Boffins debate killing leap seconds to help sysadmins

Bureau International des Poids et Mesures contemplates upgrade for UTC

Swiss iOS clock

Boffins from the International Telecommunications Union (ITU) and the International Bureau of Weights and Measures ( known as the BIPM for its French name: Bureau International des Poids et Mesures) have met to discuss redefining time.

Specifically, they're keen to redefine Coordinated Universal Time (UTC), the international time standard that is the precision version of Greenwich Mean Time (GMT). So precise is UTC that ITU and BIPM boffins sometimes slip an extra second, called a “leap second”, in at the end of the year so that the time it takes the Earth to rotate is accurately expressed by timekeeping apparatus.

Those extra seconds may ensure that everything adds up when boffins calculate UTC, but folks who depend on the standard have to update their systems whenever a leap second is added. Sysadmins are among the groups inconvenienced by leap seconds, as while network time protocol (NTP) is aware of them and includes them in its updates, not every device is connected to an NTP server.

ITU and BIPM chaps wonder if a “continuous time scale” that doesn't need leap seconds might be a better idea.

The good news is that a continuous time scale already exists in the form of the International Atomic Time (or Temps atomique international (TAI)). The TAI has been up and running since 1958, but as this presentation (PDF) delivered to the BIPM's Consultative Committee for Time and Frequency (CCTF) last week states “TAI is not an option for applications needing a continuous reference as it has no means of dissemination, and it is not physically represented by clocks.”

On the agenda at last week's meeting was figuring out a continuous time scale everyone is happy with and that can also be disseminated to those who need it. Any proposal will be taken to 2015's World Radiocommunication Conference.

If that meeting succeeds in implementing a continuous time scale, this (PDF) presentation to the CCTF says the effort will be worthwhile.

“If leap seconds are eliminated from UTC, there will be no perceptible impact on social activities and conventions,” writes delegate Robert A. Nelson, “but there will be significant reduction in the risk to national and international infrastructure and significant cost reduction in their implementation.” ®

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