On 2022-10-05 06:02, Paul Gilmartin via tz wrote:
Smearing has proven less disruptive to computer systems than leap seconds. I still favor UT1 as a generalization of smearing.
Unfortunately the precision of UT1 is only about ms, limited by its predictability: too low for current commercial requirements, and insufficently accurate for engineering uses. https://www.nist.gov/pml/time-and-frequency-division/time-services/ut1-ntp-t...
Are pulsar frequencies measured with TAI or UTC?
All three use SI seconds currently.
When Standard Time was established in the 19th Century, the width of a time zone was about a day's travel distance.
More like a week for most. An hourly zone is about 1600km/1000mi or about 40hr travel at 40km/hr 25mi/hr (which is still about the average NA freight train speed, due to length and weight of loads, over variable quality trackbed, and lack of isolated or dedicated routes). The Pony Express took 10 days to go about 3000km 1900mi - nearly two zones. It would nowadays take over a day by NA long distance rail passenger service: Toronto-Vancouver express takes 96hr for about 4400km 2700mi - 45km/hr 28mi/hr.
People cling desperately to the alignment of clocks with solar time.
Most legal systems are still based on solar time, used as civil time: why leap seconds are required if you base time keeping on caesium atomic microwave emission frequency derived seconds. Many countries wish to avoid the legal wrangling, duration, and costs of rewriting a lot of legislation, and then political wrangling to try to pass it. You may imagine the irrational bases of many arguments! ;^> Previous posters have mentioned countries likely to wield veto power over any changes to the status quo like dropping it. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised. [Data in binary units and prefixes, physical quantities in SI.]