Re: [time-nuts] The forbidden question

[jimlux]

On 6/4/19 3:21 PM, Poul-Henning Kamp wrote:


In message 
, "William H. Fite" writes:


What I am asking is not the validity of the quest for better timing
but rather its tangible applications.


Tangible for who ?

For the average pedestrian there are no *current* tangible applications
where cesium level time-keeping isn't plenty.

However, the same would have been said about chronometers and quartz
clocks at various times in the past.

To answer your question we would need to look about 20-30 years
into the future, which seems to be the median time for better
timekeeping to break through to the wider public, even if they do
not know it has happened, (ie: longitude navigation, digital telephone
networks, GPS.

Peeking 20-30 years into the future is an unsolved problem, so I
would argue that your question is unanswerable at this time.

30 odd years ago, I heard a speech from a guy at AT who said that by 
definition, you cannot predict technology that will result in a 
revolution ahead of time.


He was commenting on the incredibly rapid drop in transoceanic 
communication costs (and in networking costs in general). He said that 
nobody in the 1950s or 1960s could have *accurately* forecast what 
having 100 Mbps to the desktop would mean. At the time he said this 
(1993), the cost of a "voice call" worth of bandwidth (50-60kbps) across 
the ocean was a few dollars (capital and some amount of operating cost) 
- he said that was totally disruptive to an industry that based its 
entire pricing model on dollars per (miles*minutes). The cost of a voice 
channel in an optical fiber was literally "too cheap to meter".


He also commented that when electric motors came out, nobody could have 
predicted how pervasive they would be.  The replaced steam engines, 
water wheels, and animal treadmills in applications like power looms, 
machine shops (think common shaft with all those belt driven machine 
tools).  Later, appliances used to advertise "contains an electric 
motor" (imagine a washing machine that you had to manually actuate with 
foot pedals and a crank for the wringer - or a sewing machine.. my 
grandmother had a sewing machine that had both a foot treadle and a 
retrofitted electric motor).


Now, the average car has dozens of motors in it, and nobody even 
mentions it, nor advertises it "The new sports car, now with 72 motors". 
 Heck, in my car, the rear view mirror has 3 motors, and there's 3 
mirrors. And how many motors in the seats, and the HVAC, and actuating 
various and sundry other things.



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Re: [time-nuts] The forbidden question

[jimlux]

On 6/4/19 3:05 PM, Hal Murray wrote:



Are we developing these incredible devices just to push boundaries? Or do
they have some practical purpose?


I don't know of any current projects that need a significantly better clock,
but that's the sort of thing that wouldn't get a lot of publicity - just some
hand-waving discussions.  "What if we could ..."


If you want some ideas to BS about...

You might ask the radio astronomers what they would do with a better clock.


navigation of spacecraft and making better gravity measurements of 
planets and moons.



One of the "pushing the frontiers of clocks" things is that stuff that 
starts in the lab eventually winds up portable. Sure, there's no cesium 
fountain clocks in space (that I'm aware of), but we are doing trapped 
mercury ion clocks (Deep Space Atomic Clock) and chip scale atomic 
clocks (CSAC), both of which fundamentally enable new stuff.


Navigation of spacecraft today is done by precisely measuring the round 
trip time of a signal to the spacecraft and back.  This is great if you 
want to know the position and velocity of the spacecraft *on the ground*.


However, what if the spacecraft needs to know where it is, by itself - 
so it can autonomously navigate. For that, what you need is a good clock 
on the ground, to transmit precisely timed signals (with appropriate 
additional information), and the spacecraft receives them, with a very 
good clock, and figures out where it is.


You might receive these signals at different times, so you need a nice 
stable clock on board to be able to compare time signals received at 
time T1 to signals received at time T2, some hours or days later.


One Way Nav is a *big deal* for enabling spacecraft autonomy, 
particularly with multiple spacecraft constellations.









What would the radio guys do with better clocks?  I'll bet you can dig deeper
into the noise when trying to find a spread spectrum signal.

It would be interesting to look at the history of similar advances.  Cesium
clocks are now in widespread use.  Rubidium clocks are a spinoff.  Were any of
the common uses anticipated back when people were struggling to build the
initial atomic clocks?  How much of the engineering associated with atomic
clocks was uncovered by the early researchers?




