[time-nuts] FW: Bulletin C number 30

Poul-Henning Kamp phk at phk.freebsd.dk
Tue Jul 5 02:29:44 EDT 2005

In message <20050704.212118.87245102.cfmd at bredband.net>, Magnus Danielson write

>> And btw, it probably would not even be a leap-second for him, since
>> general relativity would take its toll.  I'm not sure my grasp of the
>> math is good enough to figure out how long his leap-second would be.
>> Instead, if we abandon leap-seconds, then we finally have a _truly_
>> universal timescale.
>> It will not be locked to any more or less random piece of geophysics,
>> anyone with a cesium clock and a set of gen-rel coordinates will be
>> able to figure out what time it is, and time intervals can be measured
>> and compared without weird gottchas.
>No. You are missing a detailed refinement in the definition of a second, it is
>assumed that the Cesium clock is at sea-level.

Sea-level on this planet, yes.

If you are on a different planet in a different orbit and a differnet
rotation period (and axis!), general relativity takes a toll.

If you bring a HP5071A to Mars, it will give you a wrong length of

>Considering how time-zones is set, I start to wonder. Look at the time zones
>in South America and you see what I mean.

Just look at Europe :-)

>> The other half is that leap-seconds are just not testable in a computer
>> setting, and therefore I am sure that any cost of dropping them will
>> be totally offset by the savings in the IT industry.
>I am not even sure that the IT industry is really spending a whole lot on this
>issue. Most of them is to the best of my knowledge fairly ignorant to this
>among other problems. Just having charging systems track UTC through NTP would
>be a huge step forward IMHO.

Well, I think the disruption is obscured by the lack of implementation.
As more systems implement leapseconds (through NTP or otherwise) we will
see more applications which didn't do it quite right.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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