Past/Future leap seconds possibly now predictable?

[2552]

http://arxiv.org/abs/0911.2087

The physical origin of the leap second is discussed in terms of the new gravity model. The calculated time shift of the earth rotation around the sun for one year amounts to $\displaystyle{\Delta T \simeq 0.621 s/ year}$. According to the data, the leap second correction for one year corresponds to $\Delta T \simeq 0.63 \pm 0.03 s/ year $, which is in perfect agreement with the prediction. This shows that the leap second is not originated from the rotation of the earth in its own axis. Instead, it is the same physics as the Mercury perihelion shift. We propose a novel dating method (Leap Second Dating) which enables to determine the construction date of some archaeological objects such as Stonehenge.

 

[tblaxland]

What a load of codswallop!

For starters, we have leap seconds because a second of time measured using the timescale UT1 (as defined by the measured rotation of the Earth) is not the same length as the SI second (which is defined by the atomic behaviour of a Cesium 133 atom and is used for keeping the UT and TT timescales).

If the Earth's angular velocity were constant, UT1 and UT/TT would diverge at a constant rate similar to that predicted by that article, and leap seconds would be introduced at regular intervals. The Earth's angular velocity varies significantly* (up and down) and as such the rate of divergence of of UT1 against UT/TT also varies:

This is also easily shown by the fact that leap seconds have been introduced at a lower rate in recent years than they have in earlier years:

Also, the Earth's rotation is measured against the ICRS, which is a much more stable reference frame than the Sun.

Lastly, "Leap Second Dating" is the most ridiculous idea I have ever heard of. If some artifact was constructed to be aligned with the Sun/Moon at dawn (for example), the number of leap seconds would only effect the sunrise time in terms of when it would occur when measured against today's timescales. The Sun/Moon would still move through the same position in the sky when measured relative to the surface of the Earth, just some minutes earlier than if you made no correction for leap seconds. The effects of plate tectonics, Earth axis precession, subsidence, etc, would be the things that would have an effect on the alignment of some historical artifacts to the Sun/Moon.

I suggest spending some time over at the IERS, for the straight dope on Earth rotation: http://www.iers.org/MainDisp.csl?pid=9-83.

* Why the Earth's period really varies (from IERS):

The variability of the earth-rotation vector relative to the body of the planet or in inertial space is caused by the gravitational torque exerted by the Moon, Sun and planets, displacements of matter in different parts of the planet and other excitation mechanisms. The observed oscillations can be interpreted in terms of mantle elasticity, earth flattening, structure and properties of the core-mantle boundary, rheology of the core, underground water, oceanic variability, and atmospheric variability on time scales of weather or climate.