Question about gravitational redshift

[Rolando]

 

Certainly - like all reputable scientists they had no bias and were certainly disinterested; but again like all good scientists they were very keen to learn about the world. and were certainly interested in GR. Interested enough to set up an experiment that seems to most to be the last of the classical tests of GR proposed by Einstein

I do not quite agree. They explicitly worked on the basis of Einstein (1911), which they showed to agree with their result. It reflects wishful thinking to interprete their experiment as test of GR, which merely predicts the same result (if the experiment is performed above ground level, as it was).

Edited April 12, 2015 by Rolando

[xyzt]

 

 

This paper by A. Sfarti describes a proposal – not an actually performed experiment, and it is written by an author who shows no awareness of the difference between GR and Newtonian physics. [

LOL.

 

 

 

This is clear already in the first clause of the Abstract, which reads ”Einstein predicted a change in the energy of photons in the proximity of a gravitational field, the change being directly proportional to the distance from the gravitational source.” This is true of Einstein (1911),

 

Your crackpot index just jumped 100 points.

 

 

 

 

but nowadays everybody associates Einstein in this context with GR (1916), and in GR, it is not true! [in GR, there is a difference in energy but no change.] Actually, Pound and Rebka reasoned similarly. They were not concerned with GR either. They referred only to Einstein (1911).

 

Yet another 100 points on the crackpot scale.

 

 

 

 

 

Although Sfarti proposes a mineshaft experiment of the kind I asked for, he fails to see its potential of falsifying one of the theories.

 

Which theory? The paper is about the GR explanation of the proposed experiment, not about falsifying any theory. You just earned yourself an additional 50 points on the crackpot scale.

 

 

 

 

The paper is written in Newtonian terms. In GR, the equations involving the gravitational potential that appear at the beginning of the paper are only valid above the surface of the Earth.

 

Err,no. You are totally ignorant on the subject, the formalism is the Schwarzschild formalism, meaning it IS GR. Take another 50 points on the crank index.

 

 

 

 

If GR is correct, the result of the experiment will disagree sharply with the presented prediction.

 

Prove it. In the meanwhile, take another 100 points on the crank scale.

 

 

 

The math that shows the predictions of the Newtonian theory as elaborated by Einstein (1911) can be found in the papers by Pound & Rebka and by Sfarti.

 

Repeating the same crank ideas doesn't make them right. Yet another 100 points.

 

 

 

I wanted to be a little funny, but having had a quick look at several papers by Pound & Rebka again, I am left with the impression that they were just disinterested in GR.

 

This is worth 200 points on the crackpot index.

 

 

 

 

Let me try it:

 

In GR, the photon frequency shift is approximately (ν_e – ν_o)/ν_o = gh/c², where h is the diffence between the upper and the lower level.

 

Yes. The first thing that you copied correctly.

 

 

 

 

This holds in practical approximation also below the surface of the Earth (inserting the g-value that holds in the middle between the two levels).

 

No, it doesn't, there is a difference that is caused by the difference in the potential formula (or by the difference between the external and the internal Schwarzschild solutions). Take another 50 crank points.

 

 

 

In Einstein’s Newtonian approach, the same equation holds above the surface of the Earth.

 

"Einstein Newtonian approach"? This is worth a whopping 300 crackpot points.

 

 

If the Earth was a non-rotating spere of uniform density, this would be turned into (ν_e – ν_o)/ν_o = –gh/c² below the surface.

 

Now you are way off in lala land, the formula for the potential inside the Earth is different than the external formula, you can't simply invert the sign . Prove your ASSertion, In the meanwhile, here is another 200 points on the crank index.

 

OK, you can tally your total but you can easily see that your crankiness is off the charts.

Edited April 12, 2015 by xyzt

[Rolando]

You obviously do not understand what you are reading. Can you copy and paste the exact citation?

LOL.

 

Your crackpot index just jumped 100 points.

 

Yet another 100 points on the crackpot scale.

 

You just earned yourself an additional 50 points on the crackpot scale.

 

Take another 50 points on the crank index.

 

In the meanwhile, take another 100 points on the crank scale.

 

Yet another 100 points.

 

This is worth 200 points on the crackpot index.

 

Take another 50 crank points.

 

This is worth a whopping 300 crackpot points.

