[LEAPSECS] What's the point?

Rob Seaman seaman at noao.edu
Wed Feb 9 12:48:14 EST 2011

Warner Losh wrote:

> It is a lot easier to adjust by an hour for local time than it is to have a leap second every month, or more often.

You assert this position. I dispute it.

"Adjust *what* by an hour"? PHK's position is that hundreds of local governments (that he appears to consider beneath contempt) would have to act separately or severally during each adjustment. By comparison, a leap second is introduced by a central authority and is ignored by microwave ovens and set-top boxes and in general most clocks worldwide. Even if one-a-day is introduced this would be the case. A leap-hour-by-whatever-name cannot be ignored even by a microwave oven and no central authority would exist.

>> The current leap second policies are constrained to twice per year - this would correspond to a timezone do-se-do of 1800 years. The actual standard, though, is 12 per year - that brings it down to 300 years, which seems similar in level of intrusiveness. Larger interruptions must occur less frequently to be tolerated.


> I'm not sure I follow this point...

Timezone "pressure" would have to be released when 3600 leap seconds accumulate. Consider earthquakes. The longer the period of quiescence, the larger the quake when it happens. Since it is a tenet of the rubber timezone notion that there would be no central authority, each timezone quake would have technical, historical, legal and economic aftershocks lasting possibly decades as one locality after another shifted.

> The US changes its timezone rules on average every 10 years (DST has been uniform for 45 years or so and has changed 5 times). Tweaks to the US timezone rules happen annually for different parts of the country (this country moves from this timezone to that, etc).

Now you are comparing rubber timezones to daylight savings. Compare also with:

On Feb 9, 2011, at 1:40 AM, Clive D.W. Feather wrote:

>> <falls about laughing>


>> I was involved in a murder case where the police investigated the wrong

>> person because they hadn't realized the difference between UTC and BST.

>> What makes you think that financial lawyers will think of it.

Is this something we want more of in the world?

Continuing, I said:

>> Leap seconds would be much more robustly tolerated into the far distant future than rubber timezones.

Warner said:

> what are rubber timezones that you talk about? I don't think we're talking about the same thing.

Folks have talked about rubber seconds around here for a long time. This notion that zero planning is needed because timezones are deemed infinitely compliant could thus be called "rubber timezones". I find the notion silly, but more than that I find it silly that we're pretending that this is the ITU position. The ITU position is to ignore the whole thing and fail to plan for the inevitable eventualities of ceasing leap seconds.

> The idea that's been put forth is that the transition would be made all at once. Eastern Time zone would go from TI-5 to TI-4, most likely by failing to fallback one year in the fall.

Exercise for the class: Which is it? Will the governments act separately or together? How will governments north and south of the equator coordinate given that daylight saving time occurs in the local summertime during opposing seasons? Etc and so forth.

The folks on this list appear to have reached consensus that some mechanism (whatever it is) is required for managing leap-second-equivalents. The ITU draft includes no planning for such. Do they disagree with all the diverse voices on this list? Or do they merely find it more expedient to ignore the whole thing - for a season or a day or a century - and to leave their mess for their grandchildren to clean up? (Current astronomers, etc., would of course have to deal with the consequences immediately since it will break all our software.)

Is it really controversial that the ITU should be expected to plan for the consequences of their actions?


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