[time-nuts] Re: leap seconds finally being retired?

[Attila Kinali]

On Tue, 22 Nov 2022 12:21:07 -0600
Chris Caudle via time-nuts <time-nuts at lists.febo.com> wrote:

> Did I miss some messages?  I did not see any discussion of the vote to
> retire leap seconds which took place last Friday.  I just saw this in my
> news headlines today:
> https://gizmodo.com/leap-second-time-1849807606
> 
> "A global group of scientists and government officials voted (almost
> unanimously) Friday to axe the small time adjustment method, in a change
> scheduled to take place by 2035."


"A global group of scientists and government officials" is kind of an
understatement. It was the BIPM CGPM. The BIPM is the super-governmental
organisation that defines our units and that ensures that all countries
use the same definitions. Not to mention their constant effort to ensure
that the realizations of various units are actually within the specified
uncertainty. Globally! The CGPM is the meeting that the BIPM holds every
four years to revise units and coordinate other metrology related tasks.

It is quite an overstatement that we are now going to abolish leap seconds.
While the |UTC - UT1| bound will be revised and made larger than 1s in the
future (until 2035), it does not mean we are going to abolish leap seconds.
Not yet. It's politically a quite difficult topic which will take a lot
of time to resolve.

I.e. until further notice, we will still continue with the leap seconds.

Let us just hope that we don't get a negative leap second until 2035.

> Official resolution (resolution 4):
> https://www.bipm.org/documents/20126/64811223/Resolutions-2022.pdf/281f3160-fc56-3e63-dbf7-77b76500990f
> 
> Also resolution 5 sets out a timeline for redefining the second with
> something other than cesium (would like to have the choice for the
> preferred atom species decided in 2026, and vote on the new standard
> definition in 2030).

This has been ongoing for almost a decade. There was a presentation
at IFCS this April by Noel Dimarq from BIPM/CCTF on the current state
of affairs. There are still quite a few open problems/tasks that need
to be resolved before we can redefine the second. The biggest are that
the frequency accuracy budgets have not been validated yet and that
we do not have any optical atomic clock regularly contributing to TAI yet.

There is also a discussion going on whether we do want a single definition
as we are used to, or whether we want to have an average over multiple
atomic species.

While I think it is possible that we fulfill all the necessary criteria
until 2026 for a redefinition, given how slow things have been moving
in the past years, I am not very confident they will be ready by then.


			Attila Kinali
-- 
The driving force behind research is the question: "Why?"
There are things we don't understand and things we always 
wonder about. And that's why we do research.
		-- Kobayashi Makoto