A lot...


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Re: [time-nuts] BG7TBL 10 MHz OCXO

[Bob kb8tq]

Hi

G sensitivity in quartz crystals is a pretty well documented sort of thing. For 
an AT cut numbers in the 1 to 2 ppb per G are
not uncommon. For SC’s the numbers may be a bit lower than that. It simply has 
to do with the stress / strain properties of
the quartz and how they impact the resonant frequency.

So no, you can’t duplicate it directly with an electromagnetic field. You can 
indeed tune an SC with voltage on the electrodes.
Not so much with an AT.

Bob

> On Jun 4, 2019, at 6:32 PM, Glenn Little WB4UIV  
> wrote:
> 
> Can the shift be duplicated by an electromagnetic field?
> If so this may be a was to fine tune an oscillator.
> 
> Glenn
> 
> On 6/3/2019 6:29 PM, Adrian Godwin wrote:
>> On Mon, Jun 3, 2019 at 11:01 PM Andy Backus  wrote:
>> 
>>>   2.  interesting observation: turning the unit 90 degrees onto its right
>>> hand side immediately increases the output frequency by 10 mHz
>>> (reversible); turning the unit 90 degrees onto its left end immediately
>>> decreases the output frequency by 10 mHz (also reversible)
>>> 
>>> 
>> This is quite normal.
>> 
>> https://www.youtube.com/watch?v=zILwgQhjC_Q
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>> 
> 
> -- 
> ---
> Glenn LittleARRL Technical Specialist   QCWA  LM 28417
> Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
> QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
> "It is not the class of license that the Amateur holds but the class
> of the Amateur that holds the license"
> 
> 
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Re: [time-nuts] The forbidden question

[Dana Whitlow]

In answer to the question about radio astronomers, consider VLBI (Very Long
Baseline Interferometry).

VLBI is a mapping (imaging) process in which signals are *simultaneously*
received from
a small sky region of interest by a collection of radio telescopes
scattered about the world.
In order for the process to work, ultimately it is necessary for all the
signals to be lined up
in time (think phase) to a small fraction of a period of the microwave
frequency being used.
Suppose the frequency is around 5 GHz, then the period is just 200 psec,
and a small
enough fraction thereof is maybe 10 psec or less.

Now present day clocks and time transfer schemes are not good enough to
accomplish
that feat "open loop" across a collection of observatories spanning
thousands of miles.
Fortunately, radio astronomers have developed a set of magical techniques
collectively
called "self calibration" by which, with extreme care, the job can still be
done provided
that the data sets from each observatory are initially lined up to within
around 100 nsec.

However, another requirement is that the LOs for the different
observatories' receivers maintain
that constant phase relationship I mentioned above during the course of an
observation.  In
practice this condition can typically only be held for a few minutes at a
time, and the only
atomic clock in commercial production that can do that is the hydrogen
maser.  Cs beam
clocks are simply not stable enough in that time frame to get the job
done.  But I'm quite sure
that much more stable clocks yet would relieve the overall problem of
making much longer
continuous observations.  Not solve all aspects of the problem by itself,
but it would sure
help.

Another use for such observations is earthbound geodesy, used to track
continental drift
and the like.  Here the preferred radio source is a bright point source
such as a quasar,
and the point is monitoring the position of each observatory.   In this
application it's
important to accurately know the position of the selected source, and one
of the applications
of VLBI is also to measure source locations.  So if you're an
astrophysicist you want to know
the precise locations of all the telescopes, and uncertainty in this is
"noise".  But the person
wanting geodesic information want to measure drift in telescope positions,
and needs to
know where the source is located in the sky.  So one man's signal is the
other man's noise,
and vice versa.  In any case, anything that can be done to improve phase
coherence between
all the receivers in the network can only help.

