Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: katieHaylor on 06/07/2017 12:59:20
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Ken says:
After reading about Planck and the Ultraviolet Catastrophe I wondered if it implied that there is a maximum electromagnetic (EM) frequency and conversely a minimum EM frequency? I think this is the same as asking if there is a minimum and maximum wavelength for Electro-Magnetic Radiation?
What do you think?
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: Best answer at Stack Exchange
There is no maximum or minimum wavelength, any wavelength can be transformed into another one with the right choice of reference frame. A possible exception to this is if quantum gravity breaks Lorentz symmetry, and then there will be some minimum Planck-scale wavelength.
This answer was so concise I just had to copy and paste it across...
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Ok so let's think about the maximum wavelength. That implies an infinite length. That equates to a frequency of zero or maybe undefined. Let's think about a minimum wavelength. It can't be zero because of zero point energy. This all implies some limit on the range.
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Some extreme limits (rather loose):
- A photon can't have a wavelength greater than the size of the universe
- A single photon can't have an energy greater than the energy of the universe
It is thought that in the high energy environment of the early universe, all 4 fundamental forces would have been unified, so it is questionable whether a photon as such would be "a photon" as we know it.
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What about looking at the fact that any wavelength can be transformed into another one with the right choice of reference frame?
Which choice of reference frame would result in equating a wavelength the size of the universe?
Which choice of reference frame would result in equating a photon with the same amount of energy as the universe?
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God's frame of reference?
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Huh?
Can I just check with you - in the statement "any wavelength can be transformed into another one with the right choice of reference frame", what do you think is meant by "the right choice of reference frame'?
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Huh?
Can I just check with you - in the statement "any wavelength can be transformed into another one with the right choice of reference frame", what do you think is meant by "the right choice of reference frame'?
My interpretation was this: Imagine a beam of monochromatic light (EM radiation) of Frequency F0 when observed by a someone at rest with respect to the source. If our observer approaches the source at velocity (0 < v < c), the observed frequency will be higher with greater velocity, and arbitrarily high as v approaches c. Similarly, if the observe moves away from the source, the observed frequency will decrease to arbitrarily low values as v approaches c.
This is only one way to change the reference frame. One can also imagine different gravitational potentials etc.
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Ah yes... very good. But lets simplify the matter and use GR time dilated clocks situated at rest with respect to the gravity field in different gravity potentials. We measure a clock that is in the higher gravity potential it has one wavelength. To change the wavelength of the clock we have just measured we can move the clock we are measuring to a different gravity potential, or leave the clock that we are measuring in the same location and simply move our own position in the gravity potential.
Just saw your edit, posting anyway.
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So you can see that things can be quite interesting (in a loose kind of way) where I have asked this question:
Which choice of reference frame would result in equating a wavelength the size of the universe?
Which choice of reference frame would result in equating a photon with the same amount of energy as the universe?
If we transpose the question as regarding the wavelength of a clock:
Then a wavelength the size of the universe would be 1 tick of the clock.
And the minutely short wavelength that would be associated with the incredibly high frequency that would result from all the energy in the universe, would result in clock ticks that are so close together there would be no telling them apart.
One might draw this scenario as a graph like this:
* *
_____________
Where the 2 dots represent 1 tick of the long wavelength clock, and the line represents, crikes don't ask me how many, ticks of the short wavelength clock.
Where am I going with this? Well fact is that you could only measure each of these reference frames as being those wavelength from the other.
If I make the graph look like this:
* *
~~~~~~~~~~~
____________
Where the wavy line in-between is a longer wavelength that is causing the clock there to tick slower than the short wavelength clock, and we are now measuring from the clock ticking at this wavelength, then this will alter our measurements of the first two clocks.
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The above suggests (in a loose kind of way) that it clearly is quite pertinent to the measurement as to the choice of tick rate one is using to measure with... For instance the age of the universe in relation to it's size.
But it is also quite interesting to think (in these loose terms) about the physics of these reference frames from which it would be possible to measure these hypothetical extremes.
In relation to the wavelength of a clock, the wavelength the size of the universe would occur in the lowest possible gravity potential, and the shortest wavelength would occur in the highest possible gravity potential...
However, let's now transpose the consideration back to the remit of EM radiation, and what we now find is that the longest wavelength will occur in the highest possible gravity potential, and the shortest wavelength in the lowest possible gravity potential.
Can anyone tell me about the factors that must therefore differ within the gravitational shift equation for a clock, and the gravitational shift equation for EM radiation?
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Some extreme limits (rather loose):
- A photon can't have a wavelength greater than the size of the universe
Not true. You can in principle generate a radio wave of any frequency greater than zero, so however large the dimenson d of the universe may be, you can envisage a photon of such minute energy E = hf that c/f > d.
But
- A single photon can't have an energy greater than the energy of the universe
is obviously true.
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I'm not quite sure it can be so clear cut as all that Alan. It depends on whether the distance in which the universe exists is finite or infinite doesn't it? If it is finite then the hypothetical longest wavelength can only be as long as the distance within which the universe exists.
And, as the quote in post 1 states:
Best answer at Stack Exchange
There is no maximum or minimum wavelength, any wavelength can be transformed into another one with the right choice of reference frame. A possible exception to this is if quantum gravity breaks Lorentz symmetry, and then there will be some minimum Planck-scale wavelength.
...Doesn't the choice of reference frame affect the measurement of any length wavelength?
Also, isn't there a minimum energy?
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:Jerzy Michał Pawlak, PhD in High Energy Physics (experimental)
there is actually a lower limit for the photon energy, and it comes from the uncertainty principle. In another formulation it states, that the product of energy and time uncertainty is of the order of Planck constant. To produce a low energy photon you therefore need more time, than to produce a higher energy one. Another way to see it is thinking about frequency - you can't really say you produced a wave, unless you wait for a time in the order of the period of this wave. So, the minimal photon energy is of the order of E=ℏ/T, where T is the age of the universe.
Which was what I was saying (in not such a concise form) in post 9...
So - going back to post 10:
In relation to the wavelength of a clock, (edit: electron transitions) the wavelength the size of the universe would occur in the lowest possible gravity potential, and the shortest wavelength would occur in the highest possible gravity potential...
However, let's now transpose the consideration back to the remit of EM radiation, (edit: photons) and what we now find is that the longest wavelength will occur in the highest possible gravity potential, and the shortest wavelength in the lowest possible gravity potential.
Can anyone tell me about the factors that must therefore differ within the gravitational shift equation for a clock, and the gravitational shift equation for EM radiation?
For instance - Are the gravitational shifts of electron transitions of the same magnitude as the gravitational shifts of photons when subject to the same differences in gravity potential?
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In relation to the wavelength of a clock, (edit: electron transitions) the wavelength the size of the universe would occur in the lowest possible gravity potential, and the shortest wavelength would occur in the highest possible gravity potential...
However, let's now transpose the consideration back to the remit of EM radiation, (edit: photons) and what we now find is that the longest wavelength will occur in the highest possible gravity potential, and the shortest wavelength in the lowest possible gravity potential.
Can anyone tell me about the factors that must therefore differ within the gravitational shift equation for a clock, and the gravitational shift equation for EM radiation?
For instance - Are the gravitational shifts of electron transitions of the same magnitude as the gravitational shifts of photons when subject to the same differences in gravity potential?
Bump...
Surely someone here at this forum can answer the question?
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There is no requirement for electromagnetic waves to be "complete" within a universe.
