Talk:Second

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[edit] sources

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This page contains text taken from the public domain article at http://tycho.usno.navy.mil/leapsec.html


Gentlemen, Interesting article, will be useful to include a historical note about why exist 60 seconds in a minute? Milton 22:03, 28 Jan 2004 (UTC)

Now, I'm pretty sure a second is actually defined as the time it takes light to travel a specific fraction of a meter in a vacuum, I'll google and add it Thunderbolt16 22:17, Mar 20, 2004 (UTC)

No. However, a metre is defined as the length that light travels in a specific fraction of a second. Morwen 22:19, Mar 20, 2004 (UTC)
Thanks, I misremembered. Thunderbolt16

[edit] Ambiguous definition of ground state

The article twice defines the ground state of the cesium atom. First, as the state when there is zero magnetic flux, and then as the state when there is zero magnetic field. I don't think these two statements are equivalent, and I'm curious if anyone knows which definition is more correct? --ABQCat 00:31, 30 Aug 2004 (UTC)

Magnetic flux is not applicable here, whereas magnetic field is. Magnetic flux is the total magnetic field passing through some area measured in webers, thus is a distributed quantity, whereas a magnetic field is applicable to a point, like an atom. We need not be concerned with the distinction between B and H (both point quantities) because it only exists in the metric system, or rationalized mks units. In CGS electromagnetic units they are one and the same, because permeability is the dimensionless unit 1. However, zero magnetic field need not be stated twice in the article. — Joe Kress 16:10, Aug 31, 2004 (UTC)
Thank you - I just didn't have sufficient technical knowledge to be able to correct the ambiguity. I agree with you that we don't need double definition of the second. The article is a good candidate for cleanup by the community - it's messy and seems redundant towards the end. Unless I'm missing something, I think the article could be re-written as much more concise and clear. --ABQCat 16:44, 31 Aug 2004 (UTC)

[edit] January 0

What does January 0 mean in this article?? Georgia guy 02:38, 27 Feb 2005 (UTC)

1900 January 0 = 1899 December 31. Furthermore, the rest of the definition has a specific astronomical meaning which is not obvious. I'll revise the subsequent paragraph. — Joe Kress 03:31, Feb 27, 2005 (UTC)

[edit] Not derived units?

Interesting... SI uses the term 'derived units', but apparently some other field does not? Which would then be the preferred term? See also SI derived units. Radiant_* 12:58, May 26, 2005 (UTC)

What are you talking about? In metrology jargon, a "derived unit" is a unit to measure some other quantity than the quantity measured by the "base units", and the "derived unit" is built up from some combination of those "base units". For example, in SI the SI derived unit of the quantity force is the newton, which is built up from the base units for the quantities mass, length, and time as 1 kg·m/s².
The units formed by adding prefixes to the root word (note that this is not to the base unit, as we can see in the case of centimeters in cgs systems and kilograms in mks systems including SI) is something entirely different. Though they may be in some senses of the word "derived", they are not "derived units"—a term with more specific meaning in metrology jargon. Gene Nygaard 13:21, 26 May 2005 (UTC)
  • Okay, thanks for the explanation. Radiant_* 13:24, May 26, 2005 (UTC)

[edit] Multiples and submultiples section

Is this really appropriate? This is just some info on metric prefixes. Notthe9 07:29, 13 August 2005 (UTC)

[edit] Hundredth of a second

Is there a word for a hundredth of a second? --Revolución (talk) 23:29, 13 August 2005 (UTC)

Combine centi- (1/100) and second: centisecond or cs. — Joe Kress 02:19, August 14, 2005 (UTC)

Can we add this information as well as re-add the information about other ___seconds. Such as was: http://en.wikipedia.org/w/index.php?title=Second&diff=14261799&oldid=14261381? Hyacinth 09:59, 14 December 2005 (UTC)

Just because it can be formed doesn't mean that is either is used or should be used. Centimeters are okay for your hat size, and cubic centimeters for volume. That's about the extent of the usefulness of any prefixes which are not powers of 1000. We don't need to encourage use of centiseconds, nor any other new use of any of the prefixes centi-, deci-, deka- (even if you spell it deca-), or hecto-. Gene Nygaard 12:54, 14 December 2005 (UTC)
What about nanosecond? Hyacinth 12:54, 14 December 2005 (UTC)
Use milliseconds (ms) instead of cs 82.94.1.175 10:42, 2 March 2006 (UTC)

[edit] Abbreviations for 'second'

I was wondering if there was the need for a short passage on the abbreviations for second (i.e. s, sec, ") because articles from these pages link to here. GoldenTie 10:53, Christmas Eve 2005 (GMT)

Wikipedia policy is to place redirects to a specific page in bold so that anyone who follows such a link knows that s/he has arrived at the main page. Thus I've put the symbol s in bold and added the informal abbreviation sec. " redirects to arcsecond, not to second. — Joe Kress 04:10, 26 December 2005 (UTC)

[edit] Neglected 2nd meaning

The article currently neglects a second meaning of second: The period of time (i.e., the set of all instants) between two fixed instants of time, being fixed by UTC. For example, "the first second of a day" refers to the period of time beginning at a certain instant (the beginning of a day) and lasting 1s (duration). Johannes Simon 2006-02-25 14:10 (UTC)