Dana

Previous "Keeper of The Clock" at the Arecibo Observatory in Puerto Rico

On Tue, Jun 4, 2019 at 6:01 PM Poul-Henning Kamp  wrote:

> 
> In message  7bl...@mail.gmail.com>
> , "William H. Fite" writes:
>
> >What I am asking is not the validity of the quest for better timing
> >but rather its tangible applications.
>
> Tangible for who ?
>
> For the average pedestrian there are no *current* tangible applications
> where cesium level time-keeping isn't plenty.
>
> However, the same would have been said about chronometers and quartz
> clocks at various times in the past.
>
> To answer your question we would need to look about 20-30 years
> into the future, which seems to be the median time for better
> timekeeping to break through to the wider public, even if they do
> not know it has happened, (ie: longitude navigation, digital telephone
> networks, GPS.
>
> Peeking 20-30 years into the future is an unsolved problem, so I
> would argue that your question is unanswerable at this time.
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>
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Re: [time-nuts] The forbidden question

[Will Kimber]

If I can stir the pot a bit.


What other standards are measured to the same degree of accuracy? i.e.
ppb or better.


The thing with TIME is that its measurement is a abstract concept.  Most
other "standards" have a physical representation.


Cheers,

Will

On 5/06/19 10:21 AM, Poul-Henning Kamp wrote:


In message 
, "William H. Fite" writes:


What I am asking is not the validity of the quest for better timing
but rather its tangible applications.

Tangible for who ?

For the average pedestrian there are no *current* tangible applications
where cesium level time-keeping isn't plenty.

However, the same would have been said about chronometers and quartz
clocks at various times in the past.

To answer your question we would need to look about 20-30 years
into the future, which seems to be the median time for better
timekeeping to break through to the wider public, even if they do
not know it has happened, (ie: longitude navigation, digital telephone
networks, GPS.

Peeking 20-30 years into the future is an unsolved problem, so I
would argue that your question is unanswerable at this time.



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Re: [time-nuts] BG7TBL 10 MHz OCXO

[Glenn Little WB4UIV]

Can the shift be duplicated by an electromagnetic field?
If so this may be a was to fine tune an oscillator.

Glenn

On 6/3/2019 6:29 PM, Adrian Godwin wrote:

On Mon, Jun 3, 2019 at 11:01 PM Andy Backus  wrote:


   2.  interesting observation: turning the unit 90 degrees onto its right
hand side immediately increases the output frequency by 10 mHz
(reversible); turning the unit 90 degrees onto its left end immediately
decreases the output frequency by 10 mHz (also reversible)



This is quite normal.

https://www.youtube.com/watch?v=zILwgQhjC_Q
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--
---
Glenn LittleARRL Technical Specialist   QCWA  LM 28417
Amateur Callsign:  WB4UIVwb4...@arrl.netAMSAT LM 2178
QTH:  Goose Creek, SC USA (EM92xx)  USSVI LM   NRA LM   SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


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Re: [time-nuts] The forbidden question

[Richard (Rick) Karlquist]

The article cited below gives some examples of what Optical Lattice 
Clocks (OLC) would be useful for:


https://ieeexplore.ieee.org/document/6905489

Rick N6RK

On 6/4/2019 9:43 AM, William H. Fite wrote:


What useful purpose, if any, is served by the continuing evolution of
clocks like NIST-F2 that now achieve accuracy along the lines of one second
per many billions of years? Are there tangible benefits to be had? I
consulted an astronomer friend who advised that the current generation of


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Re: [time-nuts] The forbidden question

[William H. Fite]

That's an excellent point, Bob. We have friends who have friends who are
involved with the long baseline interferometry (LIGO) lab in Louisiana. I
will inquire and, if they have any relevant information I will pass it
along to you.

Thanks for your reply.

On Tuesday, June 4, 2019, Bob kb8tq  wrote:

