Time measurement systems - Topics

The second has been defined by caesium-133 since 1967: counting 9192631770 oscillations replaced the rotating Earth Sealing a capsule with stainless steel and silica gel under inert gas What is a jiffy and why does its length depend on who is asking? How much does a country spend to keep one agreed second? Why do navigators still count time in degrees minutes and seconds? Why is the correct time something somebody has to run and pay for? Why do stock exchanges keep their own reference clock instead of trusting the wall clock? How did a sixty-day cycle end up organising Chinese year counting? Why the international date line bends around island groups instead of running straight The sidereal day is 4 minutes shorter and that is why stars rise earlier each night Why do we still split hours into 60 minutes instead of 100? Why does the SI second get redefined every few decades? Why does an institution publish its own time instead of pointing to the national standard? Why physics needed a second that does not depend on the rotation of the Earth Why is the month the loosest unit in any formal time system? Why does the definition of the second name a caesium atom instead of a physical artefact? How is a leap second inserted and who signs off on it? Why does averaging repeated timings not always improve the answer? Kodak ran on a 13-month calendar until 1989 and the International Fixed Calendar nearly won Whether a statute or an observatory actually owns a country's official time Why do metrology labs quote timing uncertainty in parts per billion instead of seconds? No whole-day leap rule makes the calendar year match the tropical year: the case for a 33-year cycle What actually happens at 03:14:07 UTC on 19 January 2038? What is the shortest interval a computer clock can actually resolve? Why did early mains-powered clocks depend on the grid holding its frequency steady? Why a few offsets sit 30 and 45 minutes off the hour Nepal set its offset 45 minutes off India's on purpose Why does a sundial need a correction table to tell useful time? What is the difference between resolution and uncertainty on a stopwatch spec sheet? Why did the plan to abolish leap seconds get pushed out to 2035? How far apart are TAI and UTC now and why does the gap keep growing? Why does Europe run at 50 Hz while the US runs at 60 Hz?