Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Colin2B on 20/11/2016 08:01:56
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Do the results of NIST 2010 relativity test show same result as Pound Rebka
That is, that a lower clock will measure light emitted at a higher level as blue shifted.
I am posting this as a separate thread from "Are NIST 2010 ground relativity test results exactly as relativity predicts?" http://www.thenakedscientists.com/forum/index.php?topic=68961.msg502803#msg502803 out of respect for Timey's request that we not provide explanations in that thread, but just answer the question:
Ethos -
I am not asking questions because I do not know the answers to them.
I do not need to have the difference between a cesium atomic clock and an ion trap clock explained, nor the fact that the ion trap quantum clock must be run in tandem with the more reliable cesium atomic clock, as I explained many posts ago.
I do not need the fact of the potential of the computers reference frame being irrelevant explained to me.
Nor do I need to be told that if one tapped into the fibre optic cable, that there would be different stages of gravity potential in the cable... (That would be true of a vertically aligned cable, but the fact would have no bearing on a tick rate being transmitted through the cable. If it did then the reference frame of the computer would be highly relevant)
People accuse me of not reading their posts... It would seem to me that they have not read mine.
Yes - the NIST results are relativity results...
...The upper clock is blue shifted.
Yes - the Pound Rebka results are Relativity results...
...The gamma ray arriving from the upper frame is blue shifted when it arrives in the lower frame.
NIST = upper frame blue shifted
Pound Rebka = lower frame blue shifted.
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.... - why don't you just answer the question:
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Do the Pound Rebka maths take into account that the emitting source will be blue shifted at top of tower relative to the same emitting source, (or more pertinently, we can describe this as the receiver) at bottom of tower, or not?
However, Nilak has raised a question which is worthy of discussion:
If the comparator is midway between the clocks, what happens to the distance between two pulses as they travel downwards ? I think it should reduce (like redshifting), although the light is blueshifting. What do you think ?
Some background for those not following the previous thread:
By 2010 NIST had developed Al ion clocks which were both small and accurate https://www.nist.gov/news-events/news/2010/02/nists-second-quantum-logic-clock-based-aluminum-ion-now-worlds-most-precise
Far more accurate than the older Cesium fountain clocks:
"In addition to demonstrating that aluminum is now a better timekeeper than mercury, the latest results confirm that optical clocks are widening their lead—in some respects—over the NIST-F1 cesium fountain clock, the U.S. civilian time standard, which currently keeps time to within 1 second in about 100 million years."
Because of the increase accuracy and small size it was now possible to move atomic clocks within the lab, so Nilak, consider the following set up:
Two optical clocks were set up in adjacent laboratories one to remain fixed the other to be raised in height. Fibre optic carries the optical output to a comparator/computer. It would have been possible to shine the light from the raised clock to the comparator so we will also consider if this differs from the fibre optic. The fibre was used because a direct light path would need to be adjusted after the clock was raised but the fibre would not - in fact the fibre can be routed via ceiling, floor, whatever and its final approach to the comparator is irrelevant.
For analysis we will use Nilak's suggestion that the comparator/computer was inbetween the fixed clock and the final raised height of the 2nd clock. As both clock start the experiment at the lower position a direct light path from the either clock would be at a very shallow angle upwards, but all that matters is the vertical distance and hence gravitational potential difference which results in red shift of this light when measured in the frame of the comparator. The same is true of the light travelling through the fibre, no matter what its path it ends up at a higher potential, hence reduced KE, hence red shifted. We could also work this out by considering that time passes faster at this higher potential so in the frame of the comparator the light from the lower clock's frame will appear red shifted.
With the 2nd clock in its lower position, the 2 optical frequencies (clocks) were compared so that the fixed clock now provided a reference. The 2nd clock was then raised in height by 33cm and the optical frequencies again compared.
At this new height the raised clock is above the comparator so both a direct light path and light through a fibre would result in a blue shift when measured at the comparator - either measured as a gain in KE or by considering that clocks run slow at the lower potential hence will measure the arriving light as blue shifted.
However, the comparator is still using the fixed reference frequency against which the raised frequency is compared so giving a result for the frequency difference for a height shift of 33cm. As stated by the experimenters "When this shift is interpreted as a measurement of the change in height of the Al-Mg clock, the result of 37±15 cm agrees well with the known value of 33 cm." - obviously not great accuracy but good proof of concept with the new clocks.
So, we can see that light from a higher clock when measured in the frame of a lower clock (the frequency comparator in this case) will be seen to be blue shifted (higher frequency) and the NIST experiment confirms the findings of Pound Rebka.
