[LEAPSECS] Nit-pick: SI second

Paul Sheer p at 2038bug.com
Wed Feb 9 18:58:51 EST 2011

Since the velocity of the atomic clock causes relativistic dilation,
surely it is not the altitude-above-sea-level, but the radial distance
from the earths axis that we are talking about???

I.e. surely both latitude and altitude affect the ceasium? I mean the
velocity of the atomic clock as it stands in the lab is dictated by the
earth rotation times the radial distance from the earths rotational



On Thu, 2011-02-10 at 00:24 +0100, Magnus Danielson wrote:

> On 07/02/11 20:10, Tom Van Baak wrote:

> >> It is also why TAI's rate was adjusted in the 1990's to compensate for

> >> the red-shifted data that had been collected at NIST in Boulder, since

> >> it sits at about 5400' (1700m) above sea level (as well as other

> >> facilities not at sea level).

> >>

> >> Warner

> >

> > Are you sure you aren't confusing red shift (which has been

> > a known factor since the 60's) with blackbody shift (which

> > only arose in the 90's as clocks hit the 1e-15 level)?


> These are distinct in the face of SI. The nit-picker could find all the

> material needed in


> http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf


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