On Thu 2011/02/10 21:31:32 -0800, "Tom Van Baak" wrote in a message to: "Leap Second Discussion List" <leapsecs@leapsecond.com>
>> A clock at the equator has a tangential velocity of 500m/s >> whereas for one at the pole it is 0m/s. The difference, >> amounts to about 100ns/day as per your later calculations. >> This is the Sagnac effect of Special Relativity. > >Something's wrong here. The Sagnac effect as applied to >clock synchronization is a time offset (a function of path >and direction), not a rate (frequency offset). Its maximum Consults references - yes, seems I was mistaken about it being the Sagnac effect. >Something else is wrong here too. National UTC timing labs >are all over the world, at a variety of latitudes and altitudes. >No one corrects for latitude as far as I know; only altitude. >So I can't see why pole vs. equator would have anything to >do with the SI second. Correcting only for elevation above >the geoid I fully expect a cesium standard to keep the same >time in Fairbanks as it would in Boulder or Paris, etc. Am I >missing something? Should I start planning a new clock trip? I can't see how they could ignore latitude. See Example 2 of http://en.wikipedia.org/wiki/Proper_time as well as Rob's references. I think someone already mentioned that GPS satellites correct for time dilation, though their orbital velocities make for a much larger correction. Regards, Mark Calabretta _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