[edit] Is it True and Is it Possible???/

The article says This definition refers to a caesium atom at rest at a temperature of 0 K As far as I know attaining this temperature is impossible,But can someone quote a source that this was indeed adopted as req. for standard def. of second.Holywarrior 12:28, 3 July 2006 (UTC)

It is part of the official BIPM definition of the second. All caesium clocks operate at room temperature. Measurements confirmed that the duration of the second varied depending on the ambient temperature surrounding the physical atomic clock. This sentence requires the duration of the second to be corrected, as if the clock was in an ambient temperature of 0 K. — Joe Kress 06:36, 4 July 2006 (UTC)

[edit] multiples

Please don't remove multiples, for consistency they are in all seven base SI units.


[edit] Table Needed

Much like other standard units of measurement, I believe a table for milliseconds, microseconds, nanoseconds etc. would be a useful addition. Of all the info on wikipedia, I was a little surprised to see no entry for nanosecond. Milliamp

[edit] Trivia

Removed the bit on pi*1E7 being within 0.5% of the number of seconds in a Julian year. Pi isn't related to the length of the year and it's just a coincidence. pi*10 is approximately equal to the length of the month of January. Shall we have that too?


[edit] Relativity

I'm by no means an expert in this area, so I may be missing something obvious. The definition of a second seems to be ignoring issues regarding relativity as discussed in the GPS article. As noted there, a cesium clock in orbit will exhibit different behavior than one on the ground. Which is considered "correct" by the standard? The article makes mention of a cesium atom at rest, but at rest compared to what? —Preceding unsigned comment added by 71.146.43.85 (talk)

The article is indeed missing a crucial definition. The SI second has been defined on the rotating geoid (mean sea level) since the beginning of 1977. This was more precisely defined in 2000. The exact wording of this in the article remains to be determined. — Joe Kress 23:59, 9 August 2007 (UTC)

[edit] History

The history section describes how certain ancients are known to have divided up the day but surely why they divided up the day way must be a matter of pure speculation. The section kind of implies that the ancients took a day and subdivided it and the result of that subdivision was the second. I suspect that it is coming to the concept from competely the wrong direction.

The thing I would say about the time division we commonly refer to as a second is that it is about the time to say a normal word at normal speed as in counting. In other words the time between one word and the second word is one second. As all humans can relate to speaking I would conject that the humans would have had the concept of a second long before anyone decided how many seconds there were in an average day and then devised the system for counting subdivisions of days into hours and minutes and seconds.

Etymologically speaking the word second comes from Old French but I am not sure if the word had both meanings in Old French as it still has in English. Deuxième is I think modern word for the ordinal whereas second is the time interval.--Tom (talk) 14:02, 26 January 2008 (UTC)

The second as we know it began during the Middle Ages and is simply the result of subdividing the hour sexagesimally. Previously, only the day had been subdivided sexagesimally. Your counting speed hypothesis would be prohibited original research, unless you can verify it in some published form. I doubt that any author has concluded that. The speed of counting is related to the speed that syllables, not words, are spoken. Small numbers usually have one syllable whereas large numbers are polysyllabic, so the speed they are spoken varies considerably. Monosyllabic counting words are spoken much faster than one per second. — Joe Kress (talk) 08:36, 27 January 2008 (UTC)
The issue I make is just a reasonable hypothesis. I don't have a reference but I am sure I am not the first one to have thought about the issue. The point is that I think it highly unlikely that the start point was a higher frame of reference, e.g. a day which was divided arbitrarily into 24th and 60ths twice to arrive at a set time span the second. Why 60ths? I doubt very much that the concept of this short and humanly meangingful time span came into existence in the Middle Ages! It is age old. The second is an easy to reference for humans to reckon with, as are days and months. Whether its the time to say a word or the time to take one pace forward. Intermediate times are not. It is therefore much more likey that the divisors were created break the relatively high number of seconds in a day into meaningful chunks such as minutes and hours. Human scales for measuring things are perfectly normal such as the use of "hands" and "feet" in measuring lengths. In Finnish the word for "inch" is "tumma" (thumb) i.e. approximately the width of a man's thumb.--Tom (talk) 11:11, 27 January 2008 (UTC)
The smallest Babylonian unit of time was the barleycorn, 3⅓ seconds, hence much larger than our second. Even though the Babylonians originated the sexagesimal system some 5000 years ago, the barleycorn was not related sexagesimally to any other unit, so it developed independently. Whether or not it was related to a human measure I do not know, but the barleycorn was not the ancestor of our second. Consider the Hindu units of time mentioned in the second millennium BC vedas. They used ratios much smaller than 60. The human measure nearest in size to the second was the nimesha or blink which was about half a second. But the nimesha is not the ancestor of our second. — Joe Kress (talk) 07:05, 28 January 2008 (UTC)

What cannot be ignored here is the divisions of a degree. Far more practical than minutes & seconds of time would have been minutes & seconds of arc. I have seen articles that assert that temporal units were derived from the geometric/geographical/astronomical ones --JimWae (talk) 07:11, 28 January 2008 (UTC)