[LEAPSECS] The Once and Future Time

[Rob Seaman]

Good to see that enthusiastic discussions continue :-)  Those new to the list might review previous threads that touch on all the recent talking points.  See under discussions near the bottom of:

	http://www.cacr.caltech.edu/futureofutc/links.html


On Jan 18, 2014, at 6:54 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:


> In message <52DA8247.70005 at rubidium.dyndns.org>, Magnus Danielson writes:

> 

>> but about what "Universal" in UTC actually means.

> 

> What it *meant*.


Universal Time means (and has meant) mean solar time based on the synodic day.  A time scale that means something else should be called something else:

	http://futureofutc.org/aas223/presentations/2-1-ISOterminologyAAS.pdf


> That may not be the same thing people mean these days, when they

> plunk down robots on different pieces of orbital debris.


Day means synodic day on other pieces of orbital debris, too:

	http://futureofutc.org/preprints/files/28_AAS_13-515_Seaman.pdf


> Remember:  Standards should be written for the future, the past

> don't care if you change them.


As the recent back and forth about proleptic time scales illustrates, our civilization has many historical dependencies on time.  It would generally be a bad idea to yank the rug out from under any international standard, but much more so for issues of dates and times that will continue to reside in documents and databases.  Prior leap seconds will not vanish from the historical record under any scenario.

UTC under the current definition should be retained for backwards compatibility.


On Jan 18, 2014, at 2:11 PM, Warner Losh <imp at bsdimp.com> wrote:


> Leap seconds are evil and must die, leaving alignment to the sun to local governments. Others may have a contrary opinion.


...but tell us what you really think ;-)

Apparently Tom Scott is one who has a contrary opinion:

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

considering most of his rant is about the peculiarities of locally managed timezones.  How many more quarter-hour timezones do you think the world needs?

It may be worth reviewing the many previous messages on this list regarding the naive and dangerous notion of obscuring knowledge of Earth orientation within psychedelic timezone management at the whim of local authorities.

On Jan 18, 2014, at 1:52 PM, Stephen Scott wrote:


>> Time implementations that have evolved over time are no longer good enough.

> 

> How exactly are they no longer "good enough?" They are certainly stunningly adequate for most users.


I'm at a loss reconciling your "stunningly adequate" with "evil and must die".


> GPS handles these needs to three orders of magnitude better than you request.


Right.  Ceasing leap seconds would not improve access to a widely available interval timescale, it would simply destroy access to our Earth orientation timescale.

Systems, software and civilization depend on both interval time and Earth orientation time.  We should be careful about tampering with these critical resources, apparently only in support of some dreary turf battle among special interests.

	"Everything not forbidden is compulsory"
	  - Murray Gell-Mann quoting T.H. White

Rob Seaman
National Optical Astronomy Observatory