18 Nov 2022 - The fate of the leap second may be decided today at Versailles

[gary]

The International Bureau of Weights and Measures (BIPM – Le Bureau Internationale Poid et Mesure) meets today, November 18 2022, in Versailles, to vote on Resolution D, which may determine the fate of the "leap second".

The world has several standard time references and a set of standards as to how they relate to each other. The major ones are :-

TAI - is kept by atomic clocks.

UT1 - based on the Earth's rotation wrt a reference frame pegged to the positions of quasars typically billions of light years away.

UTC - a synthetic time standard which is based on TAI but kept within 0.6 seconds of UT1 by inserting or removing leap seconds now and then as the Earth rotation slows down or speeds up. Originated in 1972, currently TAI − UTC = 37 seconds.

If leap seconds are abandoned, slowly over the centuries what time the sun and stars appear to rise and set with respect the civil time shown on your watch (or phone, etc), will change in part as a function of that TAI - UTC difference.

Depending on what is decided - or not - in France today, we might, for example, see a resolution that adopts a new time standard called International Time (TI) that replaces the current UTC standard (which is used to determine your local time according to your time zone) and which may be locked to TAI and no longer be adjusted for Earth rotation.

[Peter Ward]

Clocks no longer in sync with the earth's rotation?
Bah! Humbug I say!

Reminds me of this old gag.

A physicist is walking down the street, and sees a sign in a shop front that reads "Watch repairs done here". Needing his watch serviced, he goes in and is greeted by a fellow in the front office who he asks whether he can repair his watch.
The fellow replies, "Oh heavens no, we don't do that sort of thing here".
Puzzled, the Physicist points out the sign in the window.

"The sign? You need to understand , we are all mathematicians here....we just make signs...."

[Steffen]

I wonder what the benefit of that would be. Synthetic time (or calendar) references, including the leap seconds and leap years they bring along, are easily handled by computers and don’t seem to be causing any issues. Abandoning them would cause the sun to be high in the sky at midnight in the distant future.

[gary]

Hi Steffen,

You would hope that all software practitioners would get this right.
However, recent history is littered with examples of system failures as a result of leap seconds and the software not handling it correctly.

One of the more well publicized examples was the Amadeus airline reservation system which went down for more than two hours in 2012.
Amadeus was handling up to 3 million bookings and 1 billion transactions per day at the time. When it crashed, it caused more than 400 Qantas flights to be delayed.

https://www.theguardian.com/technology/2012/jul/02/leap-second-amadeus-qantas-reddit

[multiweb]

I had no idea time keeping was so involved. Thanks for sharing Gary :thumbsup:

[gary]

As an update :-


Story here :-
https://www.nature.com/articles/d41586-022-03783-5

With the declaration to stop inserting or removing leap seconds from 2035
or earlier, in essence the problem of the divergence of UTC from UT1 has
been put off to the future to deal with.

It's not the first time in the world's history that a disruption in timekeeping
standards has caused chaos.

Consider the month September 1752 :-

September 1752
Su Mo Tu We Th Fr Sa
1 2 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30


The nearly two weeks missing between the 2nd and 14th were of course because of the switchover to the Gregorian calendar.

Some called out, "Give us back our two weeks". Workers demanded to be paid for the missing days and landlords demanded rent for them.