F-ckin Leap Seconds, how do they work?

Tue Jul 3 23:02:29 UTC 2012

On 7/3/2012 2:35 PM, Tony Finch wrote:
> Peter Lothberg <roll at Stupi.SE> wrote:
>>
>> As the definition of a atomic second is 9192631770 complete
>> oscillations of cesium 133 between enery level 3 and 4, "everyone" can
>> make a second in their lab, that's TAI.
>
> No, TAI isn't based on the SI second you realise in your lab. It's the SI
> second realised on the geoid by a large fleet of clocks.

I think if anyone here is well aware of that that's be Peter:)

The reason for the fleet of clocks is partly political, partly practical 
(cesium clocks are not the most precise... so averaging between a bunch 
of them is used to calibrate better master clocks).  But in theory, if 
you can get the technical wrinkles worked out, you can derive the same 
frequency standard in your lab with a single instrument.

(One more issue is that non-relativistic time is not only the frequency 
of oscillators, but also a reference point).

--vadim