Fix one end of a string to a rock, then lift the free end and lower it. The string describes half a wavelength. The length of an open organ pipe is half the wavelength of its fundamental frequency. So whether the universe is closed or open, you can generate an electromagnetic wave of any frequency and thus any wavelength within it, even if you can't measure the wavelength because it is bigger than the observable universe.
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Yes - I can appreciate the truth in what you are saying Alan.
Is there any chance that you could answer the question I posed?
I am (have been for a long time) interested in understanding if a clock that shifts to a higher frequency in a higher gravity potential compared to a lower gravity potential (within the mathematical framework of GR) is shifting to the same magnitude as a photon shifts to a lower frequency when moving from the same lower potential to the same higher potential (within the mathematical framework of GR)...
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There is no requirement for electromagnetic waves to be "complete" within a universe.
On reflection, Jeff's mention of zero point energy returns to the consideration. Isn't this a limiting factor?
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My interpretation was this: Imagine a beam of monochromatic light (EM radiation) of Frequency F0 when observed by a someone at rest with respect to the source. If our observer approaches the source at velocity (0 < v < c), the observed frequency will be higher with greater velocity, and arbitrarily high as v approaches c. Similarly, if the observe moves away from the source, the observed frequency will decrease to arbitrarily low values as v approaches c.
This is only one way to change the reference frame. One can also imagine different gravitational potentials etc.
So beautifully put it almost brought a tear to me eye! :) I simply could not have said it better myself. In fact when I saw this thread I was going to say almost the exact same thing, just phrased differently. But you phrased it better than I would have.
BTW - How to I do a "Thank you" for a post? I can't see a link to do it with.
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Ok so let's think about the maximum wavelength. That implies an infinite length. That equates to a frequency of zero or maybe undefined. Let's think about a minimum wavelength. It can't be zero because of zero point energy. This all implies some limit on the range.
Well spot the stupid mistake. Zero point energy relates to an infinite wavelength. A wavelength approaching zero is also approaching infinite energy. And no one spotted THAT?
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Is there any chance that you could answer the question I posed?
I am (have been for a long time) interested in understanding if a clock that shifts to a higher frequency in a higher gravity potential compared to a lower gravity potential (within the mathematical framework of GR) is shifting to the same magnitude as a photon shifts to a lower frequency when moving from the same lower potential to the same higher potential (within the mathematical framework of GR)...
We've been round this loop several times before. Yes, the gravitational effect on clock synchronisation is exactly the same as on photon frequency, as predicted and measured.
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:wiki
Zero-point energy (ZPE) or ground state energy is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly fluctuate in their lowest energy state due to the Heisenberg uncertainty principle.[1] As well as atoms and molecules, the empty space of the vacuum has these properties. According to modern physics the universe can be thought of not as isolated particles but continuous fluctuating fields: matter fields, whose quanta are fermions (i.e. leptons and quarks), and force fields, whose quanta are bosons (e.g. photons and gluons). All these fields have zero-point energy.[2] These fluctuating zero-point fields lead to a kind of reintroduction of an aether in physics,[1][3] since some systems can detect the existence of this energy. However this aether cannot be thought of as a physical medium if it is to be Lorentz invariant such that there is no contradiction with Einstein's theory of special relativity.[1]
Physics currently lacks a full theoretical model for understanding zero-point energy, in particular the discrepancy between theorized and observed vacuum energy is a source of major contention.[4] Physicists Richard Feynman and John Wheeler calculated the zero-point radiation of the vacuum to be an order of magnitude greater than nuclear energy, with one teacup containing enough energy to boil all the world's oceans.[5] Yet according to Einstein's theory of general relativity any such energy would gravitate and the experimental evidence from both the expansion of the universe, dark energy and the Casimir effect show any such energy to be exceptionally weak. A popular proposal that attempts to address this issue is to say that the fermion field has a negative zero-point energy while the boson field has positive zero-point energy and thus these energies somehow cancel each other out.[6][7] This idea would be true if superstring theory were an exact symmetry of nature. However, the LHC at CERN has so far found no evidence to support supersymmetry. Moreover, it is known that if supersymmetry is valid at all, it is at most a broken symmetry, only true at very high energies, and no one has been able to show a theory where zero-point cancellations occur in the low energy universe we observe today.[7] This discrepancy is known as the cosmological constant problem and it is one of the greatest unsolved mysteries in physics. Many physicists believe that "the vacuum holds the key to a full understanding of nature"
Jeff - please take note:
'These fluctuating zero-point fields lead to a kind of reintroduction of an aether in physics,[1][3] since some systems can detect the existence of this energy. However this aether cannot be thought of as a physical medium if it is to be Lorentz invariant such that there is no contradiction with Einstein's theory of special relativity.'
ChiralSPO - if you are wondering where the little wet patch on your butt cheek came from, it's from when Pete kissed it, post 18. He does have a point though, and I was wondering if you might speak a little on "the axis of evil' preffered direction observations in relation to the inflation model here:
https://www.thenakedscientists.com/forum/index.php?topic=70532.msg516048#msg516048
Ah Alan - good, you answered. I have further questions for you and will be back.
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If we have a problem with vacuum energy then we are not thinking of this energy in the correct way.
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Is there any chance that you could answer the question I posed?
I am (have been for a long time) interested in understanding if a clock that shifts to a higher frequency in a higher gravity potential compared to a lower gravity potential (within the mathematical framework of GR) is shifting to the same magnitude as a photon shifts to a lower frequency when moving from the same lower potential to the same higher potential (within the mathematical framework of GR)...
We've been round this loop several times before. Yes, the gravitational effect on clock synchronisation is exactly the same as on photon frequency, as predicted and measured.
So - I take it from your answer that you are telling me that when subject to the same differences in gravity potential, that the gravitational shift of electron transitions and the gravitational shift of photons are equal in magnitude.
On the basis that we just look at this as a logical venture rather than a text book quotation, now I would like you to consider 'where' these observations are taking place:
The gravitational shift in electron tansitions will be obseved to be of a higher frequency in the higher potential than the electron transitions observed in the lower potential, 'from' the lower potential.
The gravitational shift in photons will be observed to be of a lower frequency than they were observed to be in the lower potential, 'in' the higher potential.
Photons cannot be observed unless they are 'in' the observers reference frame.
Electron transitions can be observed 'in' another reference frame 'from' the observers reference frame.
A clock shifts to a higher frequency 'in' the higher potential. If we go to this higher potential the clock apears to be ticking normally, but this is because 'in' the higher potential we won't be measuring the electron transitions of this clock from the clock with the lower frequency 'in' the lower potential.
The light in the lower potential is measured via the clock with a lower frequency of electron transitions.
The light in the higher potential is measure via the clock with a higher frequency of electron transitions.
...Yet the light measured in the higher potential via the clock with the higher frequency of electron transitions has a lower frequency than the light measured in the lower potential via the clock with the lower frequency of electron transitions.
In the framework of GR, the clock's electron transitions are shifting to higher frequencies in the higher potential. (time gets faster at elevation)
In the framework of GR, the photon is shifting to a lower frequency in the higher potential 'according' to the clock in the higher potential.
If the magnitude of the shifts of both electron transitions and photons is equal, then has the light actually shifted frequency?
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Zero point energy
Ok so let's think about the maximum wavelength. That implies an infinite length. That equates to a frequency of zero or maybe undefined. Let's think about a minimum wavelength. It can't be zero because of zero point energy. This all implies some limit on the range.
Well spot the stupid mistake. Zero point energy relates to an infinite wavelength. A wavelength approaching zero is also approaching infinite energy. And no one spotted THAT?
