The only possible references for timekeeping

On 08/10/2015 22:42, Paul Schlyter wrote:

So the major problem in using true solar time to measure how long it
takes small amounts of salt to dissolves inte water would be to fina a
sundial where you could read the time to an accuracy of a fraction of a
second.

That poses an interesting question as to the most accurate possible
practical sundial. I can envisage a large scale one that relied on you
estimating the median position of the shadow or more likely a huge
pinhole based camera obscura. But my back of the envelope calculations
suggest that you would struggle to resolve the position of the sun
beyond about 10^-4 ie 20" arc by eye corresponding to about 10s.

Ultimately limited by faintness of the image and edge turbulence.

--
Regards,
Martin Brown

On Thu, 8 Oct 2015 22:54:38 -0700 (PDT), Quadibloc
wrote:
On Thursday, October 8, 2015 at 11:03:07 PM UTC-6, Paul Schlyter
wrote:

Any clocks contain s two parts:

1. Something that oscillates. E.g. the Sun in our sky, a spring,
a
pendulum, a quartz crystal, an atom.

2. Something that counts the oscillations. E.g. people counting
sunrises, sunsets or transits, mechanical gears, electronic
counters.

The stability of the clocks depends on the stability of the
oscillatior. The rotating Earth is no longer our best available
oscillator.

Note that atomic clocks aren't really clocks in most cases;
instead, they're
frequency sources - used to calibrate associated quartz crystal
clocks that
tell time, if that functionality is desired (i.e. for broadcasting
the WWV time
signal).

A frequency source is an oscillator. To get time from a stable
frequency source the cycles must be counted in some way, directly or
indirectly.

On Fri, 9 Oct 2015 08:30:00 +0100, Martin Brown
wrote:
Depends what you mean by atomic clock. The ones sold to consumers
are
merely picking up broadcast time signals that are derived from the
ensemble of atomic clocks used to maintain true clock time.

They are not atomic clocks, they are radio controlled clocks. These
clocks have no idea what time source the transmitter of the time
signal uses - in principle it could be a sundial.

Empiricists have convinced themselves they are discussing time but they are really only floundering around with timekeeping in their attempt to give clocks priority over the dynamics of the planet which supply the sense of time through the passage of a day , a year or a collection of years.

It must be the saddest spectacle to see grown adults disavow their own experiences to maintain a conviction which includes the idea of more rotations than sunrises/sunsets within a year.

The Equation of Time contains the information of dual surface rotations to the Sun responsible for variations from one noon cycle to the next insofar as the variable orbital speed of the Earth impacts the annual surface rotation,a rotation responsible for the polar day/night cycle and the seasons where it meshes with the daily rotational cycle.

On Thursday, October 8, 2015 at 10:29:47 PM UTC+1, Martin Brown wrote:
On 08/10/2015 18:09, Chris L Peterson wrote:

That said, when the EoT is changing at its fastest, it varies by about
20 seconds per day. That's 231 microseconds per second. So the
dissolution time of a grain of salt could be in error by a few
milliseconds if you chose to use the Earth's rotation as a time
standard. Certainly, there are truly mechanical clocks (that is, gears
and springs) capable of such resolution.

Sunrise to sunrise and sunset to sunset varies a lot more day by day if
you are not close to the equator.

--
Regards,
Martin Brown


Empiricists have always been lost when it comes to the natural inequality observed for each individual passing of the Sun across the observer's meridian at noon as this man demonstrates.

The variations in time from the appearance of the Sun and its disappearance beyond the local horizon across different latitudes in either hemisphere has no bearing on the timekeeping EoT facility. The total length of the natural day which varies is a global event and the same for all latitudes as long as the Sun comes into view each day.

Huygens,even though there is a crucial error in his system, uses sunrise and sunset as a centering observation for locating the midpoint of the natural day for the purpose of applying the correction -

" In the morning then, when the Sun is just half above the Horizon, note, what hour, min. and sec. the Watch points at, if it be going; if not, set it a going, and put the Indexes, at what hour, min. and sec. you please. Let them goe till Sun-set, and when the Body of the Sun is just half under the Horizon, see, what hour, min. and sec. the Indexes of the Watch point at, and note them too; and reckon, how many houres &c. are Pass'd by the Watch between the one and the other: which is done by adding to the Evening-Observation the hours, &c. that the morning-Observation wanted of 12. or 24. in case the Hour-hand hath in the mean time pass'd that hour once or twice; otherwise the difference only gives the time. Then take the half of that number, and add it to the hours, &c. of the morning-Observation, and you shall have the hours, &c. which the Watch did show, when the Sun was in the South; whereunto add the Aequation in the Table belonging to that day, and note the summe. Then some days being pass'd (the more the better) you are to doe Iust the same: And if the hour of the last day be the same, that was noted before, your Watch is well adjusted; but if it be more or less, the difference divided by the number, elapsed between the two Observations, will give the daily difference. And if you will, you may let it rest there, or otherwise, removing the lesser weight of the Pendulum you may adjust it better." Huygens

http://adcs.home.xs4all.nl/Huygens/06/kort-E.html

Empiricists can stand the notion that Newton's 'absolute/ relative time' is nothing more than the timekeeping facility even when he describes it in context of Huygen's use of it in terms of the pendulum clock -

"Absolute time, in astronomy, is distinguished from relative, by the equation of time. For the natural days are truly unequal, though they are commonly considered as equal and used for a measure of time; astronomers correct this inequality for their more accurate deducing of the celestial motions.The necessity of which equation, for determining the times of a phænomenon, is evinced as well from the experiments of the pendulum clock, as by eclipses of the satellites of Jupiter." Newton

If the situation was half way normal it would be easy enough to explain in a straightforward way the technical and historical details surrounding timekeeping and planetary dynamics but nothing is even close to normal at the moment.

