|
|
|
Measurement Systems
By
Peter Glen
We have a great many
numbers and measuring systems around us. Most of it we take for
granted. But if we think about it,
why 24 hours a day? Why seven days a week? Why 360 degrees to the
circle? Read on for the answers.
The 360 degrees to a circle was a hard one to get used to.
Being raised with the ten based common numbering system, the 360 just
stood
out like a sore thumb. But the reason is very simple. One year is 365
days.
The earth rotates a whole circle in that period of time. Which means
the
earth progresses on its orbit around the sun one degree a day.
The
stars are offset by one degree every night. While we cannot easily
perceive
this, putting a solid marker in the ground and observing the relation
of
the stars relative to that is very distinct. One degree.
A natural question arises. Why not 365 degrees to the
circle. Again, the simplest answer is sought for. It is so much easier
to work with 360 then 365. The former is divisible by a great many more
common factors then latter. And making that rounding introduces a very
small error. 365/360 which amounts to 1.38% deviation.
The 24 hour day. This is such an ancient assignment, that
we can only speculate. Looking around in nature, finding something that
has a predictable hour of cycle time was not easy. Especially,
something that reproduces itself on a global scale. We know, the
ancients where following nature accurately, they based every other
measuring system on nature's display.
I started to observe the tides on the ocean. And it hit
me. The tide is shifting every day by one hour. The rest of the thought
process is easy. The ancients marked their timing to reflect one unit
as the timing shift of the tides. We know, that the tides take 28 days
to repeat, so the tide shifted in 1/28 of a day. Again, simplicity
suggested to pick the number close to it with the most number of prime
numbers. This is 24. The hypothetical error margin: 16%
The seven day week. Textbook claims that the egyptians
where the one who established it as a unit of measuring a week. While
building the pyramids, they observed the biorhythm of the workers.
Assumed that they are most productive when they have a resting day
every seven days. It goes contrary to our five day work week. This
assumption is too dependent on the human factor. As we observe on every
other measuring system, it always observes the nature factor.
We still theorize about the seven day week. Maybe the 28 day
moon phase, partitioned into four quarters is the answer to the 7 days.
Maybe the
future will hold some unexpected answers.
The thirty (and a half) day month. The moon makes approximately
13 orbital cycles in a year. Again, this is a number that is not
readily divisible by many factors. So we partitioned the year into 12
cycles. This results in a 30.4 days per unit. This is why our months
range between 30 and 31 days. The leap month is the exception. The
earth does not rotate around exactly in sync with its orbit around the
sun. It rotates 365 1/4 times. The 1/4 times adds to a whole day after
four years, hence we add a day to our leap month. (february) Why
do we bother to correct this 1/4 offset? Many measurements of ours
depends on time. The shortest day of the year the longest day of
the year are expected to fall on certain dates. Our corrections make
sure it happens the way we expect it.
E-White Paper (C) 2002, by Peter Glen,
Listed in the International
Who's Who of Information Technology.
|
|
