[timey (OP)]

Are the NIST 2010 ground level relativity test results exactly as relativity predicts?

The clocks in this experiment are measured by counters that are 'in' the reference frame with the clock they are measuring.  The counters counting the frequency of these time dilated clocks are giving the results of relativity maths.

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame, and will not be time dilated 'in' their own reference frame?

(Please note: All mention of rockets, space ships, or anything that does not directly pertain to the NIST 2010 relativity experiments are hereby banished from this thread.)

[jeffreyH]

Yes.

[timey (OP)]

Yes to which question Jeff?

Yes relativity predicts that a clock will be time dilated 'in' its own frame of reference?

Or...

Yes relativity predicts that a clock will only appear time dilated as viewed 'from' another frame of reference?

[Ethos_]

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame, and will not be time dilated 'in' their own reference frame?

The term: "Acceleration of Gravity" has an effect on the "observed" passage of time. One clock positioned at a different elevation from another will in effect, be in a different frame of reference from the other. When you suggest that these clocks are in the same reference frame, you are mistaken timey.

Why you continue to resist acknowledging this simple fact has become quite frustrating. Until you recognize this simple relationship, your error will not be reconciled.

[Janus]

Are the NIST 2010 ground level relativity test results exactly as relativity predicts?

The clocks in this experiment are measured by counters that are 'in' the reference frame with the clock they are measuring.  The counters counting the frequency of these time dilated clocks are giving the results of relativity maths.

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame, and will not be time dilated 'in' their own reference frame?

(Please note: All mention of rockets, space ships, or anything that does not directly pertain to the NIST 2010 relativity experiments are hereby banished from this thread.)

In Relaitivity, when we are dealing with inertial frames of reference you will only observe time dilation if you are at rest with respect to a different frame of reference than the clock you are observing,  When you are in a non-inertial frame, this is not the case, and you can measure time dilation in clocks that share your frame depending on their position in the frame.   This includes linearly accelerating frames, rotating frames, and frames in a gravity field (where this test was made).

[evan_au]

For those who aren't familiar with the specifics of this experiment, here is the link:
https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale

They used ion-trap clocks containing aluminum/aluminium ions.

By the way, timey, if NIST found a deviation from the predictions of general relativity with their new, super-accurate clocks, you can be sure they would have made a lot more noise about it (after a lot of checking - you would be brave to bet against Einstein!).

[jeffreyH]

Yes to which question Jeff?

Yes relativity predicts that a clock will be time dilated 'in' its own frame of reference?

Or...

Yes relativity predicts that a clock will only appear time dilated as viewed 'from' another frame of reference?

Neither. It was in response to the question in the title of the thread. You can choose not to believe the answer if you wish.

[timey (OP)]

Are the NIST 2010 ground level relativity test results exactly as relativity predicts?

The clocks in this experiment are measured by counters that are 'in' the reference frame with the clock they are measuring.  The counters counting the frequency of these time dilated clocks are giving the results of relativity maths.

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame, and will not be time dilated 'in' their own reference frame?

(Please note: All mention of rockets, space ships, or anything that does not directly pertain to the NIST 2010 relativity experiments are hereby banished from this thread.)

In Relaitivity, when we are dealing with inertial frames of reference you will only observe time dilation if you are at rest with respect to a different frame of reference than the clock you are observing,  When you are in a non-inertial frame, this is not the case, and you can measure time dilation in clocks that share your frame depending on their position in the frame.   This includes linearly accelerating frames, rotating frames, and frames in a gravity field (where this test was made).

Janus - Let us just consider the NIST moving clock experiment for now...

There is a counter 'in' the stationary clock's frame 'with' the clock counting its frequency.
We understand that the stationary clock at ground level runs at a particular frequency and the counter with that clock is confirming that this is so...

The moving clock was reported to have shown signs of time dilation at speeds as low as 36km/h.
So how was the moving clock measured?

Was there a counter 'in' the moving frame of reference, 'with' the moving clock, counting the frequency of its cycles?

[Bored chemist]

Q
" Are NIST 2010 ground relativity test results exactly as relativity predicts?"

A
"In one set of experiments, scientists raised one of the clocks by jacking up the laser table to a height one-third of a meter (about a foot) above the second clock. Sure enough, the higher clock ran at a slightly faster rate than the lower clock, exactly as predicted."

From
https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale
cited earlier by Evan

[timey (OP)]

Q
" Are NIST 2010 ground relativity test results exactly as relativity predicts?"

A
"In one set of experiments, scientists raised one of the clocks by jacking up the laser table to a height one-third of a meter (about a foot) above the second clock. Sure enough, the higher clock ran at a slightly faster rate than the lower clock, exactly as predicted."

From
https://www.nist.gov/news-events/news/2010/09/nist-pair-aluminum-atomic-clocks-reveal-einsteins-relativity-personal-scale
cited earlier by Evan

For crying out loud, Boring Chemist.  Do we have to keep on reiterating the blatantly obvious?

I am opening this discussion on the basis that everyone has understood the blatantly obvious, that we can progress to discussing the detail... and...

The detail I am discussing is about WHERE these observations are being observed 'from'.

P.S.  I've posted that link on this forum must be a dozen times over the last 2 years, thanks.

[alancalverd]

You could just read the experimental writeup, but if you insist on reading it here, all clocks at the same gravitational potential keep the same time if they are not moving with respect to one another. Clocks at different gravitational potentials run at different speeds, and clocks at the same gravitational potential lose synchronisation if they move relative to one another..

