Portable general timestamp format, not 2038-limited

Martin Gregorie martin at see.sig.for.address
Tue Jun 26 22:21:01 CEST 2007


sla29970 at gmail.com wrote:
> On Jun 25, 6:46 pm, Paul Rubin <http://phr...@NOSPAM.invalid> wrote:
>> TAI really does seem like the most absolute--if you are a user in
>> orbit or on Mars, then UTC timestamps will seem pretty meaningless and
>> artificial.
> 
> TAI makes sense for clocks on the surface of the earth (at least until
> ion trap clocks and picosecond intercomparison become routine, at
> which point not even TAI tells what time it is for you), but clocks
> off the surface of the earth tick at rates which already differ
> nonlinearly from TAI by measurable amounts.
> 
True. The first direct demonstration of relativistic time dilation was 
made in 1971 with three HP cesium beam atomic clocks. One stayed in the 
lab, while the other were shipped round the world in opposite directions 
  on commercial jet flights. When the clocks were compared afterwards 
the errors in the traveling clocks agreed with theory within 
experimental error. See:

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html

for more detail. This shows the clocks don't have to be moving at 
interplanetary speeds to be significantly affected.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |



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