[LEAPSECS] happy anniversary pips

[Rob Seaman]

On Feb 10, 2014, at 9:57 AM, Warner Losh <imp at bsdimp.com> wrote:


> On Feb 10, 2014, at 9:02 AM, Rob Seaman wrote:

> 

>> Like I said, it is an attempt to confuse two different concepts.

> 

> We disagree here then. Atomic time is adequate for civil needs. The small divergence can be handled the same way we handle differences in time between the sun and the UT time now: time zones.


There hasn’t been the slightest investment of systems engineering in evaluating this notion of hiding variations in length of day in the timezone system.  We had a cat once that liked to hide squirrel parts under the doormat.  This is like that.

Note also that Tom Scott’s rant is titled “The Problem with Time & Timezones”:

	http://youtu.be/-5wpm-gesOY

Leap seconds are just a relish added at the end.  He clearly doesn’t perceive timezones as a solution, but rather as part of the problem.


> These times zones would move on a scale of multiple decades or centuries.


It’s almost as if the last decade-plus of discussions never happened.  Just continue to make the same empty unsupported assertion that doesn’t actually appear anywhere in the ITU proposal.  Please see many previous messages on this topic.  Here I’ll just note that these local updates would be clustered into extended periods of great confusion.  This isn’t an issue of two dozen timezones, but rather of the thousands of local jurisdictions that would be choosing what timezone to adhere to.  Some would toggle back-and-forth for decades during these transitional centuries as different political parties take power.


> This would suffice to keep the clocks on the wall aligned to the sun in the sky to the same error as we have today.


This confuses the reporting of local time with the maintenance of the underlying global timescale.  Future historians would curse our names for introducing vast uncertainty into future chronologies.  Predictions of future events (say, solar eclipses) would be unable to engage with a local time that might differ +/- one hour rather than a few seconds.

Equating this with daylight saving time is a particular red herring since only a small fraction of world participates in any of the variations of DST, but also since these changes wouldn’t be matched by a seasonal readjustment half a year later.  Each locality would be applying leverage to their particular timezone, but the timezone as a whole would have fuzzy edges, perhaps extending all the way through to the next era of confusion.


> It moves the alignment from one part of the system to the other. It doesn't confuse any concepts at all, but rather properly applies them to an alternative solution.


It certainly confuses the concepts that describe the actual physical situation.  And instead of keeping track of a single monotonic list of leap seconds, all software would have to track vast numbers of worldwide lists of local timezone peccadillos.  A single Olson tz database might no longer suffice since it would have to be normalized against individual tables for cities and counties, let alone countries and continents.  And pray, what happens in such a situation to the concepts of the prime meridian and the international date line?  I presume we’re to assume they stay put?  Why should they?

And for that matter I’m skeptical that it doesn’t confuse those few concepts you appear to care about.  You’d be requiring a complex tz schema (much more complex than currently) be added to many classes of software that simply get by with ambient UTC now.


> I get that people don't like this, and that there's some resistance to it on aesthetic grounds dressed up in the guise of technical arguments about universal not meaning what it has always meant, and that entrenched interests aren't unhappy enough with the status quo to risk changes...



Oh, if only I could lay claim to being an entrenched aesthete :-)

You don’t like arguments about Universal Time needing to continue to denote the same term of art it always has?  ISO disagreed with you enough to send a technical committee chair from Hong Kong to Washington, DC:

	http://www.cacr.caltech.edu/futureofutc/aas223/presentations/2-1-ISOterminologyAAS.pdf

Before it is used as implicit justification for redefining time policies worldwide, the ITU really ought to back it up with something more than “Hey, that sounds plausible!"

Rob