Re: [LEAPSECS] Time after Time

From: Poul-Henning Kamp <phk_at_phk.freebsd.dk>
Date: Sun, 23 Jan 2005 10:00:53 +0100

In message <41F2BB07.191.8BCA0E87_at_localhost>, "Daniel R. Tobias" writes:

>Some of the proposals, however, seek to decouple civil time
>altogether from solar time, an unprecedented step which would
>possibly lead to day and night being completely reversed; any "leap
>hours" that prevented this would, if ever implemented, be even more
>traumatic than leap seconds are now.

This claim of trauma is very interesting, can you please back it up ?

First off, we could give 100 years of advance notice (at the cost
of some precision) for a leap-hour, and that would very likely be
enough for a couple of generations of engineers to work to get ready
for the big day.

Second, they already happen here twice a year, and by now even
Microsoft has gotten it right.

>In addition to being historically unprecedented, such a move would be
>illegal in the United States and some other countries, which have
>laws explicitly defining their time zones based on solar mean time,
>unless such laws were changed.

The laws, wisely, do not say how close to solar mean time, and parts
of USA already have offsets close to or exceeding one hour anyway.

>Now, if a time standard is to be defined based solely on constant SI
>seconds, with no reference to astronomy, then why even include all
>the irregularities of the Gregorian Calendar, with its leap year
>schedule designed to keep in sync with the Earth's revolutions?

You are confusing two things here: Length of day and length of year.
In this context they are totally decoupled and unrelated.

--
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.
Received on Sun Jan 23 2005 - 01:11:08 PST

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