Einstein Special on PBS
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were
in sync then took one to the building at the top of the ski lift
on New Hampshire's Mount Sunapee at 2726' elevation for 4 days
where it would be running a little faster because it would be
slightly further from the center of the spinning earth. After
bringing the 5071A back from the top of the mountain they checked
the difference in the start of square waves displayed on the scope
and detected the 5071A at altitude was now 20ns ahead of the
5071A kept at sea level, as predicted, if I understood everything
correctly. They explained that the clocks in the GPS satellites
traveling at a much higher speed had to correct for the speed
difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
Would've been more fun to see Tom and his kids going to the top of Mt
Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and
general relativity (gravitational) effects. The GR correction is 45
microseconds a day fast; the SR correction is 7 microseconds slow. 38
microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While
time drifts 38 microseconds a day, I'm not sure that GPS coordinates would
drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the
word mass when describing them, just like when I took a course from him in
1990. When my advisor taught the same course, I pleaded with him, "please
use coordinates!". (Kip Thorne loves coordinate-free notation,
unfortunately my brain does not work that way!!! I would've failed the
course if it was only GR; fortunately it also had plasma physics in the
same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were
in sync then took one to the building at the top of the ski lift
on New Hampshire's Mount Sunapee at 2726' elevation for 4 days
where it would be running a little faster because it would be
slightly further from the center of the spinning earth. After
bringing the 5071A back from the top of the mountain they checked
the difference in the start of square waves displayed on the scope
and detected the 5071A at altitude was now 20ns ahead of the
5071A kept at sea level, as predicted, if I understood everything
correctly. They explained that the clocks in the GPS satellites
traveling at a much higher speed had to correct for the speed
difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the transition of a hyperfine line of a certain atom within some element, in this case cesium, In order for any of these clocks to deviate in relative time at different heights for example, it seems to me that the period of the hyperfine transitions must change as well, to make the defined second longer or shorter. So, in these examples the elevation does not change the time, but the way the atoms behave. What obvious item am I missing, besides maybe brain capacity? Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Shoppa
Sent: Friday, November 27, 2015 9:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Would've been more fun to see Tom and his kids going to the top of Mt Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the word mass when describing them, just like when I took a course from him in 1990. When my advisor taught the same course, I pleaded with him, "please use coordinates!". (Kip Thorne loves coordinate-free notation, unfortunately my brain does not work that way!!! I would've failed the course if it was only GR; fortunately it also had plasma physics in the same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were in
sync then took one to the building at the top of the ski lift on New
Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would
be running a little faster because it would be slightly further from
the center of the spinning earth. After bringing the 5071A back from
the top of the mountain they checked the difference in the start of
square waves displayed on the scope and detected the 5071A at altitude
was now 20ns ahead of the 5071A kept at sea level, as predicted, if I
understood everything correctly. They explained that the clocks in the
GPS satellites traveling at a much higher speed had to correct for the
speed difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and
general relativity (gravitational) effects. The GR correction is 45
microseconds a day fast; the SR correction is 7 microseconds slow. 38
microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While
time drifts 38 microseconds a day, I'm not sure that GPS coordinates would
drift that fast - aren't most of the corrections in the same direction?
Hi Tim,
Correct. Here's from the "rel" program (in my http://leapsecond.com/tools/ folder):
C:\tvb\NPR>rel 20000km 14000kph
** Altitude 20000000.000 m (65616797.900 ft, 12427.424 mi) 5.274e-010 blueshift
1898630.424377 ps/hour
45567.130185 ns/day
** Velocity 3888.889 m/s (14000.000 km/h, 8699.197 mph) -8.414e-011 redshift
-302888.070815 ps/hour
-7269.313700 ns/day
** Net effect (GR+SR) 4.433e-010 shift
1595742.353562 ps/hour
38297.816485 ns/day
What this means is that as a source of UTC, GPS would in fact be off by 38 us per day if you forgot about relativity when you designed it.
