City-Data Forum The U.S., the metric system , and soccer (cd)
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11-01-2012, 05:32 PM
 Location: San Francisco 9,033 posts, read 8,382,467 times Reputation: 5652

Quote:
 Originally Posted by rcsteiner The UK still uses miles and miles per hour on their highway signage, so it's not like the US is alone in sticking with English measurements.
UK weather maps are very odd -- they feature temperatures in °C and wind speeds in mph.

11-01-2012, 06:03 PM
 Location: Westwood, MA 3,477 posts, read 4,364,237 times Reputation: 4477
Quote:
 Originally Posted by pch1013 Actually, the metric/SI system was originally based on the most natural unit of all: the size of planet Earth. A meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole. A hectare is 10,000 square meters. A liter is one-tenth of a meter, cubed. A kilogram is the weight of a liter of water. Zero Celsius is the freezing point of water; 100 Celsius is its boiling point. What could be simpler or more logical? Granted, the definitions that were precise enough in the 1780s have been supplanted by extremely precise ones based the speed of light -- or, in the case of the kilogram, on the weight of an actual model kilogram stored in Paris. But originally they were far less arbitrary than the inch, foot, mile, acre, or pound.
The SI, like all units, certainly do come from something, but the something they come from is arbitrary and all of them are so imprecise as to no longer be used as the basis for the unit anymore. The meter, for instance, in reality has only historical relation to the Earth (it's now defined as the speed of light times some fraction of a second).

Using the equator-pole distance is certainly arbitrary--it's difficult to measure, not particularly easy to conceptualize, and not very useful for measuring things on a human scale. Why choose the equator-pole distance instead of the equatorial circumference, or the semimajor axis, or the average or largest or smallest distance to the sun? If the fundamental unit is that distance, though, why did they divide by 10^7? Say what you will about the inch, the foot, and the yard, but they're tailor made for measuring things about the size of a thumb, a foot, or a stride.

The advantage of SI is certainly not that the units are any less arbitrary than other systems, it's simply that it's decimal, nearly universally accepted as national standards (the inch is in fact defined as 25.4 mm).

Natural units are units defined in terms of physical constants, not arbitrary things in nature like the dimension of a planet or some particular chemical. Those units are way too small to be generally useful, but they are considerably more fundamental than SI.

11-01-2012, 06:45 PM
 Location: Washington D.C. 552 posts, read 933,257 times Reputation: 773
Quote:
 Originally Posted by pch1013 Actually, the metric/SI system was originally based on the most natural unit of all: the size of planet Earth. A meter was originally defined as 1/10,000,000 of the distance from the equator to the North Pole. A hectare is 10,000 square meters. A liter is one-tenth of a meter, cubed. A kilogram is the weight of a liter of water. Zero Celsius is the freezing point of water; 100 Celsius is its boiling point. What could be simpler or more logical? Granted, the definitions that were precise enough in the 1780s have been supplanted by extremely precise ones based the speed of light -- or, in the case of the kilogram, on the weight of an actual model kilogram stored in Paris. But originally they were far less arbitrary than the inch, foot, mile, acre, or pound.
Wow very insightful

11-01-2012, 06:56 PM
 Location: San Francisco 9,033 posts, read 8,382,467 times Reputation: 5652
Quote:
 Originally Posted by jayrandom they're tailor made for measuring things about the size of a thumb, a foot, or a stride.
Except that thumbs, feet, and strides come in many different sizes... Earths do not.

Not to mention the fact that 10 is a much less arbitrary multiplier than 3, 12, 180 (degrees from freezing to boiling on the Fahrenheit scale) or 5280. Almost every human has 10 fingers. What does 5280 relate to?

Another benefit of the metric system is that anyone in possession of the facts I listed also knows a few other things, e.g. the circumference of the Earth and the weight of a certain amount of water. How many people can easily rattle off the weight, in pounds, of a gallon of water?

