Subject: Re: [time-nuts] Absolute time accuracy pre-Cesium?
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I have been pondering something somewhat related to all of this.
We know that the smallest unit of a substance is a mo
Hi
TIme is “just a number”, it has no inherent granularity. If you need to measure
at the 10^-?? level,
the units will not be the problem. Coming up with a device that provides 10^-15
or 10^-18 sort of
stability (let alone accuracy …. yikes ….) would take a pretty big limit on
your charge
Read Book IV of Aristotle’s PHYSICS, take two aspirin then use all the
instructions in the Islamic Hadith to know when it is really morning in
order to call me in the morning :)
Aristotle worried a lot about whether the measurement of time is conflated
with time itself. We can reckon time using
: Tuesday, March 26, 2019 8:46 AM
Subject: Re: [time-nuts] Absolute time accuracy pre-Cesium?
> I have been pondering something somewhat related to all of this.
> We know that the smallest unit of a substance is a molecule. The smallest
> unit of charge is maybe an electron. So what coul
I have been pondering something somewhat related to all of this.
We know that the smallest unit of a substance is a molecule. The smallest unit
of charge is maybe an electron. So what could one imagine the smallest unit of
time to be? Is time digital in the nanoscale, or is it always an
Hi John:
One of the papers from 1968 mentioned "continental drift" could be detected if two stations were at the same latitude,
i.e. looking at the same set of stars.
That was also the case for the Latitude Observatories which were all at 39:08. While they were setup with Zenith
Telescopes
It all depends on how far back you want to go. With mechanical
timepieces, even before the pendulum there was Jost Burgi¹s astronomical
clock which achieved a precision of a second, and is reported to have been
accurate to that level based on astronomical measurements. Tycho Brahe
tried to
All -- thanks much for all the great references! I am giving the preso this
afternoon (to a bunch of university space science students) so this will be a
big help. And it looks like there's a lot of great reading for when I have
time to breathe.
Thanks again.
John
On Mar 25, 2019, 10:03 PM,
Hi: I have a some what related question.
I'm just curious how far back in time do the current time scales extend ?
(Ie. When was the first "second hack / synchronization" that can be related
to our current time.)
Thanks in advance for any answers.
Mark Spencer
For independent standards (not quite what you asked) I recall from
"The Science of Clocks and Watches" (a book with much technical info
if you're interested in these mechanical devices) that the most
accurate mechanical/pendulum clock was the Shortt Clock that used a
pendulum in a vacuum chamber
If I am reading the paper correctly they used the moon as the reference. I
would have thought it was the sun. But the moon gives a very clean edge
definition. And now I know how the 770 came about. One more bit in the
knowledge bunker.
Thanks
Paul
WB8TSL
On Mon, Mar 25, 2019 at 8:03 PM Tom Van
On Mon 2019-03-25T16:54:28-0700 Tom Van Baak hath writ:
> In retrospect we would have had fewer leap seconds if they had
> chosen 9192631950 Hz instead of 9192631770 Hz. But at the time it
> wasn't a choice; it was just a measurement.
And it was a measurement which was performed during an
> Does anyone have a pointer to information about the absolute time
> accuracy (not stability) that was available via PZT or other techniques
> prior to the Cesium definition? I'm doing a presentation and want to
> show the evolution of accuracy. My Google-fu has failed me in finding
>
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/FFA10ED6A784AA1E39637CC0CA93B750/S0074180900036007a.pdf/div-class-title-some-advantages-and-disadvantages-of-a-photographic-zenith-tube-div.pdf
indicates a timing error of around 6 millisec
Bruce
> On 26 March 2019 at 12:15
On Mon 2019-03-25T18:44:05-0400 John Ackermann N8UR hath writ:
> Does anyone have a pointer to information about the absolute time accuracy
> (not stability) that was available via PZT or other techniques prior to the
> Cesium definition? I'm doing a presentation and want to show the evolution
>
John
http://adsabs.harvard.edu/full/1968JRASC..62..205T
indicates a timing accuracy of a few milliseconds was typical for the Calgary
PZT.
Bruce
> On 26 March 2019 at 11:44 John Ackermann N8UR wrote:
>
>
> Does anyone have a pointer to information about the absolute time
> accuracy (not
Does anyone have a pointer to information about the absolute time
accuracy (not stability) that was available via PZT or other techniques
prior to the Cesium definition? I'm doing a presentation and want to
show the evolution of accuracy. My Google-fu has failed me in finding
anything
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