[LEAPSECS] My FOSDEM slides

[Brooks Harris]

On 2015-03-04 02:12 AM, michael.deckers via LEAPSECS wrote:
>
>    On 2015-03-03 21:05, Martin Burnicki wrote about
>    negative leap seconds:
>
>>  In the 7 year interval where no leap second was required/scheduled I 
>> heard
>>  several people saying we might have needed a negative leap second.
>
>    Fortunately, this is not a matter of speculation. An easy way to
>    see the trend of UT1 - UTC is to look at DUT1 (published in
>    Bulletin D). DUT1 is an approximation to UT1 - UTC and has
>    always stepped down (except, of course, at positive leap seconds),
>    ever since the earliest Bulletin D available on the web (1991-06-20).
>
>    Before a negative leap seconds would be scheduled, we would see
>    DUT1 stepping up several times in a row, so there _is_ some
>    advance warning.
>
We can't predict the future. It's fascinating to read about the many 
factors affecting Earth's rotation. It seems the largest one is the one 
we know least about - the Earth's core. I wonder what DUT1 would have 
looked like around the time of the Chicxulub impactor.

Negative Leap Seconds have been a feature of the specification since the 
beginning. It gives a little more margin to accommodate the unknown, and 
it's not an onerous complication. I hope we concentrate on helping get 
implementations to conform to the UTC specs as they stand rather than 
look for justifications to over simplify the problem.

-Brooks

> Michael Deckers.
>
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