Thread: Why are there 24 hours in a day?

Anybody knows why the day has 24 hours, each hour has 60 mins. and so on?

I read that it was because the Sumerians used a base 12 system, and the Babylonians adopted this and added their base 60 system. That actually sounds a little uncertain, so i'd like to know if any of you guys knows the truth .

Because the number 24 is factorable in a wide variety of ways.

The ability to easily break the number 24 into fractional time when doing calculations without an abacus or writing tools, and without the number zero, is a very useful property.

Originally Posted by Cuete

Anybody knows why the day has 24 hours, each hour has 60 mins. and so on?

I read that it was because the Sumerians used a base 12 system, and the Babylonians adopted this and added their base 60 system. That actually sounds a little uncertain, so i'd like to know if any of you guys knows the truth .

When I had read only your question I was going to inform you of the base 60 system of numbers that the babylonians had. I found this out reading up on the history of mathematics. I hadn't heard of the base 12 system used by the Sumerians.

does a day consist of 24 hours or 23:56 hours

veli

does a day consist of 24 hours or 23:56 hours

That's right veli, but the question is why arbitrarily choose 24:60:60 and not 30 or 16... or 10...

Possibly because the Earth revolves 360 degrees in a 24 hour period...

360/24 = 15 degrees per/hour.
360/24/60 = 0.25 degrees per/minute.

Very useful in Astronomy. Quite a basic fact.

Of course, it's less clear when you use the 365.25 days per/year. But that wasn't even factored in until the (IIRC) Julian calendar (and then refined in the Gregorian). Likely the 24-hour standard had been used for hundreds and even thousands of years prior to those.

You're right about the Julian calendar, Yev. In fact, the Roman calendar had gotten SO far off of actual time that by the mid-first-century BCE, January 1 had crept into autumn.
However, it appears that the Antikythera machine (built about 35 years before Caesar took power) actually had a slip-disc in it that allowed for 365.25 days/year. So, it appears that was known before Caesar put it into the Roman calendar.

JM

Originally Posted by Yevaud

Possibly because the Earth revolves 360 degrees in a 24 hour period...

360/24 = 15 degrees per/hour.
360/24/60 = 0.25 degrees per/minute.

Very useful in Astronomy. Quite a basic fact.

Again, like you illustrated, some numbers divide very easily in your head and so these became the standard units in daily common use for the pre-metric days:
8 (ounces in a cup, bits)
12 (inches, half-days)
16 (ounces in a pound)
24 (hours, carats)
60 (minutes,seconds)
360 degrees

Personally, I always found it astounding that we built such a technological society in the Western world - using pounds, feet, yards, miles, what have you.

4... 8... 12... 24.. 60.....

It's the conspiracy of the 4N subset!!!!!!!!!!!

JM

(old joke here)

For I=0 to 10^999999

Print "Arrrrggggghhhhhh!!!!! Curse you, Buckaroo Banzai!"

Next I

End

Originally Posted by Yevaud

Personally, I always found it astounding that we built such a technological society in the Western world - using pounds, feet, yards, miles, what have you.

That's because we built a technological society before we had calculators or sliderules or even the abacus. Frankly, without these tools, calculations involving fractions were easier within the 4N subset than they were using alternatives such as metric systems. This is particularly true before zero became commonly adopted.

Originally Posted by Yevaud

Possibly because the Earth revolves 360 degrees in a 24 hour period...

acually about 23:50 hours but the calender is rounded.

chamilton, if you are going to post in just about every thread ever created on the forum would you be good enough to get your facts right.

The average day length is not 23.5 hours. If it were, then sunrise ould be half an hour earlier every day. The average length is 23 hours 56 minutes 4.091 seconds.

A discussion of variations around that average may be found here.
http://geology.about.com/library/weekly/aa090797.htm

Originally Posted by Ophiolite

chamilton, if you are going to post in just about every thread ever created on the forum would you be good enough to get your facts right.

The average day length is not 23.5 hours. If it were, then sunrise ould be half an hour earlier every day. The average length is 23 hours 56 minutes 4.091 seconds.

A discussion of variations around that average may be found here.
http://geology.about.com/library/weekly/aa090797.htm

meant the decimal to be colin. my bad. ill edit it.

LOL!

You should really take the time to read other peoples posts before posting. He wasn't even talking about the decimal, he is saying that there can not be 23.5 hours in a day... just reread his post carefully...

umm, he was talking about my fact. it looked like 23 and a half hours and i meant ABOUT 23 hours 50 minutes. i never said it was exact.

You originally stated 23.5
I accept that you meant 23:50 i.e. 23 hours fifty minutes
However you corrected this to 23:5
I do not know what time 23:5 represents
It is certainly not 23 hours 50 minutes
It is closest to representing 23 hours 5 minutes, but that would be 23:05

Nowhere in your original post do I see the word 'about'.

This must seem like nitpicking to you. Wrong. It is about accuracy and precision. Both are cornerstones of scientific methodology.

Ignorance is something we all possess in such abundance that there is little difference between a Nobel prizewinner and Joe Bloggs. The distinction between the two arises in how they deal with what they do know and what lies on the frontiers of their knowledge. In other words, their is a difference between errors committed through ignorance and those committed through sloppiness.

my original post did indeed have the word 'about'. changed to 23:50.

Originally Posted by Cuete

Anybody knows why the day has 24 hours, each hour has 60 mins. and so on?

I read that it was because the Sumerians used a base 12 system, and the Babylonians adopted this and added their base 60 system. That actually sounds a little uncertain, so i'd like to know if any of you guys knows the truth .

The sixties come from Babylon. The seven days in a week come from Hebrew culture. You decide whether you believe that the Ten Commandments written by the hand of God on tablets of stone gave us seven days in a week, or that it happened because there are four sevens in twenty-eight (the number of days in a lunar month, and the rough duration of a menstrual cycle) and that "27 days shalt thou labour, but the 28th is sabbath of the Lord Thy God" is a bit harsh. The two lots of twelve hours you asked about, approximate day and night durations near the equator, probably come from the fact that plenty of ancient cultures recognised twelve has plenty of factors, making it easier to design patterns of shift working.

John

Better question is why do some months have differnt days then others. What women is this based on ?

babylons said that one second is the rate wich a normal human heart beats when you lie down and is completly relaxed and have been it for a while, a minute is 60 secondsd, according to their calculating system it wre 100, they decieded a hour is 60 minutes (100 for them) then when they looked on the day they saw it took exacly(they couldnt measure good enough to detect the little differens of 3,5 minutes) 24 hours and it fitted them good

Originally Posted by John Allman

[
The sixties come from Babylon. The seven days in a week come from Hebrew culture. You decide whether you believe that the Ten Commandments written by the hand of God on tablets of stone gave us seven days in a week, or that it happened because there are four sevens in twenty-eight (the number of days in a lunar month,

The lunar month is 29.5 days long, not 28. The week and the month are only slightly related.