Days are split into 24 hours.  What is the basis of this?  Why isn't it split into e.g. 10 hours?  who was the first to use a time measurement approximately equal to our hour?
213133
The History of Analog Clocks (SEE FIRST LINK BELOW) provides an explanation of the origin of the 24-hour day. The system dates back 4,000 years, to ancient Egypt and Babylon. \n\nEgyptian astronomers divided the night hours into 12 distinct sets of star patterns, which emerged over the horizon at roughly hour-long intervals. They divided the day into 12 hours to match, and because they lived near the equator, the days and nights were of roughly equal length throughout the year. \n\nThroughout the rest of the world, the 12 "hours" of the day and night were flexible depending upon the season. It wasn't until the 13th century A.D. that an Arab scientist named Abul-Hassan suggested the idea of clearly defined hours. \n\nIt's also worth noting that the number 12 is special in many cultures. For example, Egyptians counted in base 12. Dividing the day into two sets of 12 was a simple and elegant way of condensing the annual calendar into a day. \n\n*Repost*
117537
1.  24 day\n2.   24*2/3=16\n3   24*1/2 12\n    (24+16+12)/3=17,3\n     17,3/3=5,7days
631191
No time does not exist. It is something people invented to try to "measure" duration of events. There is only life and it has a beginning point and ending point. Everything inbetween is just living.
88375
I dont know.  How did the english get the world to go along with it?  Also why not have 12 hours of light and 12 hours of dark.  Instead they do 6am is sunrise.  Why not 1am sunrise and 1pm sunset.
18253
day is roughly time taken by earth to complete one rotation,\nearths rotation is dependent on several factors like universal gravitational force and spin and orientation in space \nobviosly there are several seconds missing are added in this process\nso in general sence there could be seconds, minutes hours days years and even centuries added are missing to history\nas i said it is relative and dependent on a reference time if it exists
443
nothing to do with daylight savings. Daylight savings is a human invention, not a natural phenomenon.\n\n...because leap seconds are not being added to compensate for the Earth's rotation slowing down.\n\nThe amount of time it takes for the earth to revolve around the sun is 365.2425 days.\n\nEven that is an approximation, the decimal digits can keep going on.\n\nSo initially, the calendar was divided evenly in 365 days. But about every 4 years, you'd be off 1 day. A century later, you've drifted off by a whole month!\n\nSo, leap years came into effect. Febuary has another day every 4 years. \n\nBut now you've approximated a year to 365.25 days, when in reality, its 365.2425 days.\n\nEvery century, you'll be off 1 day.\n\nSo that's where the next rule comes into play: "If the year is divisible by 4, but not by 100, its a leap year."\n\nNow we've approximated it to 365.2425, but because its always going to be an approximation, our calendar days are always slipping. All because the earth doesn't take exactly 365 days to go around the sun.\n\nThis is why leap seconds are added, and not to account for the slowdown of the earth's rotation.\n\nAs to why days are divided in exactly 24 hours, I'm not sure. But I would think the time difference is WAY less than 20 minutes, or we'd notice that soon enough, its dark at noon! :)  Time was divided a long time ago, and a simple system was sought for keeping track of it, so the minuts/hour/year thing is a nice division thats easy to do math with. The lost time, if its accounted for by leap years and such, could be easier to manage.\n\nFirst, I never said the earth is not slowing down. I said its not why leap seconds exist. And ok, I can entertain my explanation may be wrong, but that's no reason for your condescending tone, Jolly Roger. But look, your link brings me to a christian science evanglism site, where is the evidence that my answer is incorrect? \n\nYou haven't bothered to explain his original question. If leapseconds account for the slowdown of the earth's rotation, why are there leap seconds and not leap milliseconds?\n\nIf you want to append to your answer, at least try to do so while respecting the other users on this site, and not insult their intelligence.\n\nThis has piqued my curiosity, if there's anyone out there that has a source that says my explanation is incorrect, I mean an actual science website, you know, one that steers clear of religion, please let me know.
118916
All Of You Are Idiots... How Do We Know that one Day=24 Hours??? Did They Wear Watches? Was One Year 365 Days?? Did They Have Calendars? For All We Know One Day In The Begining COuld Be Equal To 7 Days In What We Know ....Geesh Some People
500896
Actually a good many countries around the world use the 24 hour clock system. Then there isn't a need to say AM or PM, you know whether its day or night. Also the military begins attacks, movements and such on Greenwich mean time, its a town in Britain. And its used so everyone that aware of an operation knows what time it begins regardless of what part of the world they are in.
408606
Blame it on the Brits:\n\n"In 1792, the British East India Company established the Madras Observatory in Chennai (then Madras), largely due to the efforts of the British sailor-astronomer Michael Topping. In 1802, John Goldingham, nominated as the first official astronomer of the Company in India, established the longitude of Madras (13°5′24″N, 80°18′30″E) as 5 hours and 30 minutes ahead of Greenwich Mean Time as the local standard time. This marked the first-ever instance of the use of the current time zone, and departure from the earlier standard of day-beginning at sunrise getting shifted to midnight."\n\nIt is considered Indian Standard Time and the full explanation can be found here:\n\nhttp://en.wikipedia.org/wiki/Indian_Standard_Time\n\nThanks for a good search!!