On 09/10/2015 08:43, Paul Schlyter wrote:
On Fri, 9 Oct 2015 08:30:00 +0100, Martin Brown
wrote:
Depends what you mean by atomic clock. The ones sold to consumers
are
merely picking up broadcast time signals that are derived from the
ensemble of atomic clocks used to maintain true clock time.

They are not atomic clocks, they are radio controlled clocks. These
clocks have no idea what time source the transmitter of the time signal
uses - in principle it could be a sundial.

They are however sold to consumers as "atomic clocks" (surprisingly).

--
Regards,
Martin Brown

On Friday, October 9, 2015 at 1:07:48 AM UTC-6, oriel36 wrote:

Clocks have no foundation other than the dynamics of the Earth

That is just wrong.

The dynamics of the Earth certainly have a connection to the units we choose
for measuring time. Since we regulate our lives by its day/night cycle, and
since we plant crops by the seasons, the second was an aliquot part of the
average solar day, and our calendar is based on the length of the tropical year.

But telling the time of day isn't the only use for a clock.

Some clocks are stopwatches. And some wris****ches are chronographs.

They're used, for example, to find out how long it took someone to run 100
metres.

A timekeeping device of sorts is used to check that a record turntable moves at
a constant 33 1/3 RPM, and others are used to check the performance of car
engines or jet engines.

For purposes like that, the size of the unit of time, as long as it's not too
large or too small for the purpose at hand, is immaterial. One could define the
fundamental unit of time as being the period of a pendulum that is exactly one
foot long - or as exactly 10,000,000,000 cesium-133 oscillations, instead of
9,192,631,770 of them.

Defining the second as 9,192,631,770 periods of the radio energy emitted by a
particular transition of electron states in the cesium atom lets us state the
laws of physics in a consistent and simple manner. And it lets us find out that
the Earth's rotation is slowing down a tiny little bit (since the length of the
second was chosen to match that of Ephemeris Time) - which is a fact of nature,
not a pretension.

The Earth is a physical object; the Moon is held in orbit about it by its
gravity; and it transfers angular momentum to the Moon. Those facts you inveigh
against as "empiricsm" and "ballistics". But if you think the planets move
because angels push them, instead of by natural physical processes, what need
to you have of the Copernican theory?

John Savard

There is some truth to the saying that something that is too big to fail shouldn't exist in the first place and this certainly applies to academic empiricism and the area surrounding timekeeping and where it dovetails with the cyclical dynamics of this planet. In the broadest sense it covers the entire education system and how students encounter astronomical principles ranging from the framework where events are predicted within the calendar system to the component parts of planetary motions,solar system structure and especially cause and effects between planetary motions and terrestrial sciences.

It is quite an experience to explain the Equation of Time as a timekeeping facility to people who have made careers and livings from promoting Newton's phrasing of it as absolute/relative time and on to the voodoo of the early 20th century.

On Fri, 9 Oct 2015 10:44:05 +0100, Martin Brown
wrote:
On 09/10/2015 08:43, Paul Schlyter wrote:
On Fri, 9 Oct 2015 08:30:00 +0100, Martin Brown
wrote:
Depends what you mean by atomic clock. The ones sold to consumers
are
merely picking up broadcast time signals that are derived from
the
ensemble of atomic clocks used to maintain true clock time.

They are not atomic clocks, they are radio controlled clocks.
These
clocks have no idea what time source the transmitter of the time
signal
uses - in principle it could be a sundial.

They are however sold to consumers as "atomic clocks"
(surprisingly).

I've never seen that. I've only seen them sold as radio controlled
clocks.

On 09/10/2015 21:54, Paul Schlyter wrote:
On Fri, 9 Oct 2015 10:44:05 +0100, Martin Brown
wrote:
On 09/10/2015 08:43, Paul Schlyter wrote:
On Fri, 9 Oct 2015 08:30:00 +0100, Martin Brown
wrote:
Depends what you mean by atomic clock. The ones sold to consumers
are
merely picking up broadcast time signals that are derived from
the
ensemble of atomic clocks used to maintain true clock time.

They are not atomic clocks, they are radio controlled clocks.
These
clocks have no idea what time source the transmitter of the time
signal
uses - in principle it could be a sundial.

They are however sold to consumers as "atomic clocks"
(surprisingly).

I've never seen that. I've only seen them sold as radio controlled clocks.

Maybe Swedish is more precise. Its about 50:50 for headline description
in the UK as is the split between using MSF 60kHz and DCF 77KHz for
actual time signals. GPS receiver based kit is very rare.

German discounters Adli & LIDL have tipped the scales in favour of DCF.
Amazingly the German ones work fine even in North Yorkshire where I
live. It is a minor irritation after changing the battery trying to
remember how to tell it countrycode is UK and not continental time.

--
Regards,
Martin Brown