[time-nuts] Re: UTC

Poul-Henning Kamp phk at phk.freebsd.dk
Wed Jul 27 01:37:47 EDT 2005

In message <42E6C1F7.3040002 at erols.com>, Chuck Harris writes:
>Poul-Henning Kamp wrote:
>> In message <4A4B4876-7D7F-4D81-AE31-26A757E7AA81 at noao.edu>, Rob Seaman writes:

>Now, for 3 t-shirts Poul, reread Rob's last paragraph, but this
>time with your blinders removed.

I'm still trying to get the same basic point across, and answering
his last paragraph would just have repeated the message yet again:

To 99.999% of the Earths population, the Earth is geophysics, not

For almost the entire population, time is defined as SI seconds,
60 of which is a minute, 24 of which is an hour, 365 of which is a

There is a well defined formula that streches indefinitely into the
future, which inserting an extra day almost every fourth year, for
reasons most people do not claim to fully understand.

I fully agree with Rob that there are prefectly valid physical and
astronomical reasons for the leapsecond, but I keep trying to tell
him that like so many other metrological details, the everchanging
mass of the kilogram prototype comes to mind, it will have to be
a dirty little secret in the scientfic world:  We cannot economically
justify imposing leap seconds on the rest of the world with six
months notice.

Leap days are economically feasible because most people have a big
disconnect between the concepts of timekeeping and calendar but
mostly because the rule is predictive and can be embedded safely
in computers which are going to run autonomously for years.

Leap seconds are too small for programmers to have heard about or
care about, they are unpredictable for more than six months at a
time and untestable in practice.

Robs position, as I understand it is "fine, fine, fine! just don't
call it UTC!" and that is not economically feasible either IMO.

Leapseconds is not a scientific or astronomical issue, they are
an economical issue.


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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