PDA

View Full Version : Time Measurement

§rv
2005-Oct-23, 12:58 AM
How did time come to be measured in the way it is today? : 60 seconds make a minute; 60 minutes make an hour etc. I mean, isn't that rather like the old (now american) nonsensical system of measurement of feet, yards etc? Why haven't there been any pressures to change this old system to something more metric? (I know there was a thread a while back on new concepts of measuring time). Are there any current proposals for changing this system?

Matthew
2005-Oct-23, 01:35 AM
The hours and minutes are base-60 which came from the Babylonians. This base-60 system is also used in degrees (the measure of the angle). 60 seconds to a minute, 60 minutes to a degree. For more on base-60 see Wikipeidia's article on base-60. (http://en.wikipedia.org/wiki/Base_60)

Are there any current proposals for changing this system?

There probably has, but I don't see any coming true in the foreseeable future. In science where exact measurements of time are necessary everything is measured off the second (an SI-unit). There is limited use of minute and years (since the length of a year is changing, is it a leap year or not? the length of a year is 365.25 days, but in a non leap year should you measure using .25 or not?).

In the general populace there is no reason to change. It works and works well. The hour is a very convenient unit, just the right length. Would you like to say, the game is in 3.6 kiloseconds? I don't. The only other reason for going to the decimal time system is for computing. But any computer programmer worth his/her salt can work with minutes, hours, weeks, years. Leap years occur regularly. Its not like the computer has to access a central server to find out when the nextleap year is.

Gillianren
2005-Oct-23, 07:18 AM
The French tried metric time, just after the revolution. It didn't go over so well, especially since people on the metric week got two days off as before--but they worked three more days a week between those days off.

Eroica
2005-Oct-23, 03:13 PM
Decimal Time (http://en.wikipedia.org/wiki/Decimal_time)

genebujold
2005-Oct-23, 04:15 PM
The hours and minutes are base-60 which came from the Babylonians. This base-60 system is also used in degrees (the measure of the angle). 60 seconds to a minute, 60 minutes to a degree. For more on base-60 see Wikipeidia's article on base-60. (http://en.wikipedia.org/wiki/Base_60)

There probably has, but I don't see any coming true in the foreseeable future. In science where exact measurements of time are necessary everything is measured off the second (an SI-unit). There is limited use of minute and years (since the length of a year is changing, is it a leap year or not? the length of a year is 365.25 days, but in a non leap year should you measure using .25 or not?).

In the general populace there is no reason to change. It works and works well. The hour is a very convenient unit, just the right length. Would you like to say, the game is in 3.6 kiloseconds? I don't. The only other reason for going to the decimal time system is for computing. But any computer programmer worth his/her salt can work with minutes, hours, weeks, years. Leap years occur regularly. Its not like the computer has to access a central server to find out when the nextleap year is.

Wow - excellent treatise, Matthew - really! I commend you!

The metric system is somewhat of an anomaly. It's derived from the physical properties of the Earth itself, namely, 360 degrees to make a circle, 24 hours in a day (2x12, 12 being a number of significant note in the days of old), and 60 seconds / 60 minutes as being convenient demarcations of time itself.

Length continues to be described in metric terms (m), but time has been included into metric terms as is, without any consideration for variations thereof.

To point, the Earth's spin is slowing due to tidal forces. Does that mean we need to change the fundamental nature of the second, simply because 1 day no longer equals 86,400 seconds? By no means!

To be perfectly honest, we should have two time classifications. The first of which should indeed be tied to our planet's rotation, but the second should be tied to a standard which will survive our planet's slowing spin. Thus, I do propose a metric time standard, one based off easily measured vibrations found in nature, such as the Cesium atom.

Fortunately, this has already happened, way back in 1967: "The 13th General Conference on Weights and Measures defines the second on the basis of vibrations of the cesium atom; the world’s timekeeping system no longer has an astronomical basis."

Source: http://tf.nist.gov/timefreq/cesium/atomichistory.htm

The current accuracy of atomic clocks is on the order of one second in 60 million years, which means that this is no longer a subject about which any of us need give any further consideration!

Source: http://tf.nist.gov/timefreq/cesium/fountain.htm

Nevertheless, I, for one, would welcome a metric time system, one where the Earth had ten hours between noon to noon, and 100 minutes per hour.

Given 60 minutes per 24 hours, for a total of 1,440 minutes a day, the metric clock's answer of 1,000 minutes per day isn't far off.

I would think that people would quickly become accustomed to a metric clock, particularly given the fact that most people converted to the metric system without fuss over the last century.

Why the US has such difficulty, I'll never understand!

hhEb09'1
2005-Oct-23, 05:18 PM
Given 60 minutes per 24 hours, for a total of 1,440 minutes a day, the metric clock's answer of 1,000 minutes per day isn't far off.

I would think that people would quickly become accustomed to a metric clock!It'd be closer yet if we went with 100,000 seconds per day. Right now, there are 86,400 seconds in a standard day, more or less. A kilosecond would then be about fifteen minutes (14 2/5 min.)--just about right for partitioning our TV schedules.

swansont
2005-Oct-30, 12:14 PM
The current accuracy of atomic clocks is on the order of one second in 60 million years, which means that this is no longer a subject about which any of us need give any further consideration!

Source: http://tf.nist.gov/timefreq/cesium/fountain.htm

Ahem. Most of us don't need to give it further consideration. Some of us do (http://tycho.usno.navy.mil/clockdev/)

Oh, and <obligatory grumble> NIST's fountain is a frequency standard, not a clock.

GDwarf
2005-Oct-30, 12:52 PM
I actually thought about metric time for a while, but the biggest problem you have is that a year must be 365.25 days, unless you want days to not coincide with the light/dark cycle, which is needlessly annoying. Also, in times measured in under a second it is a metric system, metric naming conventions, and units all dividable by ten.

One of the reasons that the metric system took so long to catch on was because the imperial one is convenient, for some reason most things you need to measure will turn out much nicer when printed in imperial then in metric. The reason the imperial system did (mostly) die out was because it was hard to do complex calculations with it when you had to change units, it could be done, but it took longer then simply using metric and multiplying or dividing by ten.

However, our current way of measuring time > a second is also rather easy to do math with, you can divide 60 many more ways then you can divide 10 (and not get a decimal number). For conversions it's still a pain, but as it fits the way the Earth currently works, there is very little reason to change it. Now, should the Earth stop spinning a metric system would probably be adopted, as there is very little reason to use a system that is difficult to do math with and that doesn't conform to how things are.