Added note: if anyone has not studied relativity you need to know that for the clock which is moved in height, its frequency measured at its own height i.e. in its own frame, is constant and this is what it emits and which then arrives at the comparator and is measured at the frame of the comparator as being red or blue shifted.
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Good - I'm glad you made this thread!
I have read elsewhere on this site that once a signal enters fibre optic cable, the status of the signal itself will be uncorrupted by red shift/blue shift considerations... but will be subject to a slowing caused by transiting the cable.
Therefore it would seem to me that the signal being received from the clock by the computer, is as it was recorded 'at' the clocks reference frame.
A thought experiment:
The frequency of the ground clock is already calibrated at the frequency of a standard second. So if the signal is being read at the computer as a standard second, and the signal of the clock 'is' shifted in the cable, what frequency is the ground clock actually running at?
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Good, you are still thinking.
I have read elsewhere on this site that once a signal enters fibre optic cable, the status of the signal itself will be uncorrupted by red shift/blue shift considerations... but will be subject to a slowing caused by transiting the cable.
Can you find that reference?
Time delays only mean transit times along the cable, doesn't cause a frequency shift, just a delay - like light from the sun but much, much shorter.
It means that if you shone a torch and at same time a light down a cable, at the end of the cable the torch light would win, but only just.
Therefore it would seem to me that the signal being received from the clock by the computer, is as it was recorded 'at' the clocks reference frame..
OK let's think about this. I'll use my eg with simplified numbers because I don't like dealing with too many zeros.
Using 1000Hz let's count 1000 cycles into the cable at the upper level, this takes 1s. This goes down the cable and exits at the computer unchanged. Let's imagine the raised clock is running 2x speed of computer's level, so the computer using local clock counts the 1000 cycles in 0.5s, hence frequency at computer = 2000Hz= blue shift.
Now let's assume that the light in the cable is affected by gravity and progressively blue shifts until it exits the cable at the computer, however, by now it will have been blue shifted into the local time zone and will still read 2000Hz as timed on the computer clock.
A thought experiment:
The frequency of the ground clock is already calibrated at the frequency of a standard second. So if the signal is being read at the computer as a standard second, and the signal of the clock 'is' shifted in the cable, what frequency is the ground clock actually running at?.
Standard second.
They are not measuring actual frequencies in the NIST experiment, just relative frequencies as I described in the first post.
Remember, though that the upper clock is also calibrated at the standard second, and the computer thinks it runs at standard seconds.
EDIT: just a thought, if you wanted to experiment with standard seconds you could assume the fixed clock was standard seconds, the computer running 2x that, and raised clock at 2x the computer level. Work it all through see what you get.
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According to NIST (and who would dare to contradict them?)
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
Note that there is no mention of gravitational potential, which you might think odd as it varies from place to place even on the surface of the earth. The point is that this defines the second wherever you are, and a comparison of clock frequencies will then tell you the gravitational potential difference between two clocks.
In other words, physicists believe that relativity is true and there is no absolute reference frame.
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I understand the status quo Colin. I understand that light is slowed slightly in a cable and that this is just a time delay, not the dilation. I understand that you are saying that the transit to the computer is changing the frequency of the signal, as per the gravity potential of the computers reference frame, but because the reference frame of the computer is being used to compare both the signals, this difference is the same for both the locations the clocks are placed in, and is therefore considered irrelevant.
But...
If NIST is only measuring relative frequencies, then how is the exact frequency of the clock ever known?
Surely the frequency of the clock must have been read in its own reference frame at some point in order to define the length of a standard second?
So if the frequencies of both signals at the computer are relative to the frame of reference of the computer, and are not the frequencies that are actually occurring 'at' the clock, then surely it is a simple matter to make the reference frame of the computer relevant, subtract the changes that the computers reference frame has initiated to the process and arrive at the frequency that both clocks are really running 'at'...
The ground clock should be running at the frequency of the standard second, because the clock is calibrated to do so there, and the upper clock? What frequency will it 'really' be running at?
Yes the clock is calibrated on the ground to run at the rate of a standard second... But they did not recalibrate the clock they jacked up to run at the rate of a standard second. The grohnd clock that is calibrated to run at the rate of a standard second was elevated slightly, and the frequency it ran at was then recorded as increased at the computer which is programmed to think in terms of per standard second.
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If NIST is only measuring relative frequencies, then how is the exact frequency of the clock ever known?
(1) By calibration against a cesium standard at the same gravitational potential and
(2) the absolute value doesn't matter for the relativity experiments. All that matters is the two test clocks run at the same frequency when at the same potential, and their mechanism is not g-dependent.
