Re: [LEAPSECS] two world clocks

From: Rob Seaman <seaman_at_NOAO.EDU>
Date: Thu, 20 Jan 2005 16:55:04 -0700

John Cowan replies to my question:

>> What exact future systems are we discussing that will both 1) require
>> the use of Universal Time and 2) not require a definition of
>> Universal Time that is tied to the rotating Earth?
> LCT is currently tied to UTC, and converting a count of SI seconds to
> a UTC time is currently (a) annoying and (b) depends on updating
> tables.

Civil time is indeed tied to Universal Time, and UT is defined to be
(basically) equivalent to Greenwich Mean Time. This whole discussion
is about some obscure committee seeking to change a standard that was
founded, more-or-less in its current form, at the Longitude Conference
in 1884 (historical corrections welcome, but pick your nits somewhere
else). The attendees of the Longitude Conference were high level
representatives of the world's great powers. The attendees of the
obscure meetings related to the current leap second debate are
themselves obscure - well - nerds, like all of us reading this list.

To comment on your particular points:

a) Clearly I'm annoyed about other aspects of this situation than you
are. Why should the annoyance of members of the ITU matter more than
the annoyance of other parties?

b) Currently the tables are maintained and updated by members of the
precision timing community who should indeed be commended for their
excellent work over the last quarter century and more. The proposal on
the table would require all 6+ billion of us to keep his or her own
tables up-to-date. The current situation is better.

> Wall clocks need to run in LCT, which is currently founded on UTC.
> Most people don't need precision time-of-day (which should be rightly
> called "Earth angle" and measured in SI radians). They just need
> there to be a rough correlation between LCT and the sun, and several
> hours' discrepancy can be tolerated. Just go to Urumqi, or Detroit if
> Urumqi is too remote.

Isn't this just a wee bit arrogant? (I toned that down from another
word starting with "r".) People need good sources of time for a
variety of reasons. We are discussing a complete abandonment of the
provision of Earth "rotation information" to the civilian public
worldwide. I won't belabor the point of why I think that is bad. The
question is, why aren't the precision time keepers debating ways to
improve the delivery of time signals to the world community, rather
than debating how best to sneak through a proposal to degrade time

>> It ain't your clock - it's *our* clock.
> Eh? Who are "you" and who are "we"?

I would think that is obvious. "You" refers to a couple of dozen
temporal bureaucrats who likely don't care enough about this issue that
they find themselves playing politics with to even bother reading, let
alone replying to, this mailing list. "We" refers to the six billion
(and growing) of the rest of us.

Civil time is a hell of a fundamental standard to be so whimsically
managed. If there are improvements needed - in the short term - to the
standard, let's hear the evidence. That long term changes are needed
is no surprise (see for my analysis
of the situation), but what the hell is the hurry?

Rob Seaman
National Optical Astronomy Observatory
Received on Thu Jan 20 2005 - 15:55:12 PST

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