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Subject: [IP] Leap second considered harmful

  • From: David Farber <dave@farber.net>
  • To: ip@v2.listbox.com
  • Date: Tue, 03 Jan 2006 16:51:59 -0500



Begin forwarded message:

From: Bob Frankston <Bob19-0501@bobf.frankston.com>
Date: January 3, 2006 3:49:56 PM EST
To: &quot;'Jonathan Thornburg'&quot; <jthorn@aei.mpg.de>, &quot;'David Farber'&quot; <dave@farber.net>
Cc: ip@v2.listbox.com, &quot;'Bob Frankston'&quot; <Bob2-19-0501@bobf.frankston.com>
Subject: Leap second considered harmful


Thanks for the pointer. http://www.cl.cam.ac.uk/~mgk25/time/ metrologia-leapsecond.pdf.

This is useful because it strongly affirms my claim that the leap second is a bad solution to a non-problem.

&#x201C;The primary reason for introducing the concept of the leap second was to meet the requirement of celestial navigation to keep the difference between solar time and atomic time small. However, the motivation for the leap second has diminished because of the wide availability of satellite navigation systems, such as GPS, while the operational complexities of maintaining precise timekeeping systems have made the insertion of leap second adjustments increasingly difficult and costly.&#x201D;

In option #7 they note &#x201C;It is thus unlikely that the growing difference between clock time and levels of daylight would be noticeable for the foreseeable future.&#x201D;
Perhaps they are trying to fill up 21 pages in order to get published but it is quite clear that they are saying that the leap second only exists because of modern precision &#x2013; the very same tools that give us the precision also give us the means for dealing with it as a correction factor.


Too bad they can&#x2019;t come right out and say &#x201C;get rid of it&#x201D; but they come quite close.

I&#x2019;ll admit that I&#x2019;m bad at this kind of stuff because if the high order bit is wrong I don&#x2019;t spend time on the low order bits. IN this case the high order bit is to introduce perverseness in basic computation rather than keeping it confined to a correction factor. I can only wonder why we ever allowed the leap second to happen in the first place.

It would be nice to get back on track and declare SUT (Simple Universal Time) based on time as if the leap second were never introduced and let the use of UTC be deprecated. That would add another set of calls to the time libraries but the code would be the same as the current UTC code since we&#x2019;ve vary rarely implemented real UTC but it would accommodate programs that actually did.



-----Original Message-----
From: Jonathan Thornburg [mailto:jthorn@aei.mpg.de]
Sent: Tuesday, January 03, 2006 10:37
To: David Farber
Cc: ip@v2.listbox.com; Jonathan Thornburg; Bob Frankston
Subject: Re: [IP] more on Leap second fight brewing



Bob Frankston wrote:

> I still don't understand the purpose of leap seconds on the human scale. I

> understand correction factors but I don't understand this fundamentalist

> view of time.



There's (what I think is) a nice summary of the issues at

   http://www.iop.org/EJ/article/0026-1394/38/6/6/me1606.pdf

which can also be found (free!) at

   http://www.cl.cam.ac.uk/~mgk25/time/metrologia-leapsecond.pdf



ciao,



--

-- Jonathan Thornburg <jthorn@aei.mpg.de>

Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein- Institut),

Golm, Germany, &quot;Old Europe&quot; http://www.aei.mpg.de/~jthorn/ home.html

    &quot;Washing one's hands of the conflict between the powerful and the

     powerless means to side with the powerful, not to be neutral.&quot;

-- quote by Freire / poster by Oxfam



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