Zero point energy does not mean that a particle has zero energy. It means that its lowest energy a system can have. See:
https://en.wikipedia.org/wiki/Zero-point_energy#Redefining_the_zero_of_energy
Zero-point energy (ZPE) or ground state energy is the lowest possible energy that a quantum mechanical system may have.
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BTW - How to I do a "Thank you" for a post? I can't see a link to do it with.
Look at the Top RHS of the Post - there is a dark blue button labelled "ACTIONS".
Click this button; the top menu item under this is "Say Thanks".
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To continue from post 23:
The clue: (time gets faster at elevation).
If the clock's electron transitions are increased in frequency because time is running faster at elevation, then the light measured at elevation will also have increased in frequency as the clock's electron transitions have, but this increase in frequency has been gravitationally shifted to a lower frequency.
Logically speaking, the gravitational shift of the light and the gravitational shift of the electon transitions of the clock are not going to 'actually' be equal and opposite, the light has shifted twice as much as the clock has.
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Oh dear. Here we go again.
The clock at altitude appears faster to an observer on the ground. Fact.
The photon emitted at altitude appears blueshifted to an observer on the ground. Fact.
Same phenomenon, same equation.
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Alan - sigh, you are not reading the posts properly, and I am trying to understand 'how' the equation is 'physically' working.
I am referring to a gravitationally red shifted photon viewed 'in' the higher potential and it's frequency compared to the frequency it was when it was at ground level. I am not referring to a gravitationally blue shifted photon viewed 'in' the lower potential.
The clock at altitude not only appears to be ticking faster from the ground, it IS ticking faster according to the mathematical framework of GR.
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Timey. It all depends upon where the observer is with respect to the origin of the observed event. That is all there is to it. You can't mix up reference frames and get a sensible answer.
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Zero point energy
Ok so let's think about the maximum wavelength. That implies an infinite length. That equates to a frequency of zero or maybe undefined. Let's think about a minimum wavelength. It can't be zero because of zero point energy. This all implies some limit on the range.
Well spot the stupid mistake. Zero point energy relates to an infinite wavelength. A wavelength approaching zero is also approaching infinite energy. And no one spotted THAT?
Zero point energy does not mean that a particle has zero energy. It means that its lowest energy a system can have. See:
https://en.wikipedia.org/wiki/Zero-point_energy#Redefining_the_zero_of_energy
Zero-point energy (ZPE) or ground state energy is the lowest possible energy that a quantum mechanical system may have.
It was all very badly worded.
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Hey Jeff - thanks for the answer. Btw, bad wording or not, I understood exactly what you were referring to in your posts. In my posts I did in fact state quite clearly which reference frames I was referring to. Please remember that light cannot be measured 'in' any other frame apart from the observers frame, and the clock can only be measured as time dilated 'from' another reference frame.
In fact what I am going to do is re-post my question:
:timey post 23
So - I take it from your answer that you are telling me that when subject to the same differences in gravity potential, that the gravitational shift of electron transitions and the gravitational shift of photons are equal in magnitude.
On the basis that we just look at this as a logical venture rather than a text book quotation, now I would like you to consider 'where' these observations are taking place:
The gravitational shift in electron tansitions will be obseved to be of a higher frequency in the higher potential than the electron transitions observed in the lower potential, 'from' the lower potential.
The gravitational shift in photons will be observed to be of a lower frequency than they were observed to be in the lower potential, 'in' the higher potential.
Photons cannot be observed unless they are 'in' the observers reference frame.
Electron transitions can be observed 'in' another reference frame 'from' the observers reference frame.
A clock shifts to a higher frequency 'in' the higher potential. If we go to this higher potential the clock apears to be ticking normally, but this is because 'in' the higher potential we won't be measuring the electron transitions of this clock from the clock with the lower frequency 'in' the lower potential.
The light in the lower potential is measured via the clock with a lower frequency of electron transitions.
The light in the higher potential is measure via the clock with a higher frequency of electron transitions.
...Yet the light measured in the higher potential via the clock with the higher frequency of electron transitions has a lower frequency than the light measured in the lower potential via the clock with the lower frequency of electron transitions.
In the framework of GR, the clock's electron transitions are shifting to higher frequencies in the higher potential. (time gets faster at elevation)
In the framework of GR, the photon is shifting to a lower frequency in the higher potential 'according' to the clock in the higher potential.
If the magnitude of the shifts of both electron transitions and photons is equal, then has the light actually shifted frequency?
:timey post 26
To continue from post 23:
The clue: (time gets faster at elevation).
If the clock's electron transitions are increased in frequency because time is running faster at elevation, then the light measured at elevation will also have increased in frequency as the clock's electron transitions have, but this increase in frequency has been gravitationally shifted to a lower frequency.
Logically speaking, the gravitational shift of the light and the gravitational shift of the electon transitions of the clock are not going to 'actually' be equal and opposite, the light has shifted twice as much as the clock has.
Alan has said:
:Alan
Oh dear. Here we go again.
The clock at altitude appears faster to an observer on the ground. Fact.
The photon emitted at altitude appears blueshifted to an observer on the ground. Fact.
Same phenomenon, same equation.
...But I am talking about light that is emitted 'in' the lower potential that has been redshifted on it's way 'to' the higher potential, and is being measured 'in' the higher potential in comparison to the shift of the clock 'in' the higher potential compared to the lower potential that is observed 'from' the lower potential. All reference frames are clearly stated.
Edit: And where Alan has said:
:Alan
The clock at altitude appears faster to an observer on the ground. Fact.
It is important to remember that the clock not only appears to be faster to an observer on the ground, it IS physically ticking faster according to the mathematical structure of GR.
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Maybe I should pose the question around your answer Alan...same question, just reversed.
:Alan
The clock at altitude appears faster to an observer on the ground. Fact.
The photon emitted at altitude appears blueshifted to an observer on the ground. Fact.
Same phenomenon, same equation.
OK - so now we are comparing the clock 'in' the higher potential with the clock in the lower potential which is observed 'from' the higher potential to have a lower frequency. (time running slower).
And we are comparing the frequency of light emitted 'in' the higher potential, with it's blue shifted frequency as measured 'in' the lower potential via the tick rate of the lower potential clock.
You have said that subject to the same differences in gravity potential, the shift of the light and the shift of the clock are equal in magnitude.
The blue shifted light measured 'in' the lower potential via the lower potential clock (slower rate of time) is of a higher frequency than it was when measured 'in' the higher potential via the higher potential clock (faster rate of time).
The light moving into the lower potential will be affected by this slower rate of time which will affect it's frequency, yet it's frequency is observed 'in' the lower potential to be greater then it was 'in' the higher gravity potential where the rate of time is faster.
Logically speaking, the shift of the light between these higher and lower potentials will be twice the magnitude of the shift of the clock between these higher and lower potentials.
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Just stick to simple and factual.
Everything works normally when viewed from the same gravitational potential. But if the observer is at a lower potential than the source, the source appears blue shifted, whether the source is an atomic clock (low energy photon) or a mossbauer (high energy) photon. These are experimental facts. A simple mathematical model is that spacetime is warped by gravity.
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My déjà vu is having déjà vu.
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Not again, surely?
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My déjà vu is having déjà vu.
Yeah - Mine too!
Just stick to simple and factual.
Everything works normally when viewed from the same gravitational potential. But if the observer is at a lower potential than the source, the source appears blue shifted, whether the source is an atomic clock (low energy photon) or a mossbauer (high energy) photon. These are experimental facts. A simple mathematical model is that spacetime is warped by gravity.
Erm, I'm not sure what your point is... You seem to be stating the basic facts laid out in every physics book I've read, again, as you have done so many times before, to what end I do not know, it's not like I'm unfamiliar. You certainly are not following the remit of examining 'the choice of reference frames' as part of a discussion that pertains to the correct answer to the thread title question which I posted in post 1.