> Hi
>
> One very basic thing that precision clocks allow you to dig deeper into is
> gravity. A gravity wave passing between two clocks should show up as a
> time
> ripple.
>
> Bob
>
> > On Jun 4, 2019, at 12:43 PM, William H. Fite  wrote:
> >
> > Warning: Potentially heretical material below
> >
> > Let me begin by saying I am neither an engineer nor a time expert. My PhD
> > is in statistics and my spouse's PhD is in theoretical computer science,
> > working on quantum computer algorithms. Neither of us claims any special
> > expertise when it comes to time and frequency measurement. I am a radio
> > amateur and I came to this group following a recommendation from John
> > Ackermann, who very kindly answered some questions for me regarding the
> > amateur radio frequency measurement test. I thoroughly enjoy the dialogue
> > here and I think that I have learned a bit about the subject though, by
> any
> > standard of this group, I am the rankest newbie.
> >
> > My question is a serious one. I am not trolling, nor am I trying to begin
> > an argument, nor am I implying criticism of anyone or any endeavor, here
> or
> > elsewhere.
> >
> > What useful purpose, if any, is served by the continuing evolution of
> > clocks like NIST-F2 that now achieve accuracy along the lines of one
> second
> > per many billions of years? Are there tangible benefits to be had? I
> > consulted an astronomer friend who advised that the current generation of
> > clocks would allow a suitable space vehicle to plant a probe squarely in
> > the middle of Alpha Centauri, if rocket technology existed to do so. We
> > have many friends in the academic computer science community who say that
> > neither conventional nor quantum computers that exist at present or in
> the
> > projectable future require anything like this kind of accuracy.
> >
> > By no means am I questioning the value of new knowledge qua knowledge.
> For
> > theoreticians like the one to whom I am wedded, no justification is
> needed
> > beyond the words of mountaineer George Mallory: "Because it's there." I'm
> > sure that engineers and scientists in the field of time and frequency
> > measurement feel the same. From that perspective, there need be no
> > rationalization beyond the desire to do it just a little better than it
> has
> > been done.
> >
> > Please don't lecture me about the value of science for its own sake. My
> > career has largely been built on that principle. I'd like to be informed
> as
> > to present or anticipated applications that require such accuracy. Are we
> > developing these incredible devices just to push boundaries? Or do they
> > have some practical purpose?
> >
> > I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
> > be deleted unread.
> >
> > Thanks for your help.
> >
> >
> > --
> > Homo sum humani a me nihil alienum puto.
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to http://lists.febo.com/mailman/
> listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
>
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> listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>


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Re: [time-nuts] The forbidden question

[William H. Fite]

I appreciate your point, one that I have emphasized to my graduate students
many times over 30 years of teaching. Of course you are entirely correct.

On Tuesday, June 4, 2019, Kevin Birth  wrote:

> When a clock is represented as only losing a second in billions of years
> that is a statement packaged in a rhetorical fashion to impress readers.
> Another way to think about the statement of such long-term accuracy is
> that it is a improvement in reducing uncertainty about accuracy over time,
> and that includes uncertainty in the short term at high levels of
> precision.
>
> Consider that the SI second is 9,192,631,770 transitions of cesium, but
> that when the number of cesium transitions per second was originally
> measured, there was a plus or minus of 20 transitions.  That means in
> first generation cesium clocks there was a lurking uncertainty in accuracy
> of at least plus or minus 20 not taking into account all the other factors
> that can influence a clock¹s performance.  Now if a clock¹s time was
> uncertain by just a few transitions, then that could produce a 1 second
> loss of accuracy over billions of years.
>
> So one way to look at the claim that a clock is accurate for billions of
> years (although NIST-F2 is claimed for hundreds of millions of years) is
> that it is a clock that has reduced the uncertainty in the short run,
> making it not only precise, but accurate at high levels of precision over
> short periods of time.
>
> Now that we live in a world where big data analysis (including data feeds
> on Wall St) have ns levels of precision, reducing uncertainty in accuracy
> in primary standards is highly valued.


How precise does it need to be?

>
> Or, at least that is how I understand things.


Thanks for your reply.

>
> 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 c/ursus." --Hrabanus


To which I reply:  Tunc temporis omnia consumit omnia iubeo.



