> If the SI second were properly tuned to the mean solar day, and the
> secular slowing were eliminated, there would be no need to mess about with
> the civil time scale, because the random accelerations and decelerations
> would cancel out in the long run. Of course, we'd have to tolerate larger
Rob Seaman scripsit:
> Third result - even in the absence of lunar braking, leap jumps
> (or equivalent clock adjustments) would remain necessary.
Why is that?
If the SI second were properly tuned to the mean solar day, and the
secular slowing were eliminated, there would be no need to mess abou
Tom Van Baak says:
you could say the SI second was defined
a bit too fast. The error bars on Essen's 9192631770 Hz
cesium calibration were rather large and he used an old
epoch for the ET second.
Hmmm - I see a gedankenexperiment here. (Maybe I'll
judge that category of science fair project s
> > In fact, leap seconds are simply due to the earth
> > being slow. How it got to be "slow" and whether
> > it is "slowing" are another issue.
>
> Let me see if I have this right:
>
> 1) We have leap seconds because the Earth rotates more slowly
> than once every 86,400 SI seconds.
Yes. (and I k
John Cowan wrote:
I accidentally specified sidereal rather than mean solar days by
using the wording "the Earth rotates".
"Rotate" is as perfectly good a word to use relative to our nearby star
as to the distant ones :-) The solar system is chock full of nifty
synodic
periodicities and resona
Rob Seaman scripsit:
> Blame for what? I'm left wondering. Are we now fretting about
> the distinction between sidereal and solar time again?
I accidentally specified sidereal rather than mean solar days by
using the wording "the Earth rotates".
> A leap hour is just 3600 embargoed leap second
John Cowan accepts the blame:
1) We have leap seconds because the SI second is shorter
than 1/86,400 of a mean solar day.
Post in haste, repent at leisure (I've been going with too little
sleep lately, for reasons unknown...) I actually do know that
the earth rotates in less than 1 mean sola
Rob Seaman scripsit:
> >1) We have leap seconds because the SI second is shorter
> >than 1/86,400 of a mean solar day.
*facepalm*
Post in haste, repent at leisure (I've been going with too little
sleep lately, for reasons unknown...) I actually do know that
the earth rotates in less than 1 mean
John Cowan wrote:
1) We have leap seconds because the Earth rotates more slowly
than once every 86,400 SI seconds.
2) Leap seconds will become more frequent in the future because
the Earth is decelerating.
3) Leap seconds occur irregularly because the Earth's deceleration
is not constant and i
Hi Tom,Careful not to confuse rate with acceleration andpropagate a common misconception that leapseconds are due to an acceleration/decelerationeffect (as in "leap seconds are due to the earthslowing down").In fact, leap seconds are simply due to the earthbeing slow. How it got to be "slow" and wh
Tom Van Baak scripsit:
> In fact, leap seconds are simply due to the earth
> being slow. How it got to be "slow" and whether
> it is "slowing" are another issue.
Let me see if I have this right:
1) We have leap seconds because the Earth rotates more slowly
than once every 86,400 SI seconds.
2)
> To the extent that I understand the point you are
> aiming for, this statement conflates two issues:
>
> 1) that the long term secular deceleration is only
> perceptible as a baseline trend hidden beneath
> large amplitude, short period, effects, and
>
> 2) that leap seconds aren't the result of
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