What I want to take part in here at this forum Alan is a dissection of these simple facts by examining physical process, which is what my questions are regarding. But since you have responded with the so called simple and factual let's dissect that first:
Everything works normally when viewed from the same gravitational potential
I think this could be better defined as: Everything is measured as normal when measured by the tick rate of a clock in the same gravity potential.
But if the observer is at a lower potential than the source, the source appears blue shifted, whether the source is an atomic clock (low energy photon)
Electron transitions are not low energy photons. General Relativity states within its mathematical framework that the clock is not just appearing to be ticking faster in the higher potential, it IS ticking faster in the higher potential. That IS factual.
or a mossbauer (high energy) photon
When the observer is at a lower potential to the 'source', the photon the observer is observing is not 'in' the higher potential. It is 'in' the lower potential when it is observed by the observer. A photon cannot be observed anywhere except 'in' the reference frame of the observer. That IS factual
These are experimental facts. A simple mathematical model is that spacetime is warped by gravity.
Where the simple fact is that this mathematical model clearly states that it does not know 'how' spacetime is warped by gravity.
Therefore, in that it is know fact of physics that the best mathematical model of gravity cannot physically describe itself, and a well known fact at that, I would like to discuss know physics experiments in a dissection of examining 'how' the known equations are working in physical terms. This is not unlike the type of considerations that I read about in books written by physicists. These books have taught me physics and I am merely following suit on the style of investigation of known physics that I read about in books, and programs, made by prominent physicists in the field.
So - now we have cleared up the simple and the factual, can we please move onto the consideration that I outlined?
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Just stick to simple and factual.
Everything works normally when viewed from the same gravitational potential. But if the observer is at a lower potential than the source, the source appears blue shifted, whether the source is an atomic clock (low energy photon) or a mossbauer (high energy) photon. These are experimental facts. A simple mathematical model is that spacetime is warped by gravity.
The presence of such a blue shift does not prove that spacetime is curved spacetime. In fact Einstein's predictions of this phenomena is based on physics on the flat spacetime approximation, i.e. by assuming the field is a uniform gravitational field. In fact he utilized the equivalence principle which states that a uniform gravitational field is equivalent to a uniformly accelerating frame of reference (in flat spacetime). Then he used the physics of accelerated frames to make the prediction. In the Pound-Rebka experiments it was this uniform g-field (flat spacetime) approximation that the results of the experiment were compared to. In fact a perfectly uniform gravitational field has zero spacetime curvature.
If you'd like you can look it up in the article Does a gravitational red shift necessarily imply that spacetime is curved? by G.E. Marsh and C. Nissim-Sabat. Am. J. Phys. Vol. 43, No. 3, March (1975)
This article is available online at: http://booksc.org/book/34148429/e7d2fe
Abstract
Schild’ has proposed a heuristic agrument which attempts, to show that any gravitational red shift requires that the geometry of space−time be curved. It is our intention to show that this argument is fallacious and we believe that no argument which attempts to infer space−time curvature solely from the gravitational red shift can be valid.
Does a gravitational red shift necessarily imply that spacetime is curved? by G.E. Marsh and C. Nissim-Sabat. Am. J. Phys. Vol. 43, No. 3, March (1975)
Or I can derive it myself here if anybody would like? Of you can read about it in a paper I wrote which is online here
https://arxiv.org/abs/physics/0204044
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Ah Pete - I'm not sure if you are actually observing my posts or not (you keep saying that you have placed me on ignore) - but I cannot thank you enough for posting this excellent link!
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
Alan - note that Marsh and Nissim-Sabat directly echo the considerations I outlined.
@Mike Gale
You might want to check this link out Mike
edit: - and Pete's paper too.
https://arxiv.org/ftp/physics/papers/0204/0204044.pdf
Great paper Pete. I identified with Einstein's "Relativity, The Special and General Theory" much more than the other modern books I've read dedicated to the subject. It's such a shame (as far as I'm concerned) that you refuse to speak to me because I do not converse in the language of mathematics.
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Ah Pete - I'm not sure if you are actually observing my posts or not (you keep saying that you have placed me on ignore) - but I cannot thank you enough for posting this excellent link!
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
You're welcome. After all, that's what the website is for. But it's odd. I was told that website was going to be deleted. Hmmmmmm.....
And yes, you're in my ignore list. However, since I'm now a moderator I'm responsible for making sure that members don't violate forum rules. It's difficult to juggle this combination, i.e. when to read and when not to so I have to do my best.
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Happy to have alerted you to the continued presence of the website. I simply copied and pasted your description and it was the first item.
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Happy to have alerted you to the continued presence of the website. I simply copied and pasted your description and it was the first item.
Thanks.
I deleted the rest of your post because being a moderator means enforcing the forum rules and your response violated those rules. You cannot simply place judgment calls on someone like that, i.e. assume they meant something when there's nothing in their response to indicate it. I certainly never mean what you always assume I mean. And when you make such claims its quite rude and therefore violates forum rules.
That doesn't mean that you can't tell someone what you think. That's what a PM is for. You do not chew someone out in the forum like you have a tendency to do. Especially being as wrong as often as you are. And I know because I am the worlds leading authority on what I think and why I say what I do and I can tell you as a fact that in all cases you have been wrong.
I'm stating this in open forum so that everyone one here knows that it's wrong to make assumptions about peoples motives. If you think they meant something then simply ask them. Do not accuse them. Do so in PM if you must. I will delete all such accusations when I see them. Accuse people on your own time and in private. It has nothing to do with the subject at hand
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I deleted your post again for the same reason - airing your personal gripes in open forum. Don't do it again.
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In response to timey
GR, like SR, is a mathematical model based on the idea that observation equals reality.
You would do well to review your understanding of atomic clocks, but the mechanism of the clock is irrelevant if you use the GR approach.
At present we do not have much of an idea as to how gravity works, because we have not identified a long-range mass-dependent attractant carrier.
I gather there is some background spat between timey and PmbPhy and I've been asked to intervene, but in the absence of the evidence all I can say is that I am delighted to have made two such robustly and eloquently outspoken friends through this forum, and I hope you will both adopt a similar attitude. But then I was brought up on a diet of Kipling:
Oh, East is East, and West is West, and never the twain shall meet,
Till Earth and Sky stand presently at God's great Judgment Seat;
But there is neither East nor West, Border, nor Breed, nor Birth,
When two strong men stand face to face though they come from the ends of the earth!
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:)
Did you read the link Alan?
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
Whether posted by purposeful design, or coincidence, this link echoes that which I was outlining to you in post 31 and 32.
You would do well to review your understanding of atomic clocks, but the mechanism of the clock is irrelevant if you use the GR approach.
Could you please outline what your contention is with my understanding of atomic clocks?
I understand, to describe in the most basic terms, that a microwave beam resonating at a certain frequency causes electron transitions in atoms. When viewed in a potential differing from that of the observer, this resonating frequency causing electron transitions is observed to differ. The amount by which the frequency differs is predicted by GR, therefore the clock not only appears to be ticking faster in the higher potential 'from' a lower potential, it IS actually ticking faster.
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Good reference. Note in particular
What’s wrong with Schild’s argument? First one needs to be careful when interpreting the statement "The frequency of light decreases..." Caution must be exercised when using "the" when discussing relativity. The frequency reckoned but which observer?
which is why I always stick to the pedantic statement "....when observed by an observer at the lower gravitational potential..."