Obviously the only way you will know if there is a difference is if you compare one with another. It doesn't matter where or how you do the comparison because A - B = (A+X) - (B+X) regardless of the value of X. In the special case of X = 0 we are obviously observing  one clock from the reference frame of the other, but even if the observer was doing aerobatics on Alpha Centauri, and A and B were in Boulder, Co., he would still see the same difference between A and B.

[timey (OP)]

I read about the experiment in the National newspapers in 2010 when it was breaking news, have read the write ups, and been thinking rather deeply about it ever since, thanks.

If the moving clock is being measured by a counter that is 'in' the clock's own reference frame, this is contradictory to the relativity remit of this clock only appearing to be time dilated from another frame of reference.

Damn it Alan - you are the one who keeps telling me that an atom doesn't know if it is moving or not...right?
And that a clock only 'appears' time dilated from another reference frame...right?

[jeffreyH]

I read about the experiment in the National newspapers in 2010 when it was breaking news, have read the write ups, and been thinking rather deeply about it ever since, thanks.

If the moving clock is being measured by a counter that is 'in' the clock's own reference frame, this is contradictory to the relativity remit of this clock only appearing to be time dilated from another frame of reference.

Damn it Alan - you are the one who keeps telling me that an atom doesn't know if it is moving or not...right?
And that a clock only 'appears' time dilated from another reference frame...right?

You really don't get it.

[timey (OP)]

Jeff - What is the point of your post above?  It is saying nothing at all!

Anytime I have tried talking on this forum about an atom having a different frequency when moving relative to a stationary clock, (or when in a different gravity potential), I am being 'told' that the atom does not experience a difference in frequency, that an atom does not 'know' if it is moving or not, that the atom is actually operating at a frequency that is the same as the stationary clock, and that the 'appearance' of a difference in frequency (this being the frequency that the NIST experiment results in) is only observable 'from' another reference frame, and is 'not' observable of the moving clock to an observer 'with' the moving clock...

So again I ask - In the NIST experiment, was the counter counting the frequency of the moving clock 'in' the reference frame 'with' the moving clock?

[nilak]

This reminds me of Einstein. Everyone thought the experiments results were erroneous and the theory was right. It turned out to be the opposite. But you can never be 100% sure. For example a possible problem is one way speed of light which is debatable.

[alancalverd]

So again I ask - In the NIST experiment, was the counter counting the frequency of the moving clock 'in' the reference frame 'with' the moving clock?

And again I say it doesn't matter where the observer is in relation to either clock. All the counter was doing was measuring the difference between them, which was determined entirely and only by their relative speed and relative gravitational potential.

Many people find the twin paradox confusing because it is based on an impossible thought experiment in which two clocks magically appear in an otherwise empty universe, with a relative velocity. In any real experiment we start with two clocks in a laboratory or at least stationary and equipotential with respect to each other, and then accelerate one of them. As Einstein pointed out (but few people seem to have read his footnote!) this makes the clocks different and distinguishable as far as the experiment is concerned, so reciprocity is compromised.

[Ethos_]

Jeff - What is the point of your post above?  It is saying nothing at all!

On the contrary timey, he along with the rest of us is saying that, for what ever reason, you simply don't grasp what is blatantly obvious to those that understand relativity.

You are in error to assume that the clocks are in the same reference frame just because they may only be centimeters apart. Because the gravitational potential is different for each clock, they are not in the same frame of reference. And to repeat what many of us have pointed out: There exists no preferred frame of reference.

The only frame where both clocks are in the same frame would be one where they both reside at the same elevation and are at rest relative to each other.

It's very "elementary dear Watson".

[timey (OP)]

So again I ask - In the NIST experiment, was the counter counting the frequency of the moving clock 'in' the reference frame 'with' the moving clock?

And again I say it doesn't matter where the observer is in relation to either clock. All the counter was doing was measuring the difference between them, which was determined entirely and only by their relative speed and relative gravitational potential.

Many people find the twin paradox confusing because it is based on an impossible thought experiment in which two clocks magically appear in an otherwise empty universe, with a relative velocity. In any real experiment we start with two clocks in a laboratory or at least stationary and equipotential with respect to each other, and then accelerate one of them. As Einstein pointed out (but few people seem to have read his footnote!) this makes the clocks different and distinguishable as far as the experiment is concerned, so reciprocity is compromised.

Does this mean that I can now enter into a discussion with you about an FE57 physically having an increased frequency when located in a higher gravity potential, relative to an FE57 located in a lower gravity potential - Alan?

Edit : Ethos - Nowhere have I said the clocks are in the same reference frame, so your post is, at best, misconceived.

[Ethos_]

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame,

Yes

and will not be time dilated 'in' their own reference frame?

Yes, every frame sees it's own time not dilated. And in the NIST experiment, we're looking at 3 frames of reference and not just 2. #1 clock, #2 clock, and the scientific observers.

[timey (OP)]

But doesn't relativity predict that these clocks will only be observed to be time dilated 'from' another reference frame,

Yes

and will not be time dilated 'in' their own reference frame?

Yes, every frame sees it's own time not dilated. And in the NIST experiment, we're looking at 3 frames of reference and not just 2. #1 clock, #2 clock, and the scientific observers.

Sorry Ethos, but we just got through to the fact that NIST experimenters are recording the frequency of the clocks in the clocks own reference frames.

Can you spot the difference?

Because this means that although the observer in the frame with the clock will experience his clock as normal, his clock 'is' time dilated...
(...and this fact has a bearing on my longstanding discussion with Alan concerning Pound Rebka.)