[LEAPSECS] h2g2

[M. Warner Losh]

In message: <20100903135619.6674.qmail at protonet.co.za>
            p at 2038bug.com writes:

: 

: > on the SAME time.  Nobody cares here that solar time and civil time

: > are 43 minutes off. 

: 

: *I* care 

: 

: but I'm not important - I'm just one person 


So do you live on a meridian where the solar time is within a few
seconds of the time zone?  Do you not follow daylight savings time?
You are already living at some offset to solar time that does and will
continue to dwarf any effects that accumulation of leap seconds will
have.  In my lifetime, there's been an accumulation of only 30
seconds if I read the tables right.  This is far smaller than the tens
of minutes I'm away from the meridian, and the semi-annual hourly
jumps.


: many people might care and many people are not getting to make

: the decision because the decision is being made for them. 


That decision was made in the last half of the nineteenth century:
Standard time already decoupled local solar time from the time that
the clocks read.


: further, it's not a decision we can *ever* go back on once it is

: made because reversing back to solar to time would be politically

: far too difficult to get collaboration on. 


Yes, but why do you care?


: therefore it is a decision that must be made very very carefully. 

: 

: that some NASA/ITU/whoever people find leap seconds "inconvenient"

: for programmers is NOT sufficient reason to ever have started

: pursuing this agenda. 


And why can't we just keep track of the accumulation for the
relatively small number of applications that care?  Why can't we
adjust timezones as the drift becomes larger every few hundred years
or so?  What genuine benefit is served by keeping UTC in sync to
England?  If corrections can be made and published, how are the
different astronomical applications made significantly harder?


: > leap hour will ever happen, but I won't be around to see it one way or

: > another. 

: 

: so really, your argument is to try convince people to only consider

: eventualities that occur within the space of their lifetime? 

: 

: darwin takes care of this attitude - it's sort of guaranteed 


Listen to my argument: I'm saying that a leap hour just doesn't
matter.  We've found a better way to keep time than the earth.  We
bollixed up the definition of the second to be about 2.54x10^-8
wrong.  This tiny error is why we have leaps seconds.  Had we defined
it to be 9192632003 instead of 9192631770 periods of the state
transition of Cs-133, the rate of accumulation would much smaller and
we'd only have to worry about leap seconds every decade or two.  And
we'd have the very real possibility of having both kinds of leap
seconds as the earth wobbles back and forth.

But, of course, redefining the second now to make up for historical
mistakes is out of the question.  It also is useless.  In a few
hundred years, no matter what we do, we'll have so many leap seconds
that we'll potentially have a huge problem on our hands.  The rate
will increase quadratically as the moon slows the Earth's rotation.
The long term trend is quite clear...  So eventually, leap seconds
will need to be thrown under the bus: they won't make sense anymore.

None of this has to do with my not caring about posterity.  The
reasons we tied ourselves to the earth historically is that it was (a)
the only place we cared about time and (b) the best time-keeper we had
until the middle of the last century.  Now that we're moving out into
space, and keeping time better than the Earth, it is time to question
how absolute are our needs for this synchronization, and whether the
complexity is generates is worth the cost it imposes.

Warner