Question about gravitational redshift

[Rolando]

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

 

I can assure you that in this respect, theoretical physicists are in minority among scientists.

[Strange]

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.

 

If you only use simplified (and therefore largely incorrect) descriptions of models, then you are bound to get confused.

 

You can't extrapolate from these simplified analogies in any meaningful way. You certainly can't argue that because two different analogies seem contradictory that the underlying model must be wrong.

I can assure you that in this respect, theoretical physicists are in minority among scientists.

 

I don't think there is any branch of science where "model" does not mean "mathematical model".

[swansont]

 

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.

 

I reiterate my question about how you measure this and determine where the frequency change occurs.

[xyzt]

 

I can assure you that in this respect, theoretical physicists are in minority among scientists.

You are not a scientist, so you cannot pass valid judgement.

[Rolando]

I don't think there is any branch of science where "model" does not mean "mathematical model".

 

You are right in that models are nearly always used in order to allow a mathematical treatment of a problem.

The difference between theoretical physics and most other branches of science lies in that the former is much more theory-centered, so that "model" is almost synonymous with "theory", while in most other sciences "model" is more often closer to "nature". The models are more phenomenological. Think of medical or psychological research, for instance.

I reiterate my question about how you measure this and determine where the frequency change occurs.

 

I do not quite understand your question. The experiments that have been done have been mentioned, and the two alternatives under discussion differ in where the frequency change is assumed to occur. In alternative (1), the frequency is given at the source and remains unchanged on its way to the receiver. In alternative (2), the frequency changes on the way between source and receiver. Alternative (1) agrees with all observations, but gives rise to my question. Alternative (2) is incompatible with time dilation (in the long run).

 

By the way, these "alternatives" can be considered as different "models".

Edited April 14, 2015 by Rolando

[xyzt]

 

In alternative (1), the frequency is given at the source and remains unchanged on its way to the receiver. In alternative (2), the frequency changes on the way between source and receiver. Alternative (1) agrees with all observations, but gives rise to my question.

No, it doesn't, it suffers a form of frequency shift akin to the Doppler effect. I gave you the exact mathematical description, why do you keep repeating the same fallacy? If what you were saying were true, GPS wouldn't work. Since it works, it means that you keep making the same false claim.

[Rolando]

 

If you only use simplified (and therefore largely incorrect) descriptions of models, then you are bound to get confused.

 

You can't extrapolate from these simplified analogies in any meaningