[LEAPSECS] What's the point?

Warner Losh imp at bsdimp.com
Tue Feb 8 18:05:43 EST 2011

On 02/08/2011 14:39, Rob Seaman wrote:

> Warner Losh wrote:


>> How would it be any different than today? Every few hundred years, the government moves the time zone. Heck, they do that now every few years anyway. Each government would be able to move it as they saw fit, or follow other government's leads. If the US move and Canada doesn't, then what's the harm?

> A) It would be taking what is currently a doubly indirect pointer and removing the layer in the middle. Dereferencing (converting to UTC) would no longer return a timescale stationary with respect to the synodic day. A robust system with innumerable connections across interfaces and stakeholders worldwide would be made brittle.

I don't see why it wouldn't. If you really need synodic day, DUT1
tables would give that. Most people want intervals or "do this when the
clock on the wall (not the sun) says 3 o'clock." But these problems are
well understood in a world where 2am might not exist on the clock on the

> B) Detailed expert knowledge would become necessary to answer even simple questions of comparing both clock intervals and Earth orientation questions either in a single place or across epochs and locations. "What year did Queensland shift from NEW-UTC+10h to NEW-UTC+10h30m? No, no! The second time?"

We have that today. Tell me, what time is it in Indiana? And how has
that changed over the past 20 years? Indiana used to follow DST, then
it didn't, then it shifted from one timezone to another. Oh, wait, only
some counties did this. Even the olson database won't give you all the
answers, but it will give you many of them.

> C) As pointed out on numerous occasions in the past, these kaleidoscopic timezones would accelerate quadratically just like leap seconds.

This problem isn't solved by this method either. True.

> D) It is asserted that interval timekeeping is hard to do. This would make it orders of magnitude more difficult for many classes of use cases. It ain't all about surfing the current instant into a future so bright we have to wear shades. (And I'm skeptical that sacrificing the UTC baby to the dingo on the beach really improves the surfing anyway.)

Given the yearly changes to the timezones today, I'm skeptical about
believing that adding a few dozen more every few hundred years would be
a huge burden.


>> I don't disagree that there's no plan.

> Another point of consensus!


> Rob



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