 

In the meanwhile, here is another 200 points on the crank index.

 

OK, you can tally your total but you can easily see that your crankiness is off the charts.

 

Do you really believe that this kind of argumentation is convincing?

Especially if it comes from somebody who tells me that I do not understad what I am reading and only afterwards asks me for the text in question?

If you wish to tell me where you think that I went wrong in my reasoning, please do so - but without adding rubbish like this.

Edited April 12, 2015 by Rolando

[xyzt]

 

Do you really believe that this kind of argumentation is convincing?

Actually, I DID point out your errors. On the other hand I never managed to convince a crank that he's a crank. This is why the crank is a crank.

Edited April 13, 2015 by xyzt

[Rolando]

Actually, I DID point out your errors. On the other hand I never managed to convince a crank that he's a crank. This is why the crank is a crank.

My rhetorical question was about the contribution of the quoted utterances to the topic under discussion. Not about your definition of a ”crank”.

 

No, it doesn't, there is a difference that is caused by the difference in the potential formula (or by the difference between the external and the internal Schwarzschild solutions). Take another 50 crank points.

According to my limited knowledge, the internal Schwarzschild solution applies inside the event horizon of black holes. Does it really apply below the surface of the Earth or did you happen to confuse the Earth with a black hole?

Edited April 13, 2015 by Rolando

[xyzt]

 

 

According to my limited knowledge, the internal Schwarzschild solution applies inside the event horizon of black holes. Do you consider the Earth a black hole?

False, applies to ANY spherical gravitating body. And it is not inside the EH, it is inside the body proper. So, you are 0 for 2. Look, stop making up stuff, take a class, you will be gaining a lot this way.

Edited April 13, 2015 by xyzt

[Mordred]

Actually the Shwartchild metric applies to all objects. Any particle or body that compresses below its Schwartchild metric can form a BH.

[xyzt]

Actually the Shwartchild metric applies to all objects. Any particle or body that compresses below its Schwartchild metric can form a BH.

Schwarzschild. Radius, not metric. In addition, the gravitating body must start with a minimum mass.

[Mordred]

 

 

You also didn't make the connections between Doppler to relativistic Doppler and gravitational redshift. Cosmological redshift also applies the rules of GR. So does gravitational redshift.

 

All three forms of redshift is connected the main difference between them is choice of observer and coordinate system used. Fundamentally all three are forms of Doppler/relativistic Doppler.

Schwarzschild. Radius, not metric. In addition, the gravitating body must start with a minimum mass.

Ah right lol

[Rolando]

False, applies to ANY spherical gravitating body. And it is not inside the EH, it is inside the body proper.

 

So, you are 0 for 2. Look, stop making up stuff, take a class, you will be gaining a lot this way.

The text on the first line is the kind of response that is valuable to me. Thanks for it.

The rest is just annoying rubbish.

Edited April 13, 2015 by Rolando

[xyzt]

The text on the first line is the kind of response that is valuable to me. Thanks for it.

The rest is just annoying rubbish.

Actually, the "rest" is more valuable. You clearly do not know what you are talking about and you are making up stuff. Anyone educated in the field can see that. You would gain a lot more from taking a class than wasting your time posting made up stuff on forums.

[Strange]

Only alternative (1) predicts a general time dilation. Alternative (2) does not predict clocks further down in a gravitational well to appear to be slow. Instead, it predicts periods of the radiation to be lost on its way up.

 

Neither of them predicts anything; they are just alternative ways of describing the predictions of GR.

[swansont]

There is no difference between these, but in Newtonian theory the photon frequency change is not matched by a corresponding difference in elapsed time at the two places.

 

It isn't in GR, either. GR says there is a relative shift between the two.

[MigL]

Whether the gravitational red shift is due to time dilation in a frame deeper in the gravitational well, or to radiation losing energy as it climbs out of the gravitational well, is moot.

We can only ever measure the time dilation by the radiation signal in our frame. And that shows that the signal has lost energy climbing out of the well.

 

And I find it rich that xyzt previously complained about swansont 's response ( " You don't have to get rude " post #11 ), yet everyone of his, while accurate and true to the math ( if not the physicality ), is disparaging and condescending.

I give you the same advice you gave to Rolando.Take a few courses on dealing with people.