But, you're right, you cannot blindly turn that "38 us/day" into "11 km/day". As long as all the GPS clocks are running too fast or too slow and as long as the receivers know what that offset is, the navigation system would still work just fine, relativity or not. This is true for any sort of triangulation (actually, trilateration) system.
GPS is a PNT (Position, Navigation, and Timing) system. So while GPS is really cool, and relativity is really cool, the navigation part of GPS does not "depend" on relativity, per-se.
/tvb
Hi Arthur,
That's a good summary. I'm glad you got to visit the mountain. Did you happen to check the elevation? Are there lodges along the road on the way up?
I ask because at 2726 feet a clock will run 9.0e-14 fast (compared with sea level), which is 7.8 ns/day, or 31 ns over 4 days. But they measured 20 ns. So either they didn't stay close to 4 days, or they didn't stay close to the summit or maybe their clock rate was off or they didn't use a high-perf 5071A, or something.
I'll make just a one word correction to your summary. The clocks run a bit faster not because of "the spinning earth" but because of "the earth". In other words, the clocks are experiencing a gravitational effect not a velocity effect. Gravity is a tiny bit less as you rise in elevation and this is what the clocks experience. Presumably the experiment would work fine even if the earth did not spin at all, or spun backwards.
What's confusing is that in articles about relativity and shows like this, they talk about speed and trains and light and stuff (SR, special relativity) and so people are pre-disposed to be thinking in those terms. Worse yet, we know outer points of spinning objects have greater tangential speed than inner points so again people think of speed. There's mention of satellites, also high speed.
But the main thing that is affecting the clocks at home vs. mountain is simply gravity. With a stationary clock at home and a stationary clock on the mountain, there's no velocity to talk about. The situation with airplanes and rockets and satellites is different; in these cases there is a large and combined gravitational and velocity effect.
/tvb
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were
in sync then took one to the building at the top of the ski lift
on New Hampshire's Mount Sunapee at 2726' elevation for 4 days
where it would be running a little faster because it would be
slightly further from the center of the spinning earth. After
bringing the 5071A back from the top of the mountain they checked
the difference in the start of square waves displayed on the scope
and detected the 5071A at altitude was now 20ns ahead of the
5071A kept at sea level, as predicted, if I understood everything
correctly. They explained that the clocks in the GPS satellites
traveling at a much higher speed had to correct for the speed
difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
Hi Mike,
I'm far from an expert on this, but what you're missing is that time and space isn't the same between any two points that are located in different gravity gradients and/or moving at different relative velocities. The hyperfine transitions are happening at the same local rate whether the Cs device is on planet earth, in orbit around the earth, or in close proximity to the sun or even a black hole. But, all of these examples are happening in different space-time environments (i.e. different local frames), so that "relative" to each other, they are experiencing time at different rates.
It might help to think of it in terms of doppler effect, though this is not an exact comparison. But, if you have two clocks that are moving away from each other, they may very well be precisely synchronous, but because of the doppler effect, any measurement you make will show them to be running at different rates. Because of the effects of gravity, watches at different altitudes appear to run at different rates to the outsider, although to the person wearing the watch, nothing has actually changed; it is the other person's watch that is acting funny.
So, essentially, a clock sitting on the ground at sea level is running in a very slightly different space time than one that is sitting on a mountain. And when you place a clock in orbit, you also have 14,000 odd MPH of velocity that's also having an impact on the space-time of that object. As a result, when you bring the prodigal clock back to sea level, it will have experienced a slightly different amount of time than the one at sea level. Note that the prodigal clock hasn't run at a different rate. It has actually experienced time running at a different rate from that of the clock on the ground.
