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Growing up in
the United States in the 1950s, I was used to such things
as inches, feet, yards; ounces (liquid and solid), pints,
pounds, etc. Then I entered my first physics class and
was bowled over by the metric system.
"My God, this is so much better! Why don't we use
this?" I exclaimed. After all; remembering that a
kilometer is 1,000 meters is so much easier than remember
that a mile is 5,280 feet and that a foot in turn is 12 inches.
Remembering that a kilogram is 1,000 grams is so much
easier than remembering that a pound is 16 solid ounces. Remembering
that a liter is 1,000 milliliters is so much easier
than remembering that a pint is 16 fluid ounces, that two
pints (32 ounces) is a quart, and four quarts (128 ounces)
is a gallon. The Celsius system also seemed much easier
than the Fahrenheit system. After all, water freezes at
0° C and boils at 100° C, which appeared considerably more
logical than water freezing at 32° F and boiling at 212° F.
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So
why did the United States, Great Britain, and a number
of other countries use these weird systems?
I got the answer the moment I stepped outside of the
physics classroom. Although I mathematically understood
metric units, I had no feel for them. If I went into
a restaurant, I knew exactly what I was getting if I
ordered an 8, 10 or 12 ounce steak. But if the menu
had shown a 230, 280 or 340 gram steak, I would have
been completely lost. Likewise, if I had to drive 60
miles, I understood that this meant about an hour on
the road. But if I had to drive 95 kilometers, I would
have had no idea of what this meant -- other than it
seemed to be considerably farther.
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Every change is one's basic
routine is difficult, even if it is clearly an improvement.
So it will still be some time before Liberia, Myanmar (Burma)
and the United States, the only three countries that have not
yet adopted the metric system, finally make the change. But
it does seem to be inevitable.
France adopted the metric system in 1799, one of the
consequences of the French Revolution. Japan made it official
in 1868 and Russia in 1917. Even Great Britain, which initially
spread inches, feet, miles, ounces, pounds, etc., around the
world, joined the club in 1965. Now that the world has gone
so massively metric (and the holdouts are likely to do so in
the foreseeable future), the question is: Why not complete the
job? The fact is, even metric countries still use a number of
old-fashioned, non-metric units that are largely irrational
and mathematically cumbersome.
For example, why is an hour 60 minutes, and a minute 60 seconds,
when an hour could be 100 minutes and a minute 100 seconds?
For that matter, why is a day 24 hours rather than 10 hours,
each hour made up of 100 minutes and each minute made up of
100 seconds? And why stop there? Why is the year made up of
12 months rather than 10?
If you think about it, the year used to be made up of ten
months until Julius Caesar (July) and Caesar Augustus (August)
stuck their vanity into it. Vestiges of the old ten-month calendar
can still be seen in the names of the last four months of the
year:
September (septum
= seven), October (octo = eight), November (novum = nine),
and December
(decem = ten). These should have been updated centuries ago.
Another apparently bizarre unit is the 360 degrees of a circle,
with each degree being divided into 60 minutes, and each minute
divided into 60 seconds. Couldn't the circle be 100 degrees,
divided into 100 minutes, divided into 100 seconds? Well,
yes it could.
Some mathematicians might argue that a system based on 60
has certain advantages for calculations over the metric system
based on 10. For specialty applications, they could retain
the 360 degree system, but there is no reason why the rest
of us should suffer with it. In fact, for certain applications
the 360 degree circle has been abandoned in favor of the two
radian circle, based on the formula for circumference C =
2 π r (circumference = two times pi times radius)..It
is possible to cite many other measures that could be decimalized.
However, we must be careful to make a distinction between
conventional measures and natural ones.
It is a convention to have 60 seconds in a minute, 60 minutes
in an hour, and 24 hours in a day. For whatever reason, we
chose these units. However, it is not a convention that the
year has 365 days because this is the time it takes the Earth
to orbit the sun. This is a natural unit dictated by nature.
It would make no sense to divide the year into 100 days just
to make calculations easier.
Such non-sense is not beyond human ignorance. At the end of
the 19th century, an American state came very close to passing
a law fixing pi at an even 3 in the belief that using it at
its true value (3. 3.14159265 . . .) was just too cumbersome!
When considering possible changes, we should be aware that
the definitions of fundamental units can change over time,
often due to developments in science. For example, since 1898
the kilogram, the basic unit of mass, has been defined in
terms of the of the international prototype kilogram (IPK).
This is a specifically constructed block of metal alloys maintained
under minutely specified environmental conditions at the International
Bureau of Weights and Measures in Sèvres, France. However,
since the IPK is subject to mass drift (changes in mass over
time), serious discussions are now going on to redefine the
kilogram in terms of a fixed number of carbon-12 atoms, silicon
atoms, or other fundamental, reproducible physical properties.
The fact is,
the IPK is the only SI unit (International System of Units)
still defined in terms of a carefully conserved reference
model. All others have been converted to physical properties
reproducible anywhere in the world. For example, the meter
used to be defined by a platinum-iridium rod. However, today
it is defined as 1/299,792,458 of the distance travelled by
light in 1 second (the "light-meter"), the denominator
of the fraction being the speed of light in a vacuum
So when will the circle, the clock, and the calendar go metric?
Probably not in the near future, but for psychological reasons
rather than scientific ones.
Although few people use the 360 degree circle in their daily
lives, this is how they learned (and suffered through) geometry
in school, so they would likely oppose changing it simply
because it would be inconvenient to do so. Also, certain aspects
of the 360 degree circle have become common currency in many
languages, where the equivalent of an "about-face"
is often described as a "180 degree turn".
Everyone uses the clock and the calendar constantly; they
are integral to the fabric of daily life. Any attempt to decimalize
them is almost certain to engender extremely stiff opposition.
For the vast majority of people, such a change would not be
just an inconvenience, but a major upheaval. For millennia,
the prospect of "squaring the circle" remained a
mathematical challenge. In 1882 it was shown to be impossible
because of the transcendental nature of pi. Making the circle
"less round" (going from 360 degrees to 100 degrees)
is not impossible, but chances are it will seem that way for
a very long time to come.
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