Thursday, January 08, 2009

Leap second - Just say no.

Over the course of a year solar noon varies by as much as quarter of an hour. From 12:00 (by definition) on midsummer's day and 12:15 around beltane at Greenwich.

'The astronomers' are apparently worried that solar noon must exactly accord with noon according to our clocks everyone else uses because it appears that they don't know how to correct for such things without changing the time table for everyone else. The rotation of the earth is not exact and not exactly predictable.

So what they do instead is they install a leap second once a year or so, giving only six months notice. This messes up no end of computer programs as it means a vast amount of rarely tested code has to be written to deal with the edge cases.

And so there is a US proposal to stop the idiocy and abolish the leap seconds. There is simply no reason to introduce regular corrections of the order of a second to a quantity that varies of its own accord by fifteen minutes over the course of a year. That is three orders of magnitude more than the corrections being made by the astronomers.

Unless you are an astronomer there is no particular reason to care which particular day of the year 12:00 corresponds to solar noon.

So the response of the astronomers to the proposed change is classic agenda denial. 'There is no publicly available documentation that adequately or consistently justifies the proposed re-definition of UTC' In other words we are going to keep meddling with the clocks because we don't know what might happen if we stop doing it.

This is really about power. The astronomers get a feeling of importance from being responsible for proposing their little corrections. They should be told firmly that this is going to stop.

The US should stop piddling around negotiating a change to UTC. Just define a time scale without corrections and announce that that is now official. Job done.

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