Bob
From: Mike Feher <mfeher@eozinc.com>
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Friday, November 27, 2015 9:37 AM
Subject: Re: [time-nuts] Einstein Special on PBS
I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the transition of a hyperfine line of a certain atom within some element, in this case cesium, In order for any of these clocks to deviate in relative time at different heights for example, it seems to me that the period of the hyperfine transitions must change as well, to make the defined second longer or shorter. So, in these examples the elevation does not change the time, but the way the atoms behave. What obvious item am I missing, besides maybe brain capacity? Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Shoppa
Sent: Friday, November 27, 2015 9:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Would've been more fun to see Tom and his kids going to the top of Mt Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the word mass when describing them, just like when I took a course from him in 1990. When my advisor taught the same course, I pleaded with him, "please use coordinates!". (Kip Thorne loves coordinate-free notation, unfortunately my brain does not work that way!!! I would've failed the course if it was only GR; fortunately it also had plasma physics in the same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were in
sync then took one to the building at the top of the ski lift on New
Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would
be running a little faster because it would be slightly further from
the center of the spinning earth. After bringing the 5071A back from
the top of the mountain they checked the difference in the start of
square waves displayed on the scope and detected the 5071A at altitude
was now 20ns ahead of the 5071A kept at sea level, as predicted, if I
understood everything correctly. They explained that the clocks in the
GPS satellites traveling at a much higher speed had to correct for the
speed difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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Bob -
Thanks for attempting to make me see the light. But, I still do not. You said it yourself that hyperfine transitions remain the same. Since "time" on these device are derived from these transitions, they should also remain the same. I agree, from a relativistic point of vie the time will be different. I am just not convinced that using these types of clocks will demonstrate that. Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Bob Stewart
Sent: Friday, November 27, 2015 12:48 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Hi Mike,
I'm far from an expert on this, but what you're missing is that time and space isn't the same between any two points that are located in different gravity gradients and/or moving at different relative velocities. The hyperfine transitions are happening at the same local rate whether the Cs device is on planet earth, in orbit around the earth, or in close proximity to the sun or even a black hole. But, all of these examples are happening in different space-time environments (i.e. different local frames), so that "relative" to each other, they are experiencing time at different rates.
It might help to think of it in terms of doppler effect, though this is not an exact comparison. But, if you have two clocks that are moving away from each other, they may very well be precisely synchronous, but because of the doppler effect, any measurement you make will show them to be running at different rates. Because of the effects of gravity, watches at different altitudes appear to run at different rates to the outsider, although to the person wearing the watch, nothing has actually changed; it is the other person's watch that is acting funny.
So, essentially, a clock sitting on the ground at sea level is running in a very slightly different space time than one that is sitting on a mountain. And when you place a clock in orbit, you also have 14,000 odd MPH of velocity that's also having an impact on the space-time of that object. As a result, when you bring the prodigal clock back to sea level, it will have experienced a slightly different amount of time than the one at sea level. Note that the prodigal clock hasn't run at a different rate. It has actually experienced time running at a different rate from that of the clock on the ground.
Bob
From: Mike Feher <mfeher@eozinc.com>
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Friday, November 27, 2015 9:37 AM
Subject: Re: [time-nuts] Einstein Special on PBS
I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the transition of a hyperfine line of a certain atom within some element, in this case cesium, In order for any of these clocks to deviate in relative time at different heights for example, it seems to me that the period of the hyperfine transitions must change as well, to make the defined second longer or shorter. So, in these examples the elevation does not change the time, but the way the atoms behave. What obvious item am I missing, besides maybe brain capacity? Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Shoppa
Sent: Friday, November 27, 2015 9:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Would've been more fun to see Tom and his kids going to the top of Mt Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the word mass when describing them, just like when I took a course from him in 1990. When my advisor taught the same course, I pleaded with him, "please use coordinates!". (Kip Thorne loves coordinate-free notation, unfortunately my brain does not work that way!!! I would've failed the course if it was only GR; fortunately it also had plasma physics in the same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were in
sync then took one to the building at the top of the ski lift on New
Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would
be running a little faster because it would be slightly further from
the center of the spinning earth. After bringing the 5071A back from
the top of the mountain they checked the difference in the start of
square waves displayed on the scope and detected the 5071A at altitude
was now 20ns ahead of the 5071A kept at sea level, as predicted, if I
understood everything correctly. They explained that the clocks in the
GPS satellites traveling at a much higher speed had to correct for the
speed difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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Hi Mike,
It's a good question and I've wrestled with it too. I see two choices:
- Time is stable and every ultra-precise timing measurement of atomic behavior appears to depend on gravity.
