Abstract:
This special timestamp of 23:59:60 will no longer appear in the future!
According to the State Administration for Market Regulation, it was recently revealed that the 28th International Conference on Weights and Measures (CGPM) held in Versailles, France from October 13th to 15th passed the above resolution. The resolution stipulates that starting from May 20, 2027, the insertion of leap seconds will be stopped globally, and the maximum allowable deviation between Coordinated Universal Time (UTC) and Universal Time (UT1) based on the Earth's rotation will be relaxed to 3600 seconds (1 hour).
This means that the leap second mechanism, which has been running for more than half a century, has officially withdrawn from the stage of history.
It is understood that the birth of leap seconds stems from the fact that atomic time is out of sync with the Earth's rotation time: Atomic time stipulates that a day is fixed at 86,400 seconds, but the Earth's rotation speed is not constant, and the two will slowly accumulate errors.
In 1972, the International Conference on Weights and Measures set a rule that when the difference between atomic time and universal time is close to 0.9 seconds, an extra second will be added or subtracted to align, which is a leap second. In the past few decades, we have basically encountered positive leap seconds that add one second.
However, observations have found that the earth's rotation has accelerated periodically since 2015, and the length of a day is actually shorter than the 24 hours of the atomic clock. If this trend continues, the future will require the implementation of unprecedented negative leap seconds – not adding a second, but removing one.
At present, most infrastructure and code systems have only been adapted to positive leap seconds and have no actual experience with negative leap seconds. Once triggered, the risk of failure is difficult to predict, which is also the reason for promoting the retirement of leap seconds.
For our country, canceling leap seconds will directly reduce operational risks in many key areas.
The punctual timing system of China Time and Frequency Organization no longer needs to insert leap seconds, and Internet timing services no longer need to use leap second smoothing schemes to correct jump seconds, and operation and maintenance risks are reduced;
5G base stations, power grid phasor synchronization, financial timestamps, etc. no longer process the insertion of positive and negative leap seconds, improving the continuity and reliability of operations;
It is no longer necessary to insert leap seconds into the design of the Beidou satellite navigation system, which will reduce the possibility of errors in time coordinate conversion.
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