> We may live longer but we may be subject to peculiar contagion and
> spiritual torpor or illiteracies of the imagination" --Wilson Harris
>
>
>
>
> On 6/4/19, 12:43 PM, "time-nuts on behalf of William H. Fite"
>  wrote:
>
> >EXTERNAL EMAIL: please report suspicious content to the ITS Help Desk.
> >
> >
> >Warning: Potentially heretical material below
> >
> >Let me begin by saying I am neither an engineer nor a time expert. My PhD
> >is in statistics and my spouse's PhD is in theoretical computer science,
> >working on quantum computer algorithms. Neither of us claims any special
> >expertise when it comes to time and frequency measurement. I am a radio
> >amateur and I came to this group following a recommendation from John
> >Ackermann, who very kindly answered some questions for me regarding the
> >amateur radio frequency measurement test. I thoroughly enjoy the dialogue
> >here and I think that I have learned a bit about the subject though, by
> >any
> >standard of this group, I am the rankest newbie.
> >
> >My question is a serious one. I am not trolling, nor am I trying to begin
> >an argument, nor am I implying criticism of anyone or any endeavor, here
> >or
> >elsewhere.
> >
> >What useful purpose, if any, is served by the continuing evolution of
> >clocks like NIST-F2 that now achieve accuracy along the lines of one
> >second
> >per many billions of years? Are there tangible benefits to be had? I
> >consulted an astronomer friend who advised that the current generation of
> >clocks would allow a suitable space vehicle to plant a probe squarely in
> >the middle of Alpha Centauri, if rocket technology existed to do so. We
> >have many friends in the academic computer science community who say that
> >neither conventional nor quantum computers that exist at present or in the
> >projectable future require anything like this kind of accuracy.
> >
> >By no means am I questioning the value of new knowledge qua knowledge. For
> >theoreticians like the one to whom I am wedded, no justification is needed
> >beyond the words of mountaineer George Mallory: "Because it's there." I'm
> >sure that engineers and scientists in the field of time and frequency
> >measurement feel the same. From that perspective, there need be no
> >rationalization beyond the desire to do it just a little better than it
> >has
> >been done.
> >
> >Please don't lecture me about the value of science for its own sake. My
> >career has largely been built on that principle. I'd like to be informed
> >as
> >to present or anticipated applications that require such accuracy. Are we
> >developing these incredible devices just to push boundaries? Or do they
> >have some practical purpose?
> >
> >I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
> >be deleted unread.
> >
> >Thanks for your help.
> >
> >
> >--
> >Homo sum humani a me nihil 

Re: [time-nuts] The forbidden question

[Poul-Henning Kamp]

In message 
, "William H. Fite" writes:

>What I am asking is not the validity of the quest for better timing
>but rather its tangible applications.

Tangible for who ?

For the average pedestrian there are no *current* tangible applications
where cesium level time-keeping isn't plenty.

However, the same would have been said about chronometers and quartz
clocks at various times in the past.

To answer your question we would need to look about 20-30 years
into the future, which seems to be the median time for better
timekeeping to break through to the wider public, even if they do
not know it has happened, (ie: longitude navigation, digital telephone
networks, GPS.

Peeking 20-30 years into the future is an unsolved problem, so I
would argue that your question is unanswerable at this time.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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[time-nuts] The forbidden question

[William H. Fite]

In answer to your question, there are practical things that can be done
with an optical or electron microscope that cannot be done with unaided
vision. What I am asking is not the validity of the quest for better timing
but rather its tangible applications. Note that I did not say or even
suggest that there are no tangible applications, I'm simply interested in
what they are. I thought I made that fairly clear.

As to your analogy, it is valid only if and to the extent that NIST-F2 has
practical applications. That is what I am asking about.

No,  there is no logic issue in my statement but I will grant that it is a
bit imprecise. (Donning pedant hat) "...will be deleted as soon as I have
read enough to conclude that it is dismissive or snarky."

If you have an answer to my question, I will be very happy to receive it.

Best regards



On Tuesday, June 4, 2019, Bill Beam  wrote:

> You will have an answer if you can answer the question:
> "Why is an optical microscope needed when unaided vision is good enough?"
> My PhD is in high energy particle physics ca 1966.
> This is not intended to be 'Dismissive and/or snarky'.
> Your statement "Dismissive and/or snarky replies will be deleted unread."
> has a logic issue
> Regards (73)
>
> On Tue, 4 Jun 2019 12:43:04 -0400, William H. Fite wrote:
>
> >Warning: Potentially heretical material below
>
> >Let me begin by saying I am neither an engineer nor a time expert. My PhD
> >is in statistics and my spouse's PhD is in theoretical computer science,
> >working on quantum computer algorithms. Neither of us claims any special
> >expertise when it comes to time and frequency measurement. I am a radio
> >amateur and I came to this group following a recommendation from John
> >Ackermann, who very kindly answered some questions for me regarding the
> >amateur radio frequency measurement test. I thoroughly enjoy the dialogue
> >here and I think that I have learned a bit about the subject though, by
> any
> >standard of this group, I am the rankest newbie.
>
> >My question is a serious one. I am not trolling, nor am I trying to begin
> >an argument, nor am I implying criticism of anyone or any endeavor, here
> or
> >elsewhere.
>
> >What useful purpose, if any, is served by the continuing evolution of
> >clocks like NIST-F2 that now achieve accuracy along the lines of one
> second
> >per many billions of years? Are there tangible benefits to be had? I
> >consulted an astronomer friend who advised that the current generation of
> >clocks would allow a suitable space vehicle to plant a probe squarely in
> >the middle of Alpha Centauri, if rocket technology existed to do so. We
> >have many friends in the academic computer science community who say that
> >neither conventional nor quantum computers that exist at present or in the
> >projectable future require anything like this kind of accuracy.
>
> >By no means am I questioning the value of new knowledge qua knowledge. For
> >theoreticians like the one to whom I am wedded, no justification is needed
> >beyond the words of mountaineer George Mallory: "Because it's there." I'm
> >sure that engineers and scientists in the field of time and frequency
> >measurement feel the same. From that perspective, there need be no
> >rationalization beyond the desire to do it just a little better than it
> has
> >been done.
>
> >Please don't lecture me about the value of science for its own sake. My
> >career has largely been built on that principle. I'd like to be informed
> as
> >to present or anticipated applications that require such accuracy. Are we
> >developing these incredible devices just to push boundaries? Or do they
> >have some practical purpose?
>
> >I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
> >be deleted unread.
>
> >Thanks for your help.
>
>
> >--
> >Homo sum humani a me nihil alienum puto.
> >___
> >time-nuts mailing list -- time-nuts@lists.febo.com
> >To unsubscribe, go to http://lists.febo.com/mailman/
> listinfo/time-nuts_lists.febo.com
> >and follow the instructions there.
>
>
> Bill Beam
> NL7F
>
>
>
>

-- 
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Re: [time-nuts] The forbidden question

[Bill Beam]

You will have an answer if you can answer the question:
"Why is an optical microscope needed when unaided vision is good enough?"
My PhD is in high energy particle physics ca 1966.
This is not intended to be 'Dismissive and/or snarky'.
Your statement "Dismissive and/or snarky replies will be deleted unread." has a 
logic issue
Regards (73)

On Tue, 4 Jun 2019 12:43:04 -0400, William H. Fite wrote:

>Warning: Potentially heretical material below

>Let me begin by saying I am neither an engineer nor a time expert. My PhD
>is in statistics and my spouse's PhD is in theoretical computer science,
>working on quantum computer algorithms. Neither of us claims any special
>expertise when it comes to time and frequency measurement. I am a radio
>amateur and I came to this group following a recommendation from John
>Ackermann, who very kindly answered some questions for me regarding the
>amateur radio frequency measurement test. I thoroughly enjoy the dialogue
>here and I think that I have learned a bit about the subject though, by any
>standard of this group, I am the rankest newbie.

>My question is a serious one. I am not trolling, nor am I trying to begin
>an argument, nor am I implying criticism of anyone or any endeavor, here or
>elsewhere.

>What useful purpose, if any, is served by the continuing evolution of
>clocks like NIST-F2 that now achieve accuracy along the lines of one second
>per many billions of years? Are there tangible benefits to be had? I
>consulted an astronomer friend who advised that the current generation of
>clocks would allow a suitable space vehicle to plant a probe squarely in
>the middle of Alpha Centauri, if rocket technology existed to do so. We
>have many friends in the academic computer science community who say that
>neither conventional nor quantum computers that exist at present or in the
>projectable future require anything like this kind of accuracy.

>By no means am I questioning the value of new knowledge qua knowledge. For
>theoreticians like the one to whom I am wedded, no justification is needed
>beyond the words of mountaineer George Mallory: "Because it's there." I'm
>sure that engineers and scientists in the field of time and frequency
>measurement feel the same. From that perspective, there need be no
>rationalization beyond the desire to do it just a little better than it has
>been done.

>Please don't lecture me about the value of science for its own sake. My
>career has largely been built on that principle. I'd like to be informed as
>to present or anticipated applications that require such accuracy. Are we
>developing these incredible devices just to push boundaries? Or do they
>have some practical purpose?