Electron transitions, and more importantly in the case of atomic clocks, hyperfine spin-spin transitions, are associated with the absorption or emission of photons, from x-rays through the visible spectrum and down to microwaves. However you observe the characteristic photon of an atomic clock, it appears to have a higher energy if the clock is at a higher gravitational potential than the observer. Why "appears to"? (a) because that's a statement of experimental observation and (b) the electron spin vector is only quantised by interacting with the magnetic moment of the nucleus , which isn't changed by gravitation. If it was, then the bandwidth as well as the observed centre frequency would change with gravitational potential.
For the benefit of anyone who hasn't seen this before: three blokes on a train in Patagonia saw a black cow and a white cow in a field. The statistician said "half the cows in Patagonia are black". The mathematician said "There is at least one black cow in Patagonia" and the physicist said "I see two bovine quadrupeds, at least one side of one of which is black".
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I dont quite think so. Maybe our technology cannot support to make the frequency as low or as high as what we want it to be.
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........the electron spin vector is only quantised by interacting with the magnetic moment of the nucleus , which isn't changed by gravitation. If it was, then the bandwidth as well as the observed centre frequency would change with gravitational potential.
The point Alan makes here is an important one.
Consider also the transitions themselves. If we have 2 observers in different gravitational potentials and midway between the 2 we set off a flash of light to indicate start of counting the transitions, and a second flash to indicate stop counting, both observers will count the same number of transitions. However, start and stop are simultaneous events for both observers so the nature of the transitions has not changed, only the time over which each observer measures the transitions and hence calculates the frequency. So it is the difference in time which is the issue, not a fundamental change in the transitions. As Alan points out, using the to describe a frequency needs to be done with caution and it is far better to describe what is measured by each observer.
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What I think it is important to realise is that any photon that is emitted by the clock in the higher potential has been blueshifted by the time it is observed in the lower potential. If you minus the magnitude of the blueshift then the clock isn't ticking faster. General relativity states that the clock is indeed ticking faster. This is where G.E. Marsh and C. Nissim-Sabat make their argument in response to Schild.
Electron transitions, and more importantly in the case of atomic clocks, hyperfine spin-spin transitions, are associated with the absorption or emission of photons, from x-rays through the visible spectrum and down to microwaves. However you observe the characteristic photon of an atomic clock, it appears to have a higher energy if the clock is at a higher gravitational potential than the observer. Why "appears to"? (a) because that's a statement of experimental observation and (b) the electron spin vector is only quantised by interacting with the magnetic moment of the nucleus , which isn't changed by gravitation. If it was, then the bandwidth as well as the observed centre frequency would change with gravitational potential.
Please note (and believe me I am literally crawling at snails pace through the maths in the link), that it is indeed a gravity potential consideration that is being added.
On the basis that General Relativity and Quantum are incompatible, this is of interest to me. Any comment?
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Maybe it'll eventually click, maybe it won't...
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Maybe it'll eventually click, maybe it won't...
If you are indeed responding to my post, and not someone else's...
Maybe what will eventually click Jeff?
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Which choice of reference frame would result in equating a wavelength the size of the universe?
EM waves have the problem that the universe has at certain times been opaque to them, which effectively prevents them from being the width of the universe.
But if we move away from just EM waves, some researchers are searching for gravitational waves that were once almost the size of the universe. It is thought that quantum fluctuations in the early universe (microseconds after the Big Bang) would have produced gravitational waves. Because the universe would have become transparent to gravitational waves in this early epoch of the universe, they might be detectable now (with the right detectors).
Some teams are trying to build detectors that would pick up relic gravitational waves that have frequencies as high as 1011 Hz (compared to the 50-1000Hz detectable by LIGO).
But the theory of cosmic inflation suggests that the very early universe expanded faster than the speed of light for a short time, and so since that time, no waves could be formed that are the width of the universe.
See: https://en.wikipedia.org/wiki/Inflation_(cosmology)
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Maybe it'll eventually click, maybe it won't...
If you are indeed responding to my post, and not someone else's...
Maybe what will eventually click Jeff?
I was replying to Colin.
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Which choice of reference frame would result in equating a wavelength the size of the universe?
EM waves have the problem that the universe has at certain times been opaque to them, which effectively prevents them from being the width of the universe.
But if we move away from just EM waves, some researchers are searching for gravitational waves that were once almost the size of the universe. It is thought that quantum fluctuations in the early universe (microseconds after the Big Bang) would have produced gravitational waves. Because the universe would have become transparent to gravitational waves in this early epoch of the universe, they might be detectable now (with the right detectors).
Some teams are trying to build detectors that would pick up relic gravitational waves that have frequencies as high as 1011 Hz (compared to the 50-1000Hz detectable by LIGO).
But the theory of cosmic inflation suggests that the very early universe expanded faster than the speed of light for a short time, and so since that time, no waves could be formed that are the width of the universe.
See: https://en.wikipedia.org/wiki/Inflation_(cosmology)
http://news.stanford.edu/news/2014/march/physics-cosmic-inflation-031714.html
https://www.newscientist.com/article/dn25293-space-time-ripples-hint-at-physics-beyond-the-big-bang/
https://www.newscientist.com/article/mg23230970-700-cosmic-coincidences-everything-points-in-one-direction/
Here are some more detailed links about the cosmic microwave background and gravitational waves.
This is what Lee Smolin said in his book "The Trouble With Physics" written in 2006:
:Lee Smolin
An oscillation at a wavelength of the scale R takes up a huge part of the sky - about 60 degrees; consequently we see only a few wavelengths, and there are only a few pieces of data, so what we are seeing may just be a random statistical fluctuation. The chances of the evidence for a preferred direction being a statistical anomaly have been estimated at less than 1 part in 1000. But is may be easier to believe in this unlikely bad luck than to believe that the predictions of inflation are breaking down.
But the point that I am trying to make here is that the 'length' of a wave-period is reliant upon which rate of time one measures the wavelength from. The choice of reference frame one measures from affects the measurement.
For instance - if we (hypothetically) measure a wavelength from a reference frame where a clock is ticking really fast, the wavelength will 'appear' longer than if you measure it from a reference frame where a clock is ticking really slow.
Then it becomes very pertinent indeed to consider the fact that the measurement of 'lights' wavelength can only be measured as it is 'in' the reference frame that the observer is observing from, and that any wavelength observed is shifted by the gravitational field it travels through before it reaches the observers frame. Where it is important to note the fact that a clock's wavelength is observed 'from' the lower potential to decrease when the clock is placed in a higher gravity potential, as compared to the clock that is observed in the lower potential, that GR predicts that this time dilation is a physical reality, and most importantly that light shifting from the lower potential into the higher potential will be observed 'in' the higher potential, measured via the faster ticking higher potential clock, to be of a longer wavelength compared to when it was measured in the lower potential via the slower ticking clock.
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Doppler shift: the origin or base frequency (determined by design and settings of emitter) remains constant, but perceived frequency varies with motion of emitter or detector or both.
Measure the freq approaching as f1. Measure the freq receding as f2.
Base freq f=sqrt(f1*f2).
In a g-field, observing a static clock A results in a perceived doppler shift depending on
observer position relative to A. Moving A to a different position changes it's base frequency.
A clock is a frequency so why should there be any difference from photon to clock?
Light loses energy in leaving the surface of a mass. A clock runs slower on the surface than above it, so what's the difference?
And then there's the light clock! (it’s a clock and it’s light)
What do you think?
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Doppler shift: the origin or base frequency (determined by design and settings of emitter) remains constant, but perceived frequency varies with motion of emitter or detector or both.
