In article ,
John Sager wrote:

Day length is already increasing due to the transfer of angular momentum
to the moon via tides, and there will be a smaller exchange with the sun.
In principle you should be able to model this, but there are also
changes to the earth's moment of inertia which affect angular velocity,
and these seem to be quite unpredictable - who would have thought
before the fact that we wouldn't need leap seconds for the past
5 years, given the previous insertion rate?

Quite.

What I was (and am) looking for is some bounds, not necessarily
down to the last second. I have received some very useful pointers,
and will be studying them - which will continue my education, if
nothing else :-)

To put this in perspective, the accuracy of times is very roughly
proportional to the distance from the present. Beyond about a few
hundred years, measuring to seconds is meaningless. By the stage
we get back to the Carboniferous, exact year counts are amusing
but not science ....


Regards,
Nick Maclaren.