>I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
>be deleted unread.

>Thanks for your help.


>-- 
>Homo sum humani a me nihil alienum puto.
>___
>time-nuts mailing list -- time-nuts@lists.febo.com
>To unsubscribe, go to 
>http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>and follow the instructions there.


Bill Beam
NL7F




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Re: [time-nuts] The forbidden question

[Bob kb8tq]

Hi

One very basic thing that precision clocks allow you to dig deeper into is
gravity. A gravity wave passing between two clocks should show up as a time 
ripple. 

Bob

> On Jun 4, 2019, at 12:43 PM, William H. Fite  wrote:
> 
> Warning: Potentially heretical material below
> 
> Let me begin by saying I am neither an engineer nor a time expert. My PhD
> is in statistics and my spouse's PhD is in theoretical computer science,
> working on quantum computer algorithms. Neither of us claims any special
> expertise when it comes to time and frequency measurement. I am a radio
> amateur and I came to this group following a recommendation from John
> Ackermann, who very kindly answered some questions for me regarding the
> amateur radio frequency measurement test. I thoroughly enjoy the dialogue
> here and I think that I have learned a bit about the subject though, by any
> standard of this group, I am the rankest newbie.
> 
> My question is a serious one. I am not trolling, nor am I trying to begin
> an argument, nor am I implying criticism of anyone or any endeavor, here or
> elsewhere.
> 
> What useful purpose, if any, is served by the continuing evolution of
> clocks like NIST-F2 that now achieve accuracy along the lines of one second
> per many billions of years? Are there tangible benefits to be had? I
> consulted an astronomer friend who advised that the current generation of
> clocks would allow a suitable space vehicle to plant a probe squarely in
> the middle of Alpha Centauri, if rocket technology existed to do so. We
> have many friends in the academic computer science community who say that
> neither conventional nor quantum computers that exist at present or in the
> projectable future require anything like this kind of accuracy.
> 
> By no means am I questioning the value of new knowledge qua knowledge. For
> theoreticians like the one to whom I am wedded, no justification is needed
> beyond the words of mountaineer George Mallory: "Because it's there." I'm
> sure that engineers and scientists in the field of time and frequency
> measurement feel the same. From that perspective, there need be no
> rationalization beyond the desire to do it just a little better than it has
> been done.
> 
> Please don't lecture me about the value of science for its own sake. My
> career has largely been built on that principle. I'd like to be informed as
> to present or anticipated applications that require such accuracy. Are we
> developing these incredible devices just to push boundaries? Or do they
> have some practical purpose?
> 
> I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
> be deleted unread.
> 
> Thanks for your help.
> 
> 
> -- 
> Homo sum humani a me nihil alienum puto.
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.


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[time-nuts] The forbidden question

[William H. Fite]

Warning: Potentially heretical material below

Let me begin by saying I am neither an engineer nor a time expert. My PhD
is in statistics and my spouse's PhD is in theoretical computer science,
working on quantum computer algorithms. Neither of us claims any special
expertise when it comes to time and frequency measurement. I am a radio
amateur and I came to this group following a recommendation from John
Ackermann, who very kindly answered some questions for me regarding the
amateur radio frequency measurement test. I thoroughly enjoy the dialogue
here and I think that I have learned a bit about the subject though, by any
standard of this group, I am the rankest newbie.

My question is a serious one. I am not trolling, nor am I trying to begin
an argument, nor am I implying criticism of anyone or any endeavor, here or
elsewhere.

What useful purpose, if any, is served by the continuing evolution of
clocks like NIST-F2 that now achieve accuracy along the lines of one second
per many billions of years? Are there tangible benefits to be had? I
consulted an astronomer friend who advised that the current generation of
clocks would allow a suitable space vehicle to plant a probe squarely in
the middle of Alpha Centauri, if rocket technology existed to do so. We
have many friends in the academic computer science community who say that
neither conventional nor quantum computers that exist at present or in the
projectable future require anything like this kind of accuracy.

By no means am I questioning the value of new knowledge qua knowledge. For
theoreticians like the one to whom I am wedded, no justification is needed
beyond the words of mountaineer George Mallory: "Because it's there." I'm
sure that engineers and scientists in the field of time and frequency
measurement feel the same. From that perspective, there need be no
rationalization beyond the desire to do it just a little better than it has
been done.