413518
Latitude doesn't affect time at all. For Longitude, since 360 degrees encompasses the entire earth's surface, and since the earth rotates once in 24 hours, the time between two points one degree apart in longitude is 24/360 or 4/60 or 1/15 of an hour, which is 4 minutes. (you can break this down as far as you want, using smaller and smaller longitudinal differences). As an offshoot of this, there are 15 degrees in an arc of the earth representing  one time zone. By the way, there is no "local time" at either the North or South Pole, but that's a story for another time.
4021
well yeah... \nwell we dont have any definitive start or end point, so it's only relative to itself meaning that you can only measure a change in time, not how much of it you actually have. \nyour actual question is a little ambiguous, if this isnt what you meant, you can add some to the question,  are you looking for an explanation of how high velocities distort time or something, because I can explain that if you would like, just add it onto the question or make a new one or something.
243941
you didn't ask for the final number  so i will offer just the method.\n\n\n\n60 seconds in a minute X 60 minutes in an hour X 24 hours in a day = 86400 in day.\n\n86400 X 365 days = 31536000 seconds in a non leap year\n86400 X 366 days = 31622400 seconds in a LEAP year\n\nin one billion years there are 250 million leap years and 750 million non leap years.\nTHEREFORE:\n\nTotal # of seconds =\n(31622400 X 250,000,000) + (31536000 X 750,000,000)\n\nadd em up.  my calc won't go that high and my pencil lead broke.  :)\n\nOK OK! I'll tell ya.\n\n8,142,120,000,000,000,000 seconds
40325
In the army we always started our logs @ 0000 and closed them out at 2400. so i'm not sure where your getting your info. the time 24:00:00 does, after all, only exist for one second and then becomes 00:00:01
524515
Instead of using 2 sets of 12 hour time periods, \nyou use 1 set of a 24 hour time period, therefore,\nafter 12 noon the time goes as follows:\n1 is 13:00 hours\n2 is 14:00 hours \n3 is 15:00 hours\n4 is 16:00 hours\n5 is 17:00 hours\n6 is 18:00 hours\n7 is 19:00 hours\n8 is 20:00 hours\n9 is 21:00 hours\n10 is 22:00 hours\n11 is 23:00 hours\n12 is 24:00 hours\n\nJust remember to add the 12 to any hour after noon and you will know what time it is in military time
300784
The Earth turns one time around in 24 hours and as it does the whole sky seems to turn around the North star. Of course the sky is really not moving at all. The Earth under our feet is turning, but it really does LOOK like the sky is turning! The North star never rises or sets because it is right above Earth's north pole, so as the Earth turns it just stays there in one spot while the whole sky seems to turn around it. Stars close enough to the north star can go around without ever rising or setting. So the sky looks like a big clock, but a 24 hour clock. You may have seen special military clocks that have 24 numbered hours and the hour hand goes once around in a day. It is kind of silly anyway having 12 hours on the clock and making the hour hand go around twice a day. Who made that up?\n\nAnyway, you can use the stars in the sky as your dial and the north star as the center of that dial. Only the dial turns and the hands stay still. Oops, we have no hands! We will just imagine a hand always pointing up and let the dial turn behind it. And there are not really numbers, you have to draw a picture of the stars and write numbers on it so you can compare the sky to it and tell time.\n\nClick the link below for instructions.
328143
The Bible speaks of 6 creative days.  It does not say that the days lasted 24 hours.  A day can indicate a period of time (in Noah's day, for example).  The Bible also says that a 1000 years is a day to God.  On the seventh day he rested from his creative works.  We are still in the seventh day of rest.  (we see this seventh day is longer than 24 hours, and longer than a 1000 years)  Scientific evidence supports that the earth is 4 billion years old.
30290
There are even today many different ways of figuring out time. For example this weekend, on 29th Jan the chinese new year starts. It is Year 4703 by the Chinese calendar. And it is the jewish year 5677.\nAnd even the christian calendar has been modified a couple of times. The gregorian calendar reform was adopted in 1582 but not in England and so also not in the US, they only changed in 1752 (so they lost 11 days).\nWhich year we are in is only relative to what you want to measure. If you want to be more explicit you don't just say B.C. (Before christ) but B.C.E (before the christian era). As long as you can figure out how far apart they are you can easily convert one into the other and allow for changes. \nFor time of the year (month/day) it is probably best to go by a system like now, which is constant with and corresponds to the seasons of the year. So while George Washington was born on the 22nd feb 1732, his parents must have thought it was the 11th when he was born. \nI don't know how far historic dates get modernized to reflect calendar changes.