- Every ultra-precise timing measurement of atomic behavior is stable, and Time appears to depend on gravity.
My impression is they are both equivalent and indistinguishable. Practical people like to use #1, for example, the SI second is defined as 9,192,631,770 Hz specifically and only at mean sea level on planet earth; national laboratories, and some time nuts, correct their clocks for elevation. By contrast, astronomers and physicists use #2 because it make everything simpler and universal.
So you can say that a cesium clock ticks at 9,192,631,770 Hz +/- some function of gravity and velocity, or you can say that a cesium clock always ticks at 9,192,631,770 Hz in its "own reference frame".
But either way, if you leave a clock on a mountain for a while, it comes back the same frequency it left. So what we measure is not the frequency, but the time (clock phase). The time the clock displays contains the sum total history of all frequency changes during the trip. You can't tell this during the trip, since the clock always thinks it is running at a constant and correct rate, wherever it is.
/tvb
----- Original Message -----
From: "Mike Feher" mfeher@eozinc.com
To: "'Discussion of precise time and frequency measurement'" time-nuts@febo.com
Sent: Friday, November 27, 2015 7:37 AM
Subject: Re: [time-nuts] Einstein Special on PBS
I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the transition of a hyperfine line of a certain atom within some element, in this case cesium, In order for any of these clocks to deviate in relative time at different heights for example, it seems to me that the period of the hyperfine transitions must change as well, to make the defined second longer or shorter. So, in these examples the elevation does not change the time, but the way the atoms behave. What obvious item am I missing, besides maybe brain capacity? Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Shoppa
Sent: Friday, November 27, 2015 9:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Would've been more fun to see Tom and his kids going to the top of Mt Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the word mass when describing them, just like when I took a course from him in 1990. When my advisor taught the same course, I pleaded with him, "please use coordinates!". (Kip Thorne loves coordinate-free notation, unfortunately my brain does not work that way!!! I would've failed the course if it was only GR; fortunately it also had plasma physics in the same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were in
sync then took one to the building at the top of the ski lift on New
Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would
be running a little faster because it would be slightly further from
the center of the spinning earth. After bringing the 5071A back from
the top of the mountain they checked the difference in the start of
square waves displayed on the scope and detected the 5071A at altitude
was now 20ns ahead of the 5071A kept at sea level, as predicted, if I
understood everything correctly. They explained that the clocks in the
GPS satellites traveling at a much higher speed had to correct for the
speed difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
Hi Mike,
The time rate does remain the same - at the device. The problem is the idea that it is the hyperfine transitions that determine the time. They are only a measurement of the time in that environment. So, if the rate of time is different at two locations, you will never see it at either location, because the clocks will run at the proper speed in either location; even though the rates are actually different between the two locations. Since you are actually at that location, you can't tell that time runs at a different rate. It is only by comparing the clocks in two different locations that you can determine the difference in space-time between these two locations.
If you are falling into a black hole, your watch will not appear to slow down to you. You will still experience time as if you were sitting on your doorstep at home. (Ignoring the effects of spaghettification, or course.) But generations of people back on earth would live and die for each tick of your watch.
Bob
From: Mike Feher mfeher@eozinc.com
To: 'Bob Stewart' bob@evoria.net; 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Friday, November 27, 2015 12:10 PM
Subject: RE: [time-nuts] Einstein Special on PBS
Bob -
Thanks for attempting to make me see the light. But, I still do not. You said it yourself that hyperfine transitions remain the same. Since "time" on these device are derived from these transitions, they should also remain the same. I agree, from a relativistic point of vie the time will be different. I am just not convinced that using these types of clocks will demonstrate that. Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
Hi Tom -
It has been a while. Well, I guess I am not in bad company if you struggled with this as well. I also like your take on it and will think some more, but it helped. So, if frequency remains the same, then d(phi)/d(t) ratio remains the same and both phase and time must change. Also, the concept that the number of transitions as a function of elevation (gravity) makes very good sense and of course would explain my dilemma. However, I am sure there is still something I am missing. Thanks & Regards - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tom Van Baak
Sent: Friday, November 27, 2015 1:18 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Hi Mike,
It's a good question and I've wrestled with it too. I see two choices:
- Time is stable and every ultra-precise timing measurement of atomic behavior appears to depend on gravity.
