Warner Losh imp at bsdimp.com
Tue Jan 17 12:44:18 EST 2012

On Jan 17, 2012, at 6:26 AM, Daniel R. Tobias wrote:

> On 17 Jan 2012 at 10:12, Ian Batten wrote:


>> Which is a deal breaker, because whatever a country adopts as civil

>> time, that's going to be the primary payload on its national

>> broadcast standards


> And what if some countries use a solar-time-based standard and some

> an atomic-time-based one (as is actually the case with current law),

> and hence some broadcast a leapless scale and others either continue

> leap seconds or use some other scheme to keep their broadcasts in

> approximate sync with UT1? Then we'd have a complex worldwide

> situation where different countries' civil times are no longer round

> multiples of hours (or occasionally half or quarter hours) from each

> other, but vary by seconds (or maybe even fractions of seconds if the

> solar-based countries go back to rubber seconds).

The ITU standard is the standard for radio broadcast time. That's why everybody broadcasts UTC (+/- some fixed offset) today. To conform with international standards, they would broadcast the new timescale.

I think we'd wind up with the situation we have today: The law may say 'mean solar' but everybody de-facto goes with UTC because that's what the various national labs say the right time is. So the more pertinent question will be 'what are the labs going to do?' since that's what everybody, or nearly everybody, will blindly follow. They are the domain experts, they deliver time to me, why would I use anything else[*]?

So one could see a chaotic situation developing, but in the absence of a centrally recognized authority for things like leap seconds, I suspect that such chaos won't develop. The national labs all run on atomic clocks, and those clocks tick in SI seconds and unless there's some international agency like IERS to coordinate the insertion of leap seconds, the 'status quo' momentum will tend for everybody to do what's easiest, which is to do what they are doing and never insert a leap second into things. Since the international cooperation on TAI won't end, and since everything flows from that time scale as far as realized time scales, and since the delta between this and the pedantic UT will be small for the next 20 years, I don't think the chaos that you described will happen. Who wants to be the first lab that's the "odd man" out? The time community is very tight knit and my sense is that peer pressure will keep everybody doing the same thing.


[*] Unless I'm an astronomer or care which way the earth is pointing to sub-minute accuracy.

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