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Re: [Gnu-arch-users] s/GMT/UTC/

From: Phil Frost
Subject: Re: [Gnu-arch-users] s/GMT/UTC/
Date: Tue, 7 Sep 2004 00:08:26 -0400
User-agent: Mutt/1.5.6+20040722i

GMT is not UTC at all, at least if you are concerned with accurate time.
GMT is the observed time at the greenwich observatory, which is
determined by astronomical observances, not atomic clocks. It is
problematic for people who require accurate time because the earth's
rotation is not uniform.

UTC is determined by atomic clocks, and it is defined with a uniform
second. Leap seconds are used to keep UTC within 1s of GMT, lest UTC
would drift from the observed time on Earth.

All civil time systems use UTC. GMT is only of interest to astronomers.
NTP uses UTC, as well as any time you will get from any other time
service, radio, phone, or whatever. Thus, GMT is quite incorrect and for
very good reasons, albiet never more than 1s in error.

On Tue, Sep 07, 2004 at 02:00:17AM +0100, Andrew Suffield wrote:
> On Tue, Sep 07, 2004 at 08:14:29AM +1000, Zenaan Harkness wrote:
> > UTC is the newer name for GMT (actually, technically I thik they're
> > slightly different times, but anyway...).
> UTC is basically the world trying to deny that timezones originate in
> Greenwich by renaming it. Political correctness gone completely insane.
> > My recommendation is to use UTC rather than GMT. It's more accurately
> > defined.
> This is not true. It is differently defined, but no more
> accurately. It is also unsupported by unix platforms, and anything
> else based on time_t; they really give you GMT and call it UTC
> (inexplicably). It's actually off by a few seconds. UTC is not
> reliably defined in the future; you cannot say with precision what
> time it will be in one million seconds, other than "one million
> seconds from now"; there is no definition of how many seconds will be
> in a given year until that year occurs.
> It's not really the most sensible way to describe time.
> > It appears to me to be more The Standard.
> That's just masturbation.

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