WE are not doing physics here. None of this will get published, or quoted in papers.

What we are doing is discussing and dealing with people.

Edited April 13, 2015 by MigL

[Phi for All]

LOL.

 

 

 

 

Your crackpot index just jumped 100 points.

 

 

 

 

 

Yet another 100 points on the crackpot scale.

 

 

 

 

 

 

Which theory? The paper is about the GR explanation of the proposed experiment, not about falsifying any theory. You just earned yourself an additional 50 points on the crackpot scale.

 

 

 

 

 

Err,no. You are totally ignorant on the subject, the formalism is the Schwarzschild formalism, meaning it IS GR. Take another 50 points on the crank index.

 

 

 

 

 

Prove it. In the meanwhile, take another 100 points on the crank scale.

 

 

 

 

Repeating the same crank ideas doesn't make them right. Yet another 100 points.

 

 

 

 

This is worth 200 points on the crackpot index.

 

 

 

 

 

Yes. The first thing that you copied correctly.

 

 

 

 

 

No, it doesn't, there is a difference that is caused by the difference in the potential formula (or by the difference between the external and the internal Schwarzschild solutions). Take another 50 crank points.

 

 

 

 

"Einstein Newtonian approach"? This is worth a whopping 300 crackpot points.

 

 

 

Now you are way off in lala land, the formula for the potential inside the Earth is different than the external formula, you can't simply invert the sign . Prove your ASSertion, In the meanwhile, here is another 200 points on the crank index.

 

OK, you can tally your total but you can easily see that your crankiness is off the charts.

 

!

Moderator Note

Knock off the personal comments. Restrict your comments to the ideas proposed, or don't participate. You know the rules.

[xyzt]

WE are not doing physics here. None of this will get published, or quoted in papers.

What we are doing is discussing and dealing with people.

I'll have to agree, you aren't doing any physics. I , on the other hand, am.

I pointed out his errors , using mainstream physics. This means doing physics.

Edited April 13, 2015 by xyzt

[MigL]

Most of us are here to learn and teach.

Your math skills are way above mine, but no-one is an expert in everything.

You could certainly be a teacher to a lot of us with regards to math, but you, yourself, realize that you're no 'Mr. Congeniality", as you describe yourself as a 'curmudgeon'.

 

A little more teaching and less put-downs would be appreciated.

 

Not a request or order by any means, just a suggestion.

[xyzt]

Most of us are here to learn and teach.

Your math skills are way above mine, but no-one is an expert in everything.

You could certainly be a teacher to a lot of us with regards to math, but you, yourself, realize that you're no 'Mr. Congeniality", as you describe yourself as a 'curmudgeon'.

 

A little more teaching and less put-downs would be appreciated.

 

Not a request or order by any means, just a suggestion.

Yes, I could be more congenial. A few things that you need to be aware of:

 

1. I did not describe myself as 'curmudgeon'. the administrators did

2. I am congenial with the people that really want to learn, it is the cranks with an agenda that annoy me.

3. Lately, this forum has seen a true infestation by the latter category.

 

So, just you know...

[Rolando]

 

Neither of them predicts anything; they are just alternative ways of describing the predictions of GR.

Well, it is the theory that predicts things, but the two alternatives seem to put restrictions on the theory.

 

It isn't in GR, either. GR says there is a relative shift between the two.

Let me skip this. There may be a misunderstanding invlolved here, but I do not think we are in disagreement.

 

Whether the gravitational red shift is due to time dilation in a frame deeper in the gravitational well, or to radiation losing energy as it climbs out of the gravitational well, is moot.

We can only ever measure the time dilation by the radiation signal in our frame. And that shows that the signal has lost energy climbing out of the well.

 

There is clear experimental evidence for the existence of a frequency difference and the consequent difference in signal power or photon energy between identical radiation sources at different levels and there is also clear evidence for a difference in the readings of clocks at different levels, which even needs to be taken into consideration in the GPS and in other satelite systems. This means that the problem we discuss is not just an “academic” one.

