In message: <[EMAIL PROTECTED]> John Cowan <[EMAIL PROTECTED]> writes: : > But how in practice is it envisaged that a scheme : > for migrating time zones versus TAI would work, precisely? : : Straightforwardly. Each locality decides when and how to adjust both : its offset from TAI and its seasonal transition function (if any), : just as it does today. What we abandon is a universal time tightly : synchronized to Earth rotation in favor of a universal time : independent of earth rotation plus 400+ local civil times roughly : synchronized to Earth rotation containing various glitches.
No matter what we do with leapseconds, there are still all those time zones. The problem with stopping leap seconds altogether is that the legal definitions of time, although quite varied, are all about the same as UTC as it exists today. They are close enough that most countries have adopted UTC bureaucratically rather than legislatively. The official time for the US, as published by the folks at NIST, is UTC. The US law says mean solar time, as determined by the Secretary of Commerce, who has delegated it to the Time and Frequency division of NIST, who in turn use UTC. NIST could easily use a different schedule for leap second insertion (it could have inserted the leap second in civilian time at the end of any day it wanted to and still maintained the mean solar time legal requirement). However, since UTC is a recognized, international standard, the US went along and did its leap second according to that standard. This is a explicit choice that someone, somewhere had to make, even though it is arguably the best choice to make (wouldn't want to be the odd man out in civil time, think of the impact on business). The combination of UTC approximating the legal time is so man nations, as well as the need for international consensus among lots of parties with divergent views for any changes to the current system is why we'll likely not see significant changes any time soon. The best we can hope for is that something will be done to change their unpredictable nature given that we have good forcasting tools at our disposal. Warner