Markus Kuhn wrote: > ... because it > seems inconvenient as long as politicians worldwide can't agree on > common dates of switching between summer and winter time. ...
Well, would you vote for a politician who would agree to ending summer time on the same day over thw whole world - both northern and southern hemispheres? More seriously, I'm not sure why a common date is required. First there's a discontinuity in TI, say at midnight December 31st/ January 1st, resulting in an instaneous change in the offsets of all the timezones around the world - they remain continuous at this point. Then, at convenient times during the year the timezones adjust so that, by the end of the year, they are back at their original offsets. Obviously it would be nice if they did this together but it's not essential. I guess timezones which don't normally implement daylight saving might choose to change at the same time that neighbours which do change. --------------------------------------------------------------- I realise that this is something of a "what if..." conversation by people who are not overly impressed with the ITU proposals but I'd just like to poke in my view that I think this idea of dropping leap seconds in about 20 years and replacing them with leap hours is just about the worst possible "solution": - For the next 20 years we'll be stuck with leap seconds but it'll be even harder than now to get people to take the matter seriously because they'll be going away anyway. - Our generations have dumped enough physical rubbish on the future without leaving this "timebomb" in the paperwork, too. My humble opinion is that in 1972 leap milliseconds should have been introduced (i.e., set the UTC day length to an integer number of milliseconds, e.g, 86 400.002 seconds, announced well in advance like the current leap seconds) instead of leap seconds. 99% of people can safely ignore leap seconds and 99% of those left could ignore leap milliseconds (e.g., users of the currently broadcast DUT1 to 0.1s precision) leaving only a few left to really worry. The only snag I can see with leap milliseconds would be the "glitch" in the time signal as a frequency standard over 00:00:00Z - which it would be easy to cancel out because presumably the UTC LOD would be broadcast, probably in the bit positions currently used for DUT1. The big advantage of leap milliseconds is that they would happen often - not like leap seconds which happen so rarely that they might not appear at all in the development cycle of many systems. However, I think there would be a real outcry if an attempt to change to leap milliseconds were to be made now. We've got leap seconds and will have to live with them for a good few years yet. We might as well concentrate on doing this methodically rather than trying to "fix" the problem by storing up a bigger problem for the future. There is probably no significant difference between a "short term" solution which works for the next 20 years and a long term solution which obviates any supposed need for change. Ed.