I'd like to make one point clear here in case someone takes your comment as meaning that there's some sort of optical illusion going on here.
I'm going to point out that there's nothing "perceived" about the frequency of light. The frequency of light is completely undetermined by its origin and only determined by the frame of reference in which its measured. Its almost impossible (or perhaps it really is as yet impossible) to speak of the emitter of the photons which constitute the 3K microwave background radiation.
A clock is a frequency so why should there be any difference from photon to clock?
Because a clock is not a frequency. It merely ticks at a certain frequency. The rate at which a clock ticks is merely one property of a clock. Also there are frames of reference in which a clock is at rest but there are no frames of reference in which a photon can be at rest. A clock has rest mass, a photon doesn't. A clock has a temperature, a photon doesn't. etc.
Light loses energy in leaving the surface of a mass.
That's a common misconception. As reckoned by any observer at rest relative to the source of the gravitational field, the energy of a photon is constant as if moves through field as its is frequency. Only the locally measured energy and frequency are different.
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Doppler shift: the origin or base frequency (determined by design and settings of emitter) remains constant, but perceived frequency varies with motion of emitter or detector or both.
Measure the freq approaching as f1. Measure the freq receding as f2.
Base freq f=sqrt(f1*f2).
In a g-field, observing a static clock A results in a perceived doppler shift depending on
observer position relative to A. Moving A to a different position changes it's base frequency.
A clock is a frequency so why should there be any difference from photon to clock?
Light loses energy in leaving the surface of a mass. A clock runs slower on the surface than above it, so what's the difference?
And then there's the light clock! (it’s a clock and it’s light)
What do you think?
Alrighty phyti... :) I am really appreciating your post.
A clock is a frequency so why should there be any difference from photon to clock?
Light loses energy in leaving the surface of a mass. A clock runs slower on the surface than above it, so what's the difference?
According to Marsh and Nissim-Sabat (as far as I can make out from the maths) the clock (in the higher potential) is considered to have additional gravity potential energy (still waiting for an authority on maths to confirm this for me)
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
And this brings us back to Alan's consideration
:Alan, post 45
Electron transitions, and more importantly in the case of atomic clocks, hyperfine spin-spin transitions, are associated with the absorption or emission of photons, from x-rays through the visible spectrum and down to microwaves. However you observe the characteristic photon of an atomic clock, it appears to have a higher energy if the clock is at a higher gravitational potential than the observer. Why "appears to"? (a) because that's a statement of experimental observation and (b) the electron spin vector is only quantised by interacting with the magnetic moment of the nucleus , which isn't changed by gravitation. If it was, then the bandwidth as well as the observed centre frequency would change with gravitational potential.
On the basis that General Relativity and Quantum are not compatible theories, can anyone else see why this may be interesting?
What do you think?
I think the same thing that every physicist I've read concludes, this being that there is something about the nature of 'time' that physics is missing.
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Which choice of reference frame would result in equating a wavelength the size of the universe?
The assumption here is that in selecting a frame of reference relative to the photon, it does not affect the size of the universe.
No-one is quite sure how you would unambiguously determine the boundaries of the universe (or even if it has any boundaries), but...
- if you select a hypothetical photon that is emitted at the source with a wavelength of 4.1 billion light-years (30% of the width of the observable universe = 13.8 billion light-years)
- then accelerate away from the source such that the wavelength of the photon is now 13.8 billion light-years (nominally the width of the observable universe)
- then you would find that in your new frame of reference, the width of the universe is no longer 13.8 billion light years, but something different
- and,what's more, the width is different looking forwards/backwards or sideways/up/down!
The other way of fiddling with time is to use gravitational wells:
- If you put the source of photons with 4.1 billion light-year wavelength in a deep gravitational well, the photons will lose energy climbing out of the well, and it is true that they may well end up with a wavelength of 13.8 billion light-years.
Speculation: If the universe has no specific boundary, it is possible that photons of this wavelength will interfere destructively with themselves if the size of the universe is not an integral number of wavelengths. So perhaps wavelengths might be quantised on very large scales (but they would take longer than the current age of the universe to interfere with themselves, and by then the size of the universe would have changed....)
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Which choice of reference frame would result in equating a wavelength the size of the universe?
The assumption here is that in selecting a frame of reference relative to the photon, it does not affect the size of the universe.
Ok - well working from an assumption that there is only one universe, as opposed to a multiverse, if the universe started off as a point then the space that the universe is expanding into is being created as per the expansion. Therefore the size of the universe is related to it's age. But as we are calculating the age of the visible universe by the remit of observation of wavelengths, wavelengths that we are measuring via the tick rate of a clock, then both the waves that we are observing to make this assessment and the clock we are measuring the period of the waves via are subject to different measurements dependent on which choice of reference frame.
From our reference frame, here on earth, the age of the universe will 'perhaps' differ from a measurement taken elsewhere in the universe.
This is why (I think at least) that it is important to consider the fact that light and a clock are shifting frequency in opposing directions in the gravity field, i.e. the clock according to GR is increasing in frequency in the higher gravity potential, and the light according to GR is decreasing in frequency in the higher gravity potential. And that for the light to be measured 'in' the higher potential via the 'faster' ticking clock as decreased in frequency compared to how it was previously measured 'in' the lower potential measured via the 'slower' ticking clock is highly pertinent. Highly pertinent because the clock is telling us that time is running faster 'at' altitude, therefore the light must also be affected by this faster rate of time where it's frequency 'should' increase as the clock's has, but the light is measured by the faster ticking clock as being a lower frequency. By remit of logic the light is decreased in frequency by twice the magnitude that the clock is increased in frequency.
This train of thought was outlined by Marsh and Nissim-Sabat in the link that Pete posted.
The fact that it is the gravity field that is causing these frequency changes is then pertinent to the measurement of the exact age of the universe.
However, I have noticed that gravity field assessment becomes fuzzy in the face of the necessity for Dark Matter to describe the observed motion of galaxies...
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Timey;
the clock according to GR is increasing in frequency in the higher gravity potential, and the light according to GR is decreasing in frequency in the higher gravity potential.
If the clock is a light clock, this looks like a contradiction.
GR requires so much math just to get nano sec results! That must be why it has little interest for me. It won't change Dominoes's slogan to "we deliver within 30 ns of expected delivery time".
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If you are with the clock on its journey out of a gravity well the frequency never changes.
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But Jeff, according to GR the frequency of your clock 'is' changing.
Let's place 10 cesium atomic clocks, 20 metres apart in elevation. Before you start your journey to 200 metres elevation, (where you will stop at each 20 metres elevation and compare your personal cesium atomic clock to the clock that is situated there), you will, from this lower potential, observe that each clock at each elevation is ticking faster than the clock below. When you arrive at each elevation with your personal clock, your clock will be ticking at the same rate as the clock that is at that elevation. This being because your personal clock has also increased it's tick rate. Any measuring device that you take into the higher potential will be thus affected. From the lower potential you are measuring a faster tick rate in the higher potential because your clock is ticking slower. When you take your clock into the higher potential, it will be ticking faster.
You will think that your personal clock is ticking at the same rate at each elevation because the frequency that your clock is ticking at will be the same at each elevation, this being 9,192,631,770 Hz. But the reason why it will always be 9,192,631,770 Hz is because you are measuring via the tick rate of the clock at that elevation that is ticking faster, as is your personal clock.
Go to the clock at the elevation below, and measure the clock above with your personal clock, and it will be ticking faster than 9,192,631,770 Hz. Measure the clock at the elevation below with your personal clock, and it will be ticking slower than 9,192,631,770 Hz. *Repeat this procedure at each elevation and the higher clock will always be ticking the same amount faster than 9,192,631,770 Hz, and the lower clock will always be ticking the same amount slower than 9,192,631,770 Hz.
