Talk:Leap second/Archive 2

Archive 1

Archive 2

Screenshot

I like the screenshot (got one myself). I like that it's actually a UTC time, compared to the previous Central Time image (and my new Pacific Time image). However, it's odd that it reads "Right now, the official U.S. time is". I know why it does, but perhaps crop that image to exclude that line. (On the other hand, the source is from NIST in the U.S., so I suppose it could be considered the "official U.S. UTC time".) goodeye (talk) 01:28, 1 July 2012 (UTC)

Negative leap seconds

The article should mention that leap seconds can be either added or removed. The article currently gives the impression that they can only be added. Thue (talk) 19:34, 4 July 2012 (UTC)

The article states "A negative leap second would suppress second 23:59:59 of the last day of a chosen month, so that second 23:59:58 of that date would be followed immediately by second 00:00:00 of the following date. However, since the UTC standard was established, negative leap seconds have never been needed." Jc3s5h (talk) 20:26, 4 July 2012 (UTC)

It would probably help to insert explicit references to ITU-R TF.460 both here and on the UTC page. The ITU-R made the recent versions of this defining document openly available starting in December 2010.Steven L Allen (talk) 02:00, 12 July 2012 (UTC)

Although recent versions are useful for current practice, they are useless as historical documents. Only the 1970 and 1974 versions of CCIR Recommendation 460, or a reprint of them, or of their leap second sections would serve that purpose. — Joe Kress (talk) 08:36, 12 July 2012 (UTC)

US NBS reprinted the 1970 original Rec. 460 on page 31 of Monograph 140, Time and frequency: theory and fundamentals (Byron E. Blair, 1974). Prior to that it also reprints numerous other original defining documents about the SI second and TAI.Steven L Allen (talk) 18:31, 12 July 2012 (UTC)

Why can't the abolition movement just change to using TAI?

I am curious why the article makes no mention of the idea that those who wish to abolish the leap second might do better simply to use the existing TAI time system for their purposes rather than altering UTC to make it resemble TAI. We've had TAI since the 1950s, and it does what those who seek to abolish the leap second want a timescale to do. Why don't they just switch from using UTC to using TAI? If there are any interesting reasons why they would rather alter UTC than switch to using the existing TAI system, those reasons ought to be discussed in this article.

I'd edit the article to discuss these reasons myself, if I knew of any. But if there are no good reasons, that point ought to be addressed in the article as well, and I'm not enough of an expert in this subject to make assertions about the absence of good reasons.

In particular it's kind of crazy that we already have GPS time, which is a variant of TAI that differs from it by a constant offset. Abolishing the leap second would just leave us with a third such constant-offset-differing timescale when TAI is already adequate for all such purposes. Reasons for wanting to multiply the number of constant-offset atomic timescales should be discussed in this article, if such reasons exist.

--arkuat (talk) 23:41, 26 July 2012 (UTC)

Only arguments that have been reported in reliable noteworthy sources should go in the article. But I suspect the reason many of these sources have not adopted TAI is that it is not the legal civil time anywhere in the world. Many systems must keep legal time, and many other systems must interface with systems that are keeping legal time. Jc3s5h (talk) 03:08, 27 July 2012 (UTC)

What is "legal time"? -- Q Chris (talk) 07:23, 27 July 2012 (UTC)

In any country, civil time (rather than "legal time") is the timescale approved for official and commercial use.

In Switzerland for example civil time is defined as UTC+1 (+2 in the summer). So that's what you are required to use, by law, whether in a contract, a bus schedule, a police report or whatever. In the same way that you are required to sell, say, gasoline by the liter.

In practice the civil time of most (all?) countries is based on UTC. So for any system that interact with the outside world using anything else than UTC is not an option. Thus if you are not happy with UTC you can't just use something else, you need the whole word to switch.

TAI couldn't be used directly as we don't want clocks to suddenly jump backwards. Continuity with the current time has to be maintained. Whether you formally introduce a new timescale or change the definition of UTC is a detail.

So the real question, which IMO is not really addressed in the article at this time, is why would you want to abolish leap seconds ?

The main reason is that leap seconds are a huge pain in the butt for computers and networks

Bomazi (talk) 16:39, 17 January 2013 (UTC)

I think the pain in the butt is covered in the first paragraph of the Proposal to abolish leap seconds section. -—Kvng 15:07, 20 January 2013 (UTC)

Ok, I didn't read that part. Bomazi (talk) 21:56, 20 January 2013 (UTC)

One area where "traceable" time comes into play is in the financial markets where messages between traders and stock exchanges are time-stamped and people calculate transmission times between parties to the nearest millisecond and get excited once these take longer than 0.1 seconds. The only way that the times can be measured is for the transmitter to place a timestamp on their electgronic message and for the recipient to note the timestamp upon receipt. Martinvl (talk) 07:47, 21 January 2013 (UTC)