Are time divisions of second, minute, hour arbitrary?

Answer 1

yes, some 2600 years ago, the babylonians worshiped seven "deities": sun, moon, mars, jupiter, mercury, venus, and saturn. these were the known planets at the time. the babyloians chose to divide the day into 24 equal time periods. they chose 24 because it is divisible by a lot of smaller numbers. they dedicated each hour to one deity in order of its speed across the sky. it happens that the first hour of each day is therefore dedicated to a different deity and that day was named for that deity. the first day of the week is sunday (sun day, if you wish). the second day is monday (moon day), if you know the names of the next few days in french or spanish then you will recognize that tuesday (mardi, martes) is named for mars, wednsday (jeudi, jueves) is named for jupiter, thursday (mercredi, miércoles) is named for mercury, and friday (vendredi, viernes) is named for venus. the last day of the week is saturday (saturn day). the babylonian counting system is based on sixty so they divided the hours into sixty minutes each and minutes into sixty seconds each.

Answer 2

The day (one rotation of the earth on its axis)and the year (one revolution of the earth around the Sun) are both defined by astronomical observation or the cycle of the seasons (in Egypt it was when the Nile flooded, determining when crops would grow on the banks of the river), Everything else is man-defined (though months do relate to the Moon and how long it takes to orbit the Earth once).

4,000 years ago, the Ancient Babylonians (Babylon is modern-day Iraq) with their sexagesimal (base-60) number system gave the world 360 degrees in a circle, 60 minutes in a degree and 60 seconds in a minute (and, perhaps suggested by a sundial being circular in shape, as is a clockface, that system was then applied to time as well as angles) and also 360 days in a year,

Which is 5 or 6 days wrong of course, and they had a system of 12 months, each of 30 days, with an additional month of 30 days added once every 5 or 6 years so the seasons and the calendar kept in synch with one another,

The 12 constellations of the zodiac (each being overhead for one twelfth of the night in turn) explain why the night was divided into 12 subdivisions called hours. The needs of seafarers to be able to navigate at night and get where they were planning to get to, led to this being an early, very practical invention as ancient civilisations developed sciences and measurement, It seemed logical to divide the daytime similarly, makng 24 hours in one sunset-to-sunset cycle,

The month as determined by the rotation of the moon (approx 28 days) about the earth and its phases would mean 13 months in a year, and that seemed at odds with 12 signs of the zodiac so they came up with the idea of the Moon being "in" one constellation for 30 days and then moving on to the next as being mathemctically neater than having 13 constellations for one purpose and 12 for another.

The year is the time the earth takes to go round the sun once and is measured observationally,

The second is now defined in the SI (standard international) metric system by the vibration period of a Caesium-133 atom as this can be defined precisely, whereas a fraction of a year cannot, given we add on leap seconds on June 30th or December 31st occasionally to keep everything in synch.

From 1793 to 1806 in the context of the introduction of a metric system of weights and measures, the French Revolutionary calendar decimalised time as follows

Ten days a week, 3 weeks a month and 12 months of 30 days plus 5 or 6 spare days added on,

10 hours a day, 100 mInutes in an hour and 100 seconds in a minute, Clocks were made to display time like this but it did not catch on and Napoleon scrapped the whole scheme in 1806,

It briefly resurfaced in the Paris Commune in 1871 and it was never heard of again,

Answer 3

Yes. The only time measurement that isn't arbitrary is the Plank second, which is the time it takes for a photon travelling at the speed of light to go the distance of a Plank length which is the smallest measureable distance using electromagnetic radiation techniques. Thus the Plank second is the smallest known possible unit of time at
5.39x10^-44 seconds

Answer 4

Sort of, yeah. The hour was invented by making 1/12 of the time between sunrise and sunset, and the same between sunset and sunrise. The importance of 12 has been attributed to the number of lunar cycles, if I remember correctly. The minute and the second, I'm not sure how they got 60.

Answer 5

Of course. The ancient Egyptians and Babylonian astrologers thought them up and we have been using them ever since.

If they lived on Mars, all the lengths of time that those units are composed of would be quite different.

;-D Just a sec, I am gonna have a cup of coffee. I will be back in a minute!

Answer 6

Yes, totally arbitrary. The ancients thought the numbers twelve, 60, and 360 were mystical so they designed our time system around these numbers. The words minute and second are short for the Latin: "pars minutum primum" and "pars minutum secundum", respectively. Pars, Partis is the Latin word for "part", and "minutum" is the Latin word for "small" or "little" and primum and secundum are the Latin words for "first" and "second" respectively. Thus "pars minutum primum" means "little part of the first kind" and "pars minutum secundum" means "little part of the second kind".

Answer 7

Good question. It took me a while to find the answer. I can not state it as well as it did in this article.

http://www.astro-tom.com/time/24_hours.htm