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As I keep saying...If you view the frequency and energy of the elevated atom as 'actually' increased, then I can see another way of viewing matters that is an altered version of GR that doesn't result in the necessity for the dimensions of dark matter and dark energy to make mathematical sense of the theory...
I think there is scope within the Relativity theory, related experiments, and the maths, for something slightly different to be going on...
But if you are all stuck on viewing matters via the remit of GR 'proper' religiously, then I have no chance of ever explaining my model...
So - should I just stop trying?
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If NIST is only measuring relative frequencies, then how is the exact frequency of the clock ever known?
For this application they didnt need to know it. However, you could have compared against the standard.
Surely the frequency of the clock must have been read in its own reference frame at some point in order to define the length of a standard second?
Not in this experiment, because all the measurements were relative, they were only comparing frequencies.
So if the frequencies of both signals at the computer are relative to the frame of reference of the computer, and are not the frequencies that are actually occurring 'at' the clock, then surely it is a simple matter to make the reference frame of the computer relevant, subtract the changes that the computers reference frame has initiated to the process and arrive at the frequency that both clocks are really running 'at'...
If you want to do that and can find a reference clock etc, yes you can work out the frequencies relative to some arbitary standard like sea level.
The ground clock should be running at the frequency of the standard second, because the clock is calibrated to do so there,
The clock wasn't calibrated because it didn't have the counter/display part just the optical output, but I think this experiment was done a few 100ft above sea level so it would not have been standard second/frequency anyway.
and the upper clock? What frequency will it 'really' be running at?
Accepting that we disagree what 'really' means, you would have to calculate it based on the GP at that upper level relative to your standard.
Yes the clock is calibrated on the ground to run at the rate of a standard second... But they did not recalibrate the clock they jacked up to run at the rate of a standard second.
True, but as these clocks are only the oscillator part you can't so that anyway. If they had the counter display etc, then you could tell it it was running at a higher rate. Question is, how do you do that? A correction is required for every height, of which there are an infinite number. You need to measure the height, measure the GP relative to standard, and apply correction. That's why no one does it, simple experiments become very complex. Best to do it all relative.
The grohnd clock that is calibrated to run at the rate of a standard second was elevated slightly, and the frequency it ran at was then recorded as increased at the computer which is programmed to think in terms of per standard second.
The computer cant be programmed to think in terms of standard second because it doesnt have an accurate enough clock to make these measurements.
That's why it used the feed from the fixed clock as a reference, the computer just compared that to the frequency from above.
As I keep saying...If you view the frequency and energy of the elevated atom as 'actually' increased, then I can see another way of viewing matters that is an altered version of GR that doesn't result in the necessity for the dimensions of dark matter and dark energy to make mathematical sense of the theory...
I think there is scope within the Relativity theory, related experiments, and the maths, for something slightly different to be going on...
But if you are all stuck on viewing matters via the remit of GR 'proper' religiously, then I have no chance of ever explaining my model...
So - should I just stop trying?
As I've said before, it would be useful if you posted a new theory with details of how these frequencies and standard seconds would work out in practice and the effect they have. You could give examples in simplified form rather than get into complex arithmetic. You would need to show how everything fits together, and how you reached your conclusions.
In this section you will only get the current view.
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As I keep saying...If you view the frequency and energy of the elevated atom as 'actually' increased, then I can see another way of viewing matters that is an altered version of GR that doesn't result in the necessity for the dimensions of dark matter and dark energy to make mathematical sense of the theory...
You could say that "deep space", i.e. g = 0, defines the proper frequency of an oscillator. Now assume c is constant, and I fear you will end up with SR and GR just like everyone else, because that is what we observe.
Nobody mentioned dark matter in terms of the NIST clocks: it simply isn't relevant or required to explain the observations. There is, however, a suggestion that something in interstellar space is gluing it all together. Your alternative explanation would be welcome, buit you would do well to begin with the demonstrated fact that the NIST2010 and P&R results are indeed identical..
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You could say that "deep space", i.e. g = 0, defines the proper frequency of an oscillator. Now assume c is constant, and I fear you will end up with SR and GR just like everyone else, because that is what we observe.
I did try working back from 0 g but came to the conclusion that there would be a planet somewhere with the same gravitational potential but moving relative to us, so no standard. I assume that's what you mean by ending up with SR etc, all relative.
I think Timey would need to postulate speed of light is not a constant.
..... Your alternative explanation would be welcome, buit you would do well to begin with the demonstrated fact that the NIST2010 and P&R results are indeed identical..
That reminds me Timey, I assume you are now OK with why clocks are not blue shifted at top of tower etc within relativity, that only occurs in your theory where time, I assume, becomes a constant.
Only guessing, looking forward to you posting detail.