(*I think this is the case, if not then I'd appreciate someone telling me because it would be of interest to me if I am wrong)
Furthermore, this being the most interesting point, you will at each elevation measure the speed of light as being 299 792 458 m/s, but the length of a second is NOT the same at each elevation!
So how does the Shapiro effect testing of GR manage to be consistent with SR?
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Ok. So is your reference frame inertial or non inertial? Or is it the magic pixie frame of reference. "where is my mind, where is my mind ... "
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Yes indeed - where is your mind?
http://www.newenglandphysics.org/physics_world/gr/c_in_gfield.htm
:link
This is exactly the result obtained by Einstein in 1907 [2]. The speed of light in Eq. (5) is known as the coordinate speed of light. Eq. (4) states that as light rises in a uniform gravitational the coordinate speed will increase. If the light travels in the opposite direction the coordinate speed of light will decrease.
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... Way out in the water, see it swimmin' ...
Oh yes the coordinate speed of light. What IS the one way speed?
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Ok so your clock is ticking faster so it now detects the frequency of light as lower. The light could be thought of as being exactly the same frequency and it is your comparison rate that has changed. However this is not the correct way to view things.
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... Way out in the water, see it swimmin' ...
Oh yes the coordinate speed of light. What IS the one way speed?
https://www.technologyreview.com/s/421603/the-one-way-speed-of-light-conundrum/
https://en.wikipedia.org/wiki/One-way_speed_of_light
:wiki
The "one-way" speed of light from a source to a detector, cannot be measured independently of a convention as to how to synchronize the clocks at the source and the detector.
...where light that is shifting frequency in the different gravity potentials, and clocks that are shifting frequency in the different gravity potentials will complicate matters even more.
But you know this already Jeff, don't you?
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Ok so your clock is ticking faster so it now detects the frequency of light as lower. The light could be thought of as being exactly the same frequency and it is your comparison rate that has changed. However this is not the correct way to view things.
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
This is the link that Pete posted. Didn't you read it?
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I've read it before. I have also read relativity texts and understood the mathematics. So I'm not exactly a newbie. There are reasons why precision of language matters. If the brain surgeon said to the nurse pass me the doo dah whatsit, it wouldn't exactly inspire confidence. Just because incorrect terminology in physics doesn't result in physical harm shouldn't be an excuse for abusing it.
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I did not abuse any physics terminology. I simply described a scenario with 11 clocks. It is you who started asking what the frames should be called, in a most derogatory fashion I might add. Magic pixie frame indeed!!! Since you are the moderator, and you are so well read, why don't you simply name all 11 of them, and while you're at it, you might consider NOT asking questions that do not have an answer. What IS the one way speed of light, indeed!!!
If you do not wish to talk about the fact that GR states that clocks at elevation DO tick faster, then don't. Simple as that really Jeff, but don't be thinking that you will be making posts that are clearly trying to give the impression that my understanding is at fault. I didn't think it relevant to the conversation to name any reference frame as inertial or non-inertial. If you did then the ball was in 'your' court to define these frames and state 'why' it was relevant, not mine.
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This being because your personal clock has also increased it's tick rate.
No, it's because you are now at the same gravitational potential as the clock you are looking at. If you bring your mossbauer receiver with you, you will find that photons emitted at your present level are not blue shifted, though they appeared to be when you were at a lower level. But the mossbauer detector has no "moving parts" - it simply absorbs photons of a specific energy.
It's all to do with relativity - the relative gravitational potential, or acceleration, or velocity, of the source and observer.
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If you bring your mossbauer receiver with you, you will find that photons emitted at your present level are not blue shifted, though they appeared to be when you were at a lower level.
Firstly - when you observed the photons emitted 'at' the higher level 'from' the lower level, those photons emitted at the higher level cannot be observed until they reach the lower level. In travelling 'from' the higher level 'to' the lower level, those photons will be blueshifted by the change in potential between the higher level and the lower level.
Secondly - when you are 'in' the higher level measuring the frequency of the light being emitted 'in' the higher level, you will be measuring via the tick rate of the clock 'in' the higher level. If your light source emitter is emitting photons at the same frequency 'in' the higher level as it did when it was 'in' the lower level, then measuring via the clock 'in' the higher level will result in those photons emitted 'in' the higher level being measured as a lower frequency.
This does not occur. Which strongly suggests that the photon source itself is emitting higher energy photons 'in' the higher level and that the mossbauer detector 'in' the higher level is absorbing at a higher energy level.
Because the photon emitter and the mossbauer detector 'in' the higher level will be subject to a higher gravity potential energy, and the link below where Marsh and Nissim-Sabat are specifically adding a gravity potential consideration to the maths - where we are all more than aware of the fact that General Relativity and Quantum are not compatible theories, surely you can see why this is interesting?
http://www.geocities.ws/physics_world/gr/grav_red_shift.htm
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You cannot escape locality. That is the only place a measurement can be made. You are comparing two separate frames. One local and the other remote. Yet other forces could be affecting the remote frame. You would never know. Since you aren't there to make measurements. You only ever get data at the point of measurement. Everything else is speculation. You can however have multiple observers comparing results.
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This is why mathematical frameworks such as GR and Quantum are of import. Both are speculations that have been tested by experiment to be relevant. Any further speculation as to how GR and Quantum may be unified would also have to be tested by experiment. Note that speculation comes before experiment. On the basis that GR has passed every test so far, we can use the premise of GR with some degree of confidence in order to further speculate. It is by using the premise of GR that I have further speculated.
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Huh?
Can I just check with you - in the statement "any wavelength can be transformed into another one with the right choice of reference frame", what do you think is meant by "the right choice of reference frame'?
My interpretation was this: Imagine a beam of monochromatic light (EM radiation) of Frequency F0 when observed by a someone at rest with respect to the source. If our observer approaches the source at velocity (0 < v < c), the observed frequency will be higher with greater velocity, and arbitrarily high as v approaches c. Similarly, if the observe moves away from the source, the observed frequency will decrease to arbitrarily low values as v approaches c.
This is only one way to change the reference frame. One can also imagine different gravitational potentials etc.
The problem with this is connected to energy conservation. Say we started with energy coming from a specific hydrogen electron transition. This defines our energy balance, which we have added to the universe. Although we can see red and blue shifted energy this does not mean we can subtract or add energy to the universe and still maintain the energy balance. Relative reference can create an energy illusion.
For example, from a distance we may see what appears to be more an energetic photon due to the blue shift. However, when the photon hits the original hydrogen again, the original transition happens. This make it appear like we now have a speical form of hydrogen that does not exist.
My biggest problem with relativity is although we will see tangible affects in space and time (d,t) many of these violate energy conservation (m). Relativity explains what we see and measure, but not necessarily energy conservation.
For example, the sun rotates allowing us to see a red shift on the side that moves away and blue shift on the side that moves toward us. However, the sun is emitting relatively uniformly in terms of atomic absorption and emissions. From great distances this may not appear to be the case even though it is.
In terms of general relativity the driving force is mass. Mass is an invariant and therefore controls space-time, in an absolute so it too is invariant. This allows an energy balance. Relative reference, which only looks at space and time and not mass, directly, can out variant; relative, since you lead with a variant. The question i have is can we directly measure relativistic mass so we can absolutely map the universe; energy balance?
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Puppypower - What you are saying comes under the remit of the cosmological constant problem.
https://en.wikipedia.org/wiki/Cosmological_constant_problem
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Another phrasing: Perceived time is constant, as if there is a universal time.