 

Let me restate my original question with slight modifications. The gravitational redshift is described in the literature mainly in two ways:

 

(1) the phenomenon is explained through the behaviour of atoms that emit radiation of lower frequency (or clocks that run more slowly) the deeper they are located in a potential well, while the frequency of the light (or photons) does not change on its way to a different height. This kind of description is found in basic textbooks, such as “Physics” by Kenneth R. Atkins, of which I possess a version in German. It is illustrated in http://en.wikipedia....tional_redshift [see the colorful illustration there and compare it with Abbildung 25-14 (b), above]. If alternative (2) were true, there would be no time dilation, i.e, clocks closer to an attractive body would not be observed to be slow (in the long run).

 

While alternative (2) is incompatible with GR, alternative (1) seems to me to be incompatible with the idea behind GR as well.

 

According to GR, time is dilated in gravitational wells, and this is an effect of the curvature of space-time. However, if this is so, then why is the light itself not affected by this curvature? If it was affected to the same extent as the atoms, the gravitational frequency shift would be zero, and if it is necessary to assume that light propagates through a different space-time, this is very much in need of a logical explanation.

 

The alternatives (1) and (2) cannot be applied together, since in this case the gravitational frequency shift would turn out to be twice as high as observed and predicted by GR.

 

I think that nothing of essential import has come forward in the discussion. My question remained unanswered. However, a further alternative has been briefly mentioned:

 

(3) The phenomenon might be interpretable as Doppler shift. In this case, there can be no discrepancy between frequency shifts and time dilation. I have not yet read the relevant paper.

 

 

 

Edited April 13, 2015 by Rolando

[xyzt]

 

According to GR, time is dilated in gravitational wells, and this is an effect of the curvature of space-time. However, if this is so, then why is the light itself not affected by this curvature? If it was affected to the same extent as the atoms, the gravitational frequency shift would be zero, and if it is necessary to assume that light propagates through a different space-time, this is very much in need of a logical explanation.

 

 

All electromagnetic radiations are affected EQUALLY. So, you can stop beating the strawman "light itself is not affected by this curvature". One of the tenents of logic is that , if you start with garbage assumptions, you can end up with any conclusions, in most cases garbage as well.

Here is the standard proof:

 

All periodical processes are affected equally by gravitation. Start with the Schwarzschild solution to the EFE's:

 

[math](cd\tau)^2=(1-r_s/r)(cdt)^2-dr^2/(1-r_s/r)-(rd\theta)^2[/math]

 

For two periodical processes located at Schwarzschild radial coordinates [math]r_1[/math] and [math]r_2[/math] one can write:

 

[math](cd\tau_1)^2=(1-r_s/r_1)(cdt)^2-dr^2/(1-r_s/r_1)-(r_1d\theta)^2[/math]

 

[math](cd\tau_2)^2=(1-r_s/r_2)(cdt)^2-dr^2/(1-r_s/r_2)-(r_2d\theta)^2[/math]

 

Dividing the two one gets, expressed in clock periods:

 

[math]\frac{d\tau_1}{d\tau_2}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(r_1/cd\theta/dt)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(r_2/cd\theta/dt)^2}}[/math]

 

Most often, the above is expressed in terms of frequencies :

 

[math]\frac{f_2}{f_1}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(r_1/cd\theta/dt)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(r_2/cd\theta/dt)^2}}[/math]

 

 

The above is the general equation that governs the functionality of GPS, so, its validity is confirmed on a daily basis, every second of it. The above also represents the most rigorous explanation of the Pound-Rebka experiment since it factors in not only the difference in altitude but also the difference in tangential speeds.

 

[math]\frac{f_2}{f_1}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(v_1/c)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(v_2/c)^2}}[/math]

 

With a little effort, I can show you how the above explains the Hafele-Keating experiment (one needs to execute an integral wrt. coordinate time)..

Edited April 13, 2015 by xyzt

[Strange]

Well, it is the theory that predicts things, but the two alternatives seem to put restrictions on the theory.

 

Only if you try and take these descriptions (which are, ultimately, just analogies) too literally.

[Rolando]

All electromagnetic radiations are affected EQUALLY. So, you can stop beating the strawman "light itself is not affected by this curvature". One of the tenents of logic is that , if you start with garbage assumptions, you can end up with any conclusions, in most cases garbage as well.

