667'.
SIdU has another advantage over USsom. Conversions from USsom to SIdU. This is why I noted that all bold numbers are exact. When converting USsom to SIdU the numbers come out exact. For length the number to remember is 25.4. That's how many millimeters are in an inch. So an inch is 25.4mm, a foot is 304.8mm, a yard is 914.4mm, and a mile is 1,609,344mm. Once you have those, it's easy to convert them to the appropriate SI unit. Say you don't like you're units being over 100, then they become 25.4mm, 30.48cm, 0.9144m, and 1.609344km.
So converting USsom to SIdU doesn't have any conversion issues, but what about the public? They're used to seeing USsom in their daily lives. Roadsigns will read "Cincinnati 120" which tells them miles, Kroger sells milk by the gallon, and Lowes sells 2x4s. It's even called the US system of measurement, so what about the patriotic aspect?
My answer to this is pretty standard for these sorts of arguments.
Me: "So?"In the case of mileage, the distance is still the same, all that changes are the units used to measure it. If the car is doing 60mph then the 120 means it'll be about 2 hours before you reach Cincinnati. Still, are you going to the exact spot that mileage is referring to, or is Cincinnati just the closest point to your destination? What if you're doing 70, how does that change it? (Hint, it shaves about 17 minutes off your time... or about 1 hour and 43 minutes.) People who will use the numbers more often, such as truck drivers, will adapt within a fairly short time. Everyone else will still guess wrong on when they're going to get where they're headed.
What about milk, then? How difficult will it be if it goes from 1 gallon to about 3.8 liters? About as difficult as it is buying about .53 gallons of Coke, Pepsi, Mountain Dew, or whatever other soft drink/soda/pop that they buy. In case you haven't figured it out, .53 gallons is about 2 liters. Gallons are nothing more than cubic inches, 231 actually, and liters have been used for automotive engine displacement for several years now. Motorcycles engines have used cubic centimeters for even longer. In all the cases, it only takes a number comparison to tell you what you want to know. How much am I getting for the price I'm paying. If you know how to shift a decimal, then you can figure that out much easier with the SIdU than with the USsom.
Now what about carpentry? How will the SIdU affect 2x2s, 2x4s, 2x6s, 4x4s, etc.? Not really that much. Those are just numbers to tell you the ratios of one dimension to another, and further they aren't even accurate. Where you see a two the dimension is actually 1.5" if the board is dry (1.5625" if green). 4 is actually 3.5", 6 is 5.5", etc. With that in mind the SI equivalents could be 50x50, 50x100, 50x150, 100x100, respectively, with no affect on the consumer. The new numbers would even be marginally more accurate than what is used today, because 1.5" is 38.1mm and 50mm is closer to 38.1 than 2" [50.8mm].
That leaves the patriotic aspect, after all it is called the "US" system of measurement. I honestly don't see how the ideals of our country would dictate that we stick with an outdated and overly complicated system of measurement. Such narrow thinking would keep the US from competing in the global economy, and as such many of the projects I work, and have worked, on use SI units. Mostly to avoid errors that can happen when conversions aren't done. With todays CAD software it's actually extremely easy to convert something done with USsom into SIdU. The conversion even works so well that anyone with experience in both can see when a part is being used in SIdU that was originally done in USsom.
Those who are so opposed to SIdU do not understand the past, and are disconnected from the present. US automakers, industrial engineering firms, consumer goods companies, and NASA us the SIdU without any adverse affects on the American public. It allows us to communicate effectively with non-domestic vendors and partners, compete in the global economy, and also spend less time doing conversion calculations. So for those of you who think the "stupid, filthy, idiotic, no-good metric system has no place in this country", I have news for you. It's already here, and has been for far longer than you realize. You may not be joking, but you have definitely, if unwittingly, made yourself a joke.