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After all the exchanges, the clock rate is up or down, the potential is high or low, etc...
for me, the time invested isn't worth the returns.
I am still sympathetic to Timey's quest for a believable theory for gravitational fields.
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Another phrasing: Perceived time is constant, as if there is a universal time.
I have no idea what you are replying to since you sipped the quote.
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This is why mathematical frameworks such as GR and Quantum are of import. Both are speculations that have been tested by experiment to be relevant. Any further speculation as to how GR and Quantum may be unified would also have to be tested by experiment. Note that speculation comes before experiment. On the basis that GR has passed every test so far, we can use the premise of GR with some degree of confidence in order to further speculate. It is by using the premise of GR that I have further speculated.
Theory is more often driven by observation than by speculation. When scientists do speculate it is from a position of knowledge of theoretical frameworks. The what ifs are informed.
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Timey have a look at state space representation. It is something that could be useful to you. Don't be put off by the fancy sounding name.
https://en.m.wikipedia.org/wiki/State-space_representation
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This is why mathematical frameworks such as GR and Quantum are of import. Both are speculations that have been tested by experiment to be relevant. Any further speculation as to how GR and Quantum may be unified would also have to be tested by experiment. Note that speculation comes before experiment. On the basis that GR has passed every test so far, we can use the premise of GR with some degree of confidence in order to further speculate. It is by using the premise of GR that I have further speculated.
Theory is more often driven by observation than by speculation. When scientists do speculate it is from a position of knowledge of theoretical frameworks. The what ifs are informed.
My what ifs 'are' informed and are posed from a position of knowledge of theoretical frameworks.
Timey have a look at state space representation. It is something that could be useful to you. Don't be put off by the fancy sounding name.
https://en.m.wikipedia.org/wiki/State-space_representation
Thanks for the link. A fancy name does not put me off, but the maths enclosed are quite 'rich'. Can you explain why you believe this to be of import to me for the process of making a consideration concerning particles of mass being attributed gravity potential energy as to their position in a gravity field?
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Look under non linear systems. The pendulum is a gravitationally influenced system. It involves change in elevation and gravitational potential. Depending upon the length of the pendulum there could be marked differences in time dilation along the path of motion. Here you have SR meets GR.
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:Quora
The time perod for simple pendulum is inversely proportional to the square root of acceleration due to gravity.
Time period=2×pie×(l/g)^0.5
And acceleration due to gravity is inversely related to square of the distance from the center of the earth.
g=GM/r^2
Thus, higher the altitude, lesser the acceleration due to gravity, and greater the time period. And it will lose time.
I don't really think that increasing or decreasing the length of a pendulum has anything to do with time dilation. The pendulum clock will 'lose time' at elevation which means it is running slow. This is in contradiction to the GR remit of a clock running faster at elevation.
I think that if we want to look at GR meets SR, then, as I have previously suggested, we should look at the Shapiro effect testing of GR being consistent with SR.
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:Quora
The time perod for simple pendulum is inversely proportional to the square root of acceleration due to gravity.
Time period=2×pie×(l/g)^0.5
And acceleration due to gravity is inversely related to square of the distance from the center of the earth.
g=GM/r^2
Thus, higher the altitude, lesser the acceleration due to gravity, and greater the time period. And it will lose time.
I don't really think that increasing or decreasing the length of a pendulum has anything to do with time dilation. The pendulum clock will 'lose time' at elevation which means it is running slow. This is in contradiction to the GR remit of a clock running faster at elevation.
I think that if we want to look at GR meets SR, then, as I have previously suggested, we should look at the Shapiro effect testing of GR being consistent with SR.
The inputs for the above could equally well be objects falling in a gravitational or alternatively being supported against gravity.
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I'm quite sure these were pertinent consideration over 100 years ago, but since Einstein and other's too numerous to mention have done all the hard work for us? For instance, I don't read about modern experiments testing GR and SR via the simple pendulum. But I do read about experiments testing GR via the Shapiro effect, and I do read about even more modern experiments testing both GR and SR via atomic clocks.
Since the Shapiro testing of GR is consistent with SR, if one was interested in making comparison...this is an obvious avenue for investigation.
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The period of a pendulum depends on the local value of g, so it won't work in deep space, free fall or orbit, where g = 0.
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The period of a pendulum depends on the local value of g, so it won't work in deep space, free fall or orbit, where g = 0.
I think you need to take this onboard...
http://www.yalescientific.org/2010/10/mythbusters-does-zero-gravity-exist-in-space/
But yes - a pendulum would not work in free fall, or orbital free fall. A pendulum that is in deep space, but not in freefall, will hypothetically swing very slowly indeed to the tune of the nearest g-field.
(Btw Alan - I was lucky enough to catch a glimpse of the Red Arrows flying by in formation today. Wonderful sight indeed! Made me think of you...)
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The period of a pendulum depends on the local value of g, so it won't work in deep space, free fall or orbit, where g = 0.
So you've never heard of the deep space pendulum trick?
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What I think it is important to realise is that any photon that is emitted by the clock in the higher potential has been blueshifted by the time it is observed in the lower potential. If you minus the magnitude of the blueshift then the clock isn't ticking faster. General relativity states that the clock is indeed ticking faster.
Very unscientific. What we observe is blue shift, and we observe it to be dependent on gravitational potential difference. Those are the experimental facts. GR is a mathematical model of those facts. It can't "state" anything, but it can and does provide a consistent and accurate prediction "as if" spacetime is warped by gravitation.
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Very unscientific
Cheers!
What we observe is blue shift, and we observe it to be dependent on gravitational potential difference
Could you scientifically tell me from which frame we observe the blueshift from? This being my point. Let me answer that for you. It will be 'from' the lower potential.
Those are the experimental facts
Where the fact is that one will not observe the clock to be emitting blueshifted photons when one is in the higher potential 'with' the faster ticking clock, and the fact is that the mathematical framework of GR predicts that the clock in the higher potential 'is' ticking faster.
The mathematical framework of GR also predicts that the photon emitted by the clock in the higher potential will be gravitationally blue shifted 'by' its change of position 'from' the higher potential 'to' the lower potential, the lower potential being the 'only' frame that one will observe this blueshift from.
So - scientifically speaking Alan, since the mechanism of the clock is reliant upon frequency, and it can only tick faster if the frequency is increased from 9,192,631,770 Hz, can you please explain exactly what frequency of photon is being emitted by the clock in the higher potential?
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Ah groundhog day!
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Ah groundhog day!
Ah yes - An astounding display of scientific expertise there Jeff! I'm nominating you for best physics moderator of the year award.
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I don't know Ken.
I'll cite this though.
"Remember that the intensity of an electromagnetic wave is defined as the wave’s power per unit area. Predictions based on the wave model of light include:
• Light (that is, electromagnetic waves) of any intensity should cause electrons to be emitted. If the intensity is low, it will just take longer for the metal to absorb enough energy to free an electron.
• The frequency of the electromagnetic waves should not really matter. The key factor governing electron emission should be the intensity of the light.
• Increasing intensity means more energy per unit time is incident on a given area, and thus we might expect both more electrons to be emitted and that the emitted electrons would have more kinetic energy.
Amazingly, despite a century of success in explaining many experiments, the predictions of the wave model of light are completely at odds with experimental observations. "
What Planck introduced he himself thought of as a firstly 'mathematical trick'. It was Einstein that put it into context when he used Planck's formula for the spectrum of a black body to introduce the idea of 'photons', finite quanta instead of a wave. No longer a wave but quanta of energy interacting with electrons in that 'black body'.