[time-nuts] NPR Story I heard this morning

ken hartman ken at hartmans.org
Mon Nov 3 17:52:41 EST 2014

Not to put too fine a point on it, but my practical understanding is that
any two or more clocks generally do *not* agree (that is - yield identical
phase/frequency information) ever, anyway. So atomic horology - and beyond
- means that we continue to ?adjust? ?compensate? clocks of whatever
stability and accuracy to the current, agreed upon "ideal" - even as the
ideal may move or evolve.

On Mon, Nov 3, 2014 at 4:27 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> > I don't see anything in the BIPM definition of the second regarding sea
> level.
> Hi Mike,
> The usual wording for the definition of the SI second also includes the
> word "unperturbed". That little word covers a host of physics and
> engineering effects and can keep graduate students busy for years. You
> either have to eliminate them from your clock or your lab, or extra
> carefully measure then and back-out their effects on your clock's operating
> frequency.
> For a really good example of the sort of corrections that are made inside
> a cesium clock see: http://tf.nist.gov/general/pdf/1497.pdf
> By the time you read to page 30, you'll see table 3 and 4 which summarize
> the perturbing corrections.
> /tvb
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