[time-nuts] The future of UTC

Jose Camara camaraq1 at quantacorp.com
Fri Jul 15 10:54:02 UTC 2011


Steve:

	The scientific community needs a well defined second, physically
reproducible and stable. Something like the old meter platinum bar. In fact,
look at meter in Wikipedia, very similar issues, with Earth as a basis for
the reference at some point. Current definition is based on length traveled
by light in vacuum in one second. Right there - making the second depend on
Earth rotation, changing it daily, hourly to follow the capricious wobbly
Earth would change the meter length just as often. Basically 'turns back the
clock' hundreds of years in accuracy, stability of the second.

	Now the second definition relates to frequency accuracy, there is no
phase information. Nothing like a femtosecond 'ball drop' somewhere that
would define an absolute time.

	Once the second became atomic, the Earth variations and slowdown
drift (ultimately it would show the same side to the Sun like the Moon does
to Earth, in a few buzillion years - astro-nuts enlighten me) become an
issue, as we don't want our buzillionth generation descendants seeing
sunrise at 3am (although they would get off work at 2pm!). Once the Earth
day equals the Earth year, what do we do? Let's plan ahead for the UTC at
that point. Nice wall calendars, January First only! And it is a Holiday!


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Steve Rooke
Sent: Friday, July 15, 2011 3:18 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The future of UTC

Well, instead of leap seconds which seem to be the biggest bug bear
for everyone, keep the second as 1/86,400 of the earths current
rotation and adjust the factor used in the calculation of atomic time
on a regular basis. No more leap seconds just leap atomic division
factor. Unless you can try and convince the world that all this hours,
minutes and seconds thing will have to change and some new system for
defining the day with the granularity of some arbitrarily chosen
factor of atomic time (which was in line with the earth's rotation 50
years ago or so) is worked out. The day that the second was defined in
an atomic form has always meant that it bears little relationship to
the idea of a second that was held before it and is used in the real
world of wall clock time now.

Yes, I'm well aware that this causes major impracticalities for
technical and scientific users but the current system of linking
atomic time to wall time obviously has its problems. Maybe that
original linkage decision was a bad idea and the definition of the
wall clock second should go back to the astronomers.

Steve

On 15 July 2011 21:36, cook michael <michael.cook at sfr.fr> wrote:
> Le 15/07/2011 10:33, Poul-Henning Kamp a écrit :
>>
>> In message<4E1FFA88.9050400 at sfr.fr>, cook michael writes:
>>
>> Michael, there are a few details you overlook, and rather than
>> repeat myself, I'll point you at an article I wrote for Queue and
>> Communications of The ACM, trying to lay out the bits:
>>
>> http://queue.acm.org/detail.cfm?id=1967009
>>
> Thanks for your ref.  I am aware of the shortcomings of the present scheme
> and am not particularly pro leap second. It seems to me that the right
> questions are not being addressed and certainly the proposition for change
> as expressed and to be voted on in 2012 is premature. The US are just
> wanting leap seconds abolished without proposing alternative schemes
> covering all the requirements of time signal users.    Once they have been
> defined , recommendations can be considered.  Till then , fix the bugs.
>
>
>
>
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-- 
Steve Rooke - ZL3TUV & G8KVD
The only reason for time is so that everything doesn't happen at once.
- Einstein

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