Re: [LEAPSECS] Consensus rather than compromise

From: Rob Seaman <>
Date: Mon, 29 Aug 2005 16:38:56 -0700

On Aug 29, 2005, at 2:12 PM, Clive D.W. Feather wrote:

> And, by the way, the "GMT standard" is *NOT* synonymous with UTC;
> it is (IIRC) UT1.

The original UTC standard (i.e., CCIR 460-4) stated:

     "GMT may be regarded as the general equivalent of UT."

UT1 and UTC are both representations of Universal Time. In a world
with one-hour wide time zones, the idea of a leap hour is equivalent
to the deprecation of the idea of Universal Time.

> I suggest that fiddling with the hourly shifts will continue every
> few years ad nauseam, so one more reason for doing so won't bother
> anyone.

Folks keep mentioning Indiana as a special case. More than one-
fourth (13) of the states are cut by time zone boundaries: http://

One asserts that UTC, GMT and the standard time zone system are
precisely what allows local governments the flexibility to make such
decisions for themselves. The whole point of DST (in its modern
context) is to conserve energy: DST exists precisely because an
hour's difference in the time of sunrise can be valued as a large
economic factor.

>> Contrast this with a well-formed consensus - several disagreeing
>> factions are locked in a room until they all agree on a common
>> vision of how to proceed.
> That works when it works. Not when there are irreconcilable
> differences in the "general requirements and objectives".

It would be hard to characterize the squabbling over the last few
years as irreconcilable differences. We haven't even succeeded in
getting an appropriate selection of the affected parties assembled
either online or face-to-face. Would love to see a well advertised
UTC workshop organized in DC (or Orlando, for that matter). It would
be delightful if folks were to arrive with an open mind, as well;
only one option has ever been considered. We may be in the process
of shooting that single option down, but that doesn't mean we can't
identify a consensus position around some other proposal.

Time is on our side.

>> What is needed is civil time to continue to reflect solar time as
>> it has since literally the dawn of time.
> Within a couple of hours plus or minus.

Again, this confuses secular effects with periodic effects. Even the
most extreme "nuke the leap second" position that has been expressed
has assumed that civil time corresponds to a high level of precision
with solar time. A proposal to identify civil time with TAI (or TAI
plus some constant) is only being entertained because the SI second
approximates 1/86400 of a mean solar day to a few milliseconds per
day. I happen to think those milliseconds matter a lot - others
think they don't matter at all - but we already agree on a common
position that civil time needs to mimic solar time for most purposes.

We should be willing to consider alternatives that are quite
different from the status quo. That is the intent of the decision
tree that has been posted. But do any of us really expect that we
will end up with a civil time standard corresponding to an 18 hour
day? Or even with a civil day that corresponds to the actual
sidereal period of the spinning Earth, 86164 SI seconds? Rather, I
think we all expect that any civil time standard that is viable over
the next few centuries will correspond very closely to the mean solar
day length. (And I'm doubtful that any of us would want to live on a
planet or in a society for which this assertion was false :-)

With no sense of irony - thanks for the excellent discussion.

Rob Seaman
National Optical Astronomy Observatory
Received on Mon Aug 29 2005 - 16:39:38 PDT

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