Here is the standard proof:

 

All periodical processes are affected equally by gravitation. Start with the Schwarzschild solution to the EFE's:

 

[math](cd\tau)^2=(1-r_s/r)(cdt)^2-dr^2/(1-r_s/r)-(rd\theta)^2[/math]

 

For two periodical processes located at Schwarzschild radial coordinates [math]r_1[/math] and [math]r_2[/math] one can write:

 

[math](cd\tau_1)^2=(1-r_s/r_1)(cdt)^2-dr^2/(1-r_s/r_1)-(r_1d\theta)^2[/math]

 

[math](cd\tau_2)^2=(1-r_s/r_2)(cdt)^2-dr^2/(1-r_s/r_2)-(r_2d\theta)^2[/math]

 

Dividing the two one gets, expressed in clock periods:

 

[math]\frac{d\tau_1}{d\tau_2}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(r_1/cd\theta/dt)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(r_2/cd\theta/dt)^2}}[/math]

 

Most often, the above is expressed in terms of frequencies :

 

[math]\frac{f_2}{f_1}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(r_1/cd\theta/dt)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(r_2/cd\theta/dt)^2}}[/math]

 

 

The above is the general equation that governs the functionality of GPS, so, its validity is confirmed on a daily basis, every second of it. The above also represents the most rigorous explanation of the Pound-Rebka experiment since it factors in not only the difference in altitude but also the difference in tangential speeds.

 

[math]\frac{f_2}{f_1}=\sqrt{\frac{1-r_s/r_1-(dr^2/(cdt)^2)/(1-r_s/r_1)-(v_1/c)^2}{1-r_s/r_2-(dr^2/(cdt)^2)/(1-r_s/r_2)-(v_2/c)^2}}[/math]

 

With a little effort, I can show you how the above explains the Hafele-Keating experiment (one needs to execute an integral wrt. coordinate time)..

Thanks for your effort. Unfortunately, it does not answer my question. I did not ask about how to calculate the effects, and I have told that they have all been observed. Your equations are perfectly in agreement with alternative (1), which gave rise to my question. In order to answer it, it is necessary to talk about the model, not the math. Where do the effects arise in the model or in the real world along the line between source and receiver, including these themselves?

 

By the way, how can it be that you were not aware of the fact that alternative (1) used to be widely tought, (at the level of Atkins' book)?

 

Maybe you can also tell us why alternative (2) has gained popularity in the past 20 years or so?

Isn't it clear that it involves a loss of periods, and so is in conflict with time dilation (clock retardation)?

How is this conflict resolved?

 

Edited April 13, 2015 by Rolando

[xyzt]

Thanks for your effort. Unfortunately, it does not answer my question.

Of course it doesn't, if it did, it would be reason for you to cease trolling. And you can't allow this to happen, you need to keep posting ad nauseaum.

 

 

 

In order to answer it, it is necessary to talk about the model, not the math.

 

Were you aware that the model IS the math? No?

 

 

 

Maybe you can also tell us why has alternative (2) has gained popularity in the past 20 years or so?

 

Fact is that it HASN'T. So, you can stop beating the poor strawman. The explanation I gave you is the standard, contemporary explanation for : GPS, gravitational time dilation (Pound Rebka), "twins paradox" or differential total elapsed proper time (Hafele-Keating, Vessot).

Edited April 13, 2015 by xyzt

[Rolando]

Of course it doesn't, if it did, it would be reason for you to cease trolling. And you can't allow this to happen, you need to keep posting ad nauseaum.

 

I do not understand what "trolling" means. I find only "troll" in my English dictionary, but it makes no sense here.

 

However, the remainder of your utterances tells me that this is just another load of the rubbish you need to keep throwing at people ad nauseam.

 

From your previous posting, I got the impression that you might now be ready to contribute to this discourse in a civilized manner. I regret that I was in error.

Were you aware that the model IS the math? No?

 

I am aware that this is often so when theoretical physicists talk about a model. But here, it was me who used the word, and I am not a theoretical physicist. For me, a model is a simplified representation of reality that keeps only the aspects that are relevant in the context in question.

[xyzt]

 

I am aware that this is often so when theoretical physicists talk about a model. But here, it was me who used the word, and I am not a theoretical physicist. For me, a model is a simplified representation of reality that keeps only the aspects that are relevant in the context in question.

Ignorance is no excuse, you don't get to make up your own terms, at odds with mainstream science.