11-01-2012, 08:45 PM
 Location: Westwood, MA 3,477 posts, read 4,364,237 times Reputation: 4477
Quote:
 Originally Posted by jayrandom The advantage of SI is certainly not that the units are any less arbitrary than other systems, it's simply that it's decimal, nearly universally accepted as national standards (the inch is in fact defined as 25.4 mm).
Quote:
 Originally Posted by pch1013 Except that thumbs, feet, and strides come in many different sizes... Earths do not. Not to mention the fact that 10 is a much less arbitrary multiplier than 3, 12, 180 (degrees from freezing to boiling on the Fahrenheit scale) or 5280. Almost every human has 10 fingers. What does 5280 relate to? Another benefit of the metric system is that anyone in possession of the facts I listed also knows a few other things, e.g. the circumference of the Earth and the weight of a certain amount of water. How many people can easily rattle off the weight, in pounds, of a gallon of water?
I'll say it again, the consistent base of 10 is a definite advantage of the metric system. As for arbitrary, I think we see arbitrary in a different way. 10 is not a particularly attractive number from a practical point of view-- it's only factors are 2 and 5 which are small but fairly widely separated. 2 is a natural base from the perspective of being first; 3 is the optimal base in terms of efficiency; 6 is nice because it is the product of the two primes; 12 has a large number of factors for its small size (2, 3, 4, 6); 5280 is annoying

I mention that thumbs, feet, and inches only because we all have access to them and can get a rough idea of what the correct measurement is using body parts. They only thing you can estimate with 1/4 of the polar circumference of the Earth is the Earth.

And having the density of water be about 1000 kg/m^3 (I personally roll with SI, none of this 1 kg/dm^3 stuff) is definitely a benefit of SI. I suspect that the number of people that can rattle off the density of water in lb-m/ft^3 (it's 62.4) or the weight of a gallon of water (it's 8.34 lb-f) is a large subset of the people who need to know the weight of water in US customary units. I don't know if that's a smaller or larger set who know that the lb is both a unit of force and a unit of mass and that you have to be careful converting the two.

11-01-2012, 08:47 PM
 Location: Somewhere in northern Alabama 16,869 posts, read 51,398,709 times Reputation: 27761
Quote:
 Originally Posted by pch1013 Except that thumbs, feet, and strides come in many different sizes... Earths do not. Not to mention the fact that 10 is a much less arbitrary multiplier than 3, 12, 180 (degrees from freezing to boiling on the Fahrenheit scale) or 5280. Almost every human has 10 fingers. What does 5280 relate to? Another benefit of the metric system is that anyone in possession of the facts I listed also knows a few other things, e.g. the circumference of the Earth and the weight of a certain amount of water. How many people can easily rattle off the weight, in pounds, of a gallon of water?
Not another one. <shessh> A pint is a pound, the world around. two pints in a quart(er) of a gallon of water. Eight pounds. In commerce, items are commonly divided into halves, quarters, or thirds. Twelve does that. Ten does not. Remember that the French also wanted ten hour days. Fixation on toes and fingers can be a sign of mental illness.

11-02-2012, 04:43 PM
 Location: San Francisco 9,033 posts, read 8,382,467 times Reputation: 5652
Quote:
 Originally Posted by harry chickpea Fixation on toes and fingers can be a sign of mental illness.
I see, so were the Brits better off when their pound had 20 subunits and 240 sub-sub-units instead of the current, mentally deficient 100?

11-02-2012, 07:46 PM
 Location: Somewhere in northern Alabama 16,869 posts, read 51,398,709 times Reputation: 27761
They were the colonizers that defeated Spain, France, Portugal, and Germany, weren't they?

The metric system came into the forefront during a rush of nationalism in France. Enjoy...

11-02-2012, 11:29 PM
 29,879 posts, read 15,241,387 times Reputation: 15607
Quote:
 Originally Posted by harry chickpea Not another one. A pint is a pound, the world around.
Not really. A pint is a pound in the US. A Commonwealth pint is more like 1.25 pounds.

11-02-2012, 11:49 PM
 Location: Somewhere in northern Alabama 16,869 posts, read 51,398,709 times Reputation: 27761
Quote:
 Originally Posted by Dane_in_LA Not really. A pint is a pound in the US. A Commonwealth pint is more like 1.25 pounds.
Why do you think we won over the Brits?
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