[time-nuts] Absolute time accuracy pre-Cesium?

Tue Mar 26 19:55:34 UTC 2019

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 both analog and digital
representations, but once we start wondering what the relationship of our
representations are to what time is, we’re in deep philosophical waters.

That said, Western metrology has tended toward emphasizing the usefulness
of uniform units of measure. This has encouraged a trend towards viewing
time as digital. Other cultural traditions view time as analog, and
instead of reckoning time in terms of units of duration, reckon it in
terms of points on a continuum of time. Hence my reference to the Hadith
(the commentaries on the Qur’an).  In the Hadith, it is very important to
identify particular moments when one absolutely may not pray (e.g., the
exact moment of sunrise).  Its techniques for reckoning time are focused
on knowing when particular moments are approaching.

So I guess I’m saying that whether time is analog or digital depends on
culture.  But then again, I’m a cultural anthropologist, so that’s what I
get paid to say.

Best,

Kevin

-- 
Kevin K. Birth, Professor
Department of Anthropology
Queens College, City University of New York
65-30 Kissena Boulevard
Flushing, NY 11367
telephone: 718/997-5518

"Tempus est mundi instabilis motus, rerumque labentium cursus." --Hrabanus
Maurus

"We may live longer but we may be subject to peculiar contagion and
spiritual torpor or illiteracies of the imagination" --Wilson Harris

On 3/26/19, 11:46 AM, "time-nuts on behalf of Bob Albert via time-nuts"
<time-nuts-bounces at lists.febo.com on behalf of time-nuts at lists.febo.com>
wrote:

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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 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 analog measurement?  Or, more fundamentally, is is just a
>concept rather than a reality?
>Bob
>    On Tuesday, March 26, 2019, 7:00:45 AM PDT, Kevin Birth
><Kevin.Birth at qc.cuny.edu> wrote:
>
> 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 achieve accuracy through using multiple clocks.  This technique
>actually seems to have been developed before Brahe with potentates like
>Charles V having large numbers of clocks that he tried to synchronize.
>There is at least one case of a Holy Roman Emperor with a bundle of clocks
>getting angry at a clockmaker for having sold him a poor performing
>clock‹that was Rudolf II.
>
>Before that you have some of the great Islamic observatories that measured
>time with very large instruments.  Here is a link, even without a
>knowledge of Arabic, one can get a sense from the pictures how these
>Muslim astronomers used scale to achieve great accuracy and precision.
>What limited them were their materials‹at a certain scale their
>instruments started to warp under their own weight.  Many of the
>principles in these instruments were based on Ptolemy¹s ALMAGEST, which
>takes things back to the 3rd century AD or so.
>
>Here¹s the link:
>https://gallica.bnf.fr/ark:/12148/btv1b8414999t.r=taqi%20al-din%20instrume
>n
>ts?rk=21459;2
>
>Before that the most detailed account of time measurement equipment is in
>Vitruvius¹ work on architecture, but Vitruvius¹ descriptions are often
>garbled, so there is no good way to judge their accuracy in relationship
>to their claims of precision.
>
>Less well documented are Persian and South Asian methods in which the
>smallest unit translates to something like the duration of a blink of an
>eye.  I do not know enough about those traditions to know what
>observational methods or instruments they used to measure such a unit
>(other than blinking a lot).
>
>Best,
>
>Kevin
>
>
>--
>Kevin K. Birth, Professor
>Department of Anthropology
>Queens College, City University of New York
>65-30 Kissena Boulevard
>Flushing, NY 11367
>telephone: 718/997-5518
>
>"Tempus est mundi instabilis motus, rerumque labentium cursus." --Hrabanus
>Maurus
>
>"We may live longer but we may be subject to peculiar contagion and
>spiritual torpor or illiteracies of the imagination" --Wilson Harris
>
>
>
>
>On 3/26/19, 7:30 AM, "time-nuts on behalf of John Ackermann.  N8UR"
><time-nuts-bounces at lists.febo.com on behalf of jra at febo.com> wrote:
>
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>>
>>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, at 10:03 PM, Ben Bradley
>><ben.pi.bradley at gmail.com> wrote:
>>>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 for its standard. Mechanical clocks were
>>>replaced by more stable electronic quartz crystal oscillators, and
>>>then finally by atomic clocks.
>>>
>>>Perhaps closer to your question: I recall in my readings about
>>>clockmaker John Harrison (likely either in "The Quest for Longitude"
>>>or Dava Sobel's "Longitude") that he would look from the edge of his
>>>window at a particular star each night and note (while counting the
>>>ticks he heard from his clock) the exact moment it would disappear
>>>behind a nearby chimney, and knowing the Earth's rotation takes four
>>>minutes and some (I forget) seconds off from a day, he used this to
>>>calibrate and test the precision and accuracy of his long clocks. It
>>>was suggested he could get within less than second with this method.
>>>This was around age 21, so the year would be about 1714. Looking
>>>online for PZT (photographic zenith tube), I didn't find much about
>>>it, but it was surely first made a couple centuries after this.
>>>
>>>The Sobel book (all about how Harrison won the Longitude prize) is
>>>more a popular book and less technical, but "Quest" has many
>>>mostly-technical articles, mostly about Harrison, as well as beautiful
>>>photos of his clocks. One or two of the articles is by the man who
>>>made (or made the parts for it, the story is complicated) the
>>>one-second-in-100-days "Clock B" pendulum clock, built from Harrison's
>>>writings and claims of just that accuracy in the book he wrote shortly
>>>before his death.
>>>
>>>On Mon, Mar 25, 2019 at 7:00 PM John Ackermann N8UR <jra at febo.com>
>>>wrote:
>>>>
>>>> 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 pre-Atomic.
>>>>
>>>> Thanks!
>>>> John
>>>>
>>>>
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