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 <[email protected]>
To: 'Discussion of precise time and frequency measurement'
<[email protected]>
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:[email protected]] 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 <[email protected]>
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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