>>As was noted by someone I believe it was Hilmar, the earth is slowing down. However to compensate for this we agree internationally to redefine the definition of the second. This sometimes occurs each year and sometimes there is no change. Our instrumentation and ability to measure constantly improves. Mathematically, someday the earth will stop rotating and then…
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>I have to question this one Tom, I thought that the second was an agreed constant, it is the length of the year which is corrected by introduction of leap seconds up to 2 times a year.
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>http://www.wikipedia.org/wiki/Atomic_clock
>http://www.sciencemuseum.org.uk/collections/exhiblets/atomclock/essen.asp

Len;

I think my second to the last sentence is relevant as it has been ten years since I worked in the field of Metrology. Thank you for the link. Some great improvements have been made. When I worked in this field we would make adjustments at the end of December, but not every year. Now they make adjustments twice a year.

I worked very closely with Hewlett Packard with their Cesium Clocks and the men who developed them, as well as Trimble Navigation, who did some outstanding work with GPS Receivers. An HP engineer developed a GPS receiver sometime around 1980 and was a good friend of the Metrology Engineer at HP whom I knew.

The engineer was told his receiver would not go into production. So he went to Trimble Navigation (three people at that time) and talked to the owner. He quit HP and went to work for Trimble and HP gave him all rights to the product. I would visit him several times a week and he would show me his progress. We were a couple of engineering types (you think computer programmers are geeks?) and I enjoyed watching this black box become a large corporation in Silicon Valley.

We had a joke during the Gulf War. American troops had Trimble Navigation GPS hand held devices to define where they were within a few meters. (That is a fact) Iraqui soldiers had a piece of sand paper for a map. (I am unable to verify that)

Tom