- Every ultra-precise timing measurement of atomic behavior is stable, and Time appears to depend on gravity.
My impression is they are both equivalent and indistinguishable. Practical people like to use #1, for example, the SI second is defined as 9,192,631,770 Hz specifically and only at mean sea level on planet earth; national laboratories, and some time nuts, correct their clocks for elevation. By contrast, astronomers and physicists use #2 because it make everything simpler and universal.
So you can say that a cesium clock ticks at 9,192,631,770 Hz +/- some function of gravity and velocity, or you can say that a cesium clock always ticks at 9,192,631,770 Hz in its "own reference frame".
But either way, if you leave a clock on a mountain for a while, it comes back the same frequency it left. So what we measure is not the frequency, but the time (clock phase). The time the clock displays contains the sum total history of all frequency changes during the trip. You can't tell this during the trip, since the clock always thinks it is running at a constant and correct rate, wherever it is.
/tvb
----- Original Message -----
From: "Mike Feher" mfeher@eozinc.com
To: "'Discussion of precise time and frequency measurement'" time-nuts@febo.com
Sent: Friday, November 27, 2015 7:37 AM
Subject: Re: [time-nuts] Einstein Special on PBS
I just do not get it. I know that now I am 70 and my good smart days are behind me, but, this should be simple. In all these clocks mentioned, time is derived from the transition of a hyperfine line of a certain atom within some element, in this case cesium, In order for any of these clocks to deviate in relative time at different heights for example, it seems to me that the period of the hyperfine transitions must change as well, to make the defined second longer or shorter. So, in these examples the elevation does not change the time, but the way the atoms behave. What obvious item am I missing, besides maybe brain capacity? Thanks - Mike
Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Shoppa
Sent: Friday, November 27, 2015 9:19 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Einstein Special on PBS
Would've been more fun to see Tom and his kids going to the top of Mt Ranier in 2005 with the ensemble :-). http://leapsecond.com/great2005/
They mentioned some "6 miles per day" offset due to GPS relativity effects.
I think this is the sum of both special relativity (time dilation) and general relativity (gravitational) effects. The GR correction is 45 microseconds a day fast; the SR correction is 7 microseconds slow. 38 microseconds seconds is 11 kilometers which is indeed 6 or 7 miles. While time drifts 38 microseconds a day, I'm not sure that GPS coordinates would drift that fast - aren't most of the corrections in the same direction?
Seeing Kip Thorne describe black holes was a blast - he refused to use the word mass when describing them, just like when I took a course from him in 1990. When my advisor taught the same course, I pleaded with him, "please use coordinates!". (Kip Thorne loves coordinate-free notation, unfortunately my brain does not work that way!!! I would've failed the course if it was only GR; fortunately it also had plasma physics in the same quarter, and I was an ace at that due to some undergraduate work.)
Tim N3QE
On Fri, Nov 27, 2015 at 12:05 AM, Arthur Dent golgarfrincham@gmail.com
wrote:
In the special it looks like they used two HP5071A standards, an
SRS620 counter, and a scope. They first made sure the stds were in
sync then took one to the building at the top of the ski lift on New
Hampshire's Mount Sunapee at 2726' elevation for 4 days where it would
be running a little faster because it would be slightly further from
the center of the spinning earth. After bringing the 5071A back from
the top of the mountain they checked the difference in the start of
square waves displayed on the scope and detected the 5071A at altitude
was now 20ns ahead of the 5071A kept at sea level, as predicted, if I
understood everything correctly. They explained that the clocks in the
GPS satellites traveling at a much higher speed had to correct for the
speed difference which also verified Einstein's theory.
My wife and I were on the top of Mt. Sunapee this summer where we
enjoyed the views but didn't run any experiments. ;-)
-Arthur
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