AndyDufresne wrote:I'll speak the the 24 hour day bit. I recall that a number of our precursor ancient civilizations were fond of counting things in base 12, instead of say in base 10. Now everyone in our modern era is left with a bit of a mish-mash of various counting methods jammed together, examples:
Base 6 (60 Seconds in a minute, etc)
Base 10 (So many things)
Base 12 (24 hours a day)
But mathematics and numbers have ever been a strong suit of mine, I just recall this from some history reading I think.
Edit: I turned to my trusty friend, Scientific American, and just located this article from a number of years ago. A fun read to give you some history and insight:
Why is a minute divided into 60 seconds, an hour into 60 minutes, yet there are only 24 hours in a day?--Andy
Interesting. A few thoughts:
(1) My question is more to do with why do we still use these things and not something else and not so much where they came from, but being the ex-history major that I am... er was... it is interesting.
(2) Egyptians are weird - Why would they use the knuckles of fingers intead of the fingers themselves?
This division reflected Egypt's use of the duodecimal system--the importance of the number 12 is typically attributed either to the fact that it equals the number of lunar cycles in a year or the number of finger joints on each hand (three in each of the four fingers, excluding the thumb), making it possible to count to 12 with the thumb.
(3) f*ck yeah Greeks!
The concept of fixed-length hours, however, did not originate until the Hellenistic period, when Greek astronomers began using such a system for their theoretical calculations. Hipparchus, whose work primarily took place between 147 and 127 B.C., proposed dividing the day into 24 equinoctial hours, based on the 12 hours of daylight and 12 hours of darkness observed on equinox days.
(4) See... this makes sense to me -
Despite this suggestion, laypeople continued to use seasonally varying hours for many centuries. (Hours of fixed length became commonplace only after mechanical clocks first appeared in Europe during the 14th century.)
(5) Culture beats science again!
This changed in 1967, when the second was redefined as the duration of 9,192,631,770 energy transitions of the cesium atom. This recharacterization ushered in the era of atomic timekeeping and Coordinated Universal Time (UTC). Interestingly, in order to keep atomic time in agreement with astronomical time, leap seconds occasionally must be added to UTC. Thus, not all minutes contain 60 seconds. A few rare minutes, occurring at a rate of about eight per decade, actually contain 61.
Posted: Mon Feb 04, 2013 1:37 pm