Please don't lecture me about the value of science for its own sake. My
career has largely been built on that principle. I'd like to be informed as
to present or anticipated applications that require such accuracy. Are we
developing these incredible devices just to push boundaries? Or do they
have some practical purpose?

I'll appreciate thoughtful answers. Dismissive and/or snarky replies will
be deleted unread.

Thanks for your help.


-- 
Homo sum humani a me nihil alienum puto.
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Re: [time-nuts] Updating the unit of,time: the second.

[Tony Finch]

Attila Kinali  wrote:
> Mike Cook  wrote:
>
> > c. The first commercial cesium clocks were available in 1956, but the
> > second did not get redefined until 1967.  There is no rush.
>
> Which caesium beam standards were available in 1956?

The Atomichron, I think:

http://ieeemilestones.ethw.org/images/8/8d/Forman_Proc_IEEE_1985.pdf

Tony.
-- 
f.anthony.n.finchhttp://dotat.at/
Fair Isle: Southwest 5 or 6, becoming variable 4 later. Moderate or rough.
Showers, rain later. Good, occasionally poor later.

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Re: [time-nuts] Updating the unit of,time: the second.

[Tom Van Baak]

Mike, Attila, Rick,

> Which caesium beam standards were available in 1956?

The Atomichron, made by the National Company. This was the first 
commercial cesium standard; about 50 were made. Attila, you saw one at 
my house when you visited last year. It's about 7 feet tall. The one I 
have was used by NBS(NIST), then made its way to a remote cabin in 
Minnesota for a couple decades, then to a garage in Minneapolis, where I 
bought it and drove it to Seattle. Atomichron photos here [1].


The hp 5060 and 5061 came much later.

> The picture of the beam tube is only a small fraction of the clock 
itself. There are multiple racks full of RF equipment not shown


Correct. Better views of Essen's cesium clock and laboratory here [2]. 
Note also the Atomichron in the background of figure 6.


Since you are interested in the history of atomic clocks, especially 
cesium beam clocks, I highly recommend these papers:


http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S01.pdf
"History of early atomic clocks"
Norman F Ramsey

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S02.pdf
"Essen and the National Physical Laboratory’s atomic clock"
Dale Henderson

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S04.pdf
"Atomic time-keeping from 1955 to the present"
Bernard Guinot, Elisa Felicitas Arias

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_s05.pdf
"The classical caesium beam frequency standard: fifty years later"
Jacques Vanier, Claude Audoin

http://geodesy.unr.edu/hanspeterplag/library/geodesy/time/met5_3_S10.pdf
"Fifty years of commercial caesium clocks"
Leonard S Cutler

The above come from:

https://iopscience.iop.org/issue/0026-1394/42/3
Special issue of Metrologia: “Special issue: fifty years of atomic 
time-keeping: 1955 to 2005”,

Volume 42, Number 3, June 2005.

See also:

https://ieee-uffc.org/about-us/history/uffc-s-history/history-of-atomic-frequency-standards-a-trip-through-20th-century-physics/
"History of Atomic Frequency Standards: A Trip Through 20th Century Physics"
Arthur O. McCoubrey

https://ieee-uffc.org/about-us/history/uffc-s-history/atomichron/
"Atomichron: The Atomic Clock from Concept to Commercial Product"
Paul Forman

https://tycho.usno.navy.mil/ptti/1985papers/Vol%2017_01.pdf
The First Atomic Clock Program: NBS, 1947-1954
Paul Forman

A fine collection of clear photos and historical PDF here:



And finally,

https://nvlpubs.nist.gov/nistpubs/jres/122/jres.122.029.pdf
also found here: https://tf.nist.gov/general/pdf/2907.pdf
or here: https://tf.nist.gov/general/pdf/2917.pdf
"A Historical Review of U.S. Contributions to the Atomic Redefinition of 
the SI Second in 1967"

Michael A. Lombardi

/tvb

[1] http://www.leapsecond.com/museum/nc2001/

[2] 
https://www.researchgate.net/publication/320878080_Two_clocks_that_changed_the_world_The_birth_of_atomic_timekeeping



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