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Timey, I asked the question if gravitons gravitate and then gave an upside down answer. Since it requires a mass of a significant size undergoing acceleration to produce gravitational radiation then these converge in deep space. A significant amount of gravitation may then be self generated in the absence of massive objects. This field effect should have an effect on light passing through it. If it happens at all. It may just cancel out. If not then the voids between and around galaxies should have enough pull to hold together galaxy clusters and consequently affect the path of photons and change their energies. Just a thought. You may disagree.
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Colin - I have posted details of my model on New Theories here on threads that I have created myself, and threads that I have forced myself upon... I just get told that I do not understand relativity, or that the dimensions I propose are meaningless...
...I do understand relativity - and the dimensions of my model are meaningless with respect to what?
The dimensions of my model will be meaningless with respect to the dimensions of GR 'proper'... change the way one looks at just 1 small aspect and the ramifications of the effects this change go on to affect everything.
My model is a theory describing everything, and it is a huge prospect to explain. I've tried doing it all in 1 go, and I've tried doing it in little bit stages regarding certain areas...
I will now try again, in stages, but starting from the beginning and only moving on when each stage has been understood, or understood at least up to the point where I can move on to how the currently discussed stage fits to the next:
http://www.thenakedscientists.com/forum/index.php?topic=69032.new#new
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Here is a diagram featuring two clocks and a mid way receiver. The main reference frame is set so that an object below the lower clock is at rest. Next, it is a constant acceleration diagram and you can see the first order derivative which is speed, is not the same for any two points on the x axis. If you plot an increasing acceleration over time ( like in the case of gravity), you will also always find different velocities. If the acceleration varied randomly , there could've been points with same velocity.
There are four reference frames in the first example, but the idea can be explained using only two reference frames.
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The point about a clock, defining it as a 'constant', is that it locally must give you a same measure
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........or understood at least up to the point where I can move on to how the currently discussed stage fits to the next:
As I've said, I'm happy to discuss your new theory and keep an open mind. However, when you get to the 'currently discussed stage' your theory will have to cope with current experimental results i.e.:
NIST = lower frame blue shifted
Pound Rebka = lower frame blue shifted
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When I get to that stage in the explanation of my model, you will see that a split value of g changes the maths.
You will also see how a standard second can be held as a standard in relativity.
You will understand that where gravity potential does not affect relativistic mass in current maths, that my models maths will result in the fact that gravity potential is an M related phenomenon, and that the value of m does not affect the gravity potential experienced by m near M.
...and that something quite different can be, at least considered and explored, going on within the NIST and Pound Rebka results.
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Here is a diagram featuring two clocks and a mid way receiver. The main reference frame is set so that an object below the lower clock is at rest. Next, it is a constant acceleration diagram and you can see the first order derivative which is speed, is not the same for any two points on the x axis. If you plot an increasing acceleration over time ( like in the case of gravity), you will also always find different velocities. If the acceleration varied randomly , there could've been points with same velocity.
There are four reference frames in the first example, but the idea can be explained using only two reference frames.
The constant acceleration graph is wrong because we need two identical acceleration curves for each clock, only separated on x axis.
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Here is a the diagram showing two clocks.
The clock at the left at moment L has RL point on the same simultaneity line. At SL, left clock stops accelerating and goes at constant speed. This corresponds with SRL from its reference frame. As you can see, at SRL, clock two is moving faster, and it means it has a slower clock rate. In the main reference frame SRL corresponds to SLL. At these moments clocks will show a different time.
However at SL and SR0, clocks read the same time in the main reference frame. So it doesn't seem to be a real time dilation, or is it ?
Approximately the same results we get if instead of an accelerating spaceship we do the experiment on earth in a lab.
Next , I'll try to do the diagrams for three clocks an a receiver.
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Here is the drawing.
The clocks and the receiver are placed in a spaceship that experiences constant proper acceleration, similarly to an object stationary in a constant gravitational field except the co-moving frames will be inertial.
At point A, the receiver gets two flashes of light. At B, it had received 5 flashes from the front clock, and 4 only from the rear clock.
A C it receives a last flash from the front clock but the flashed from the rear never get to it.
In the left clock co-moving reference frame, the pulses are sent at a constant rate, but in the main reference frame the rate appears to slow down because of increasing speed. As the space-time axes tilt towards each other, the clock send pulses at a lower rate. This happens for both clocks but due to asymmetry differences in rates will occur.
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The redshift / blueshift in the chart above is wrong and cannot be explained by SR.
If you replace the light with pulses at constant speed in the main reference frame it works. But if the pulses maintain the same relative speed from the source, blueshift will not happen.