At 03:50 pm 19/01/2006 -0900, Horace wrote: >This has not made it back to me for over 4 hours so here goes again: > >On Jan 19, 2006, at 8:11 AM, Stephen A. Lawrence wrote: >> >> >> The speed of the flights is not a factor, either -- the same time >> lag will be observed no matter how fast they go. However, in order >> to keep the precision with which one needs to keep time down to >> something manageable, it's important to go quickly. If you used a >> ship and retraced Magellan's route instead of using an airplane, >> for instance, the tiny difference in the readings would be totally >> lost in the accumulated inaccuracy of the clocks over a period of >> several months. >>
>Interesting about the speed independence. I think one has to be careful what one means by speed independence here. In it's rotation the earth (and clocks on its surface) is moving in relation to the Beta-atmosphere which reduces the speed of the caesium clock. If you go towards the setting sun then it is not that the clock will speed up. It is that the slow running will be reduced to a minumum when the speed is stationary in relation to the local B-atm. Going round towards the rising sun slow running will be increased. But the difference in speed between planes and ships is small compared to light speed. If one projected a caesium clock at close to the speed of light relative to the absolute frame of reference for motion then its speed would slow right down since mass is the reciprocal of internal closed path velocity (see IHM note on Beta-atm.Yahoo site). The fact that the caesium clocks rate can be altered merely by flying it around the globe shows the utter insanity of using it to define length. If you do, then you end up with the ludicrous result that the distance around the globe clockwise is different from that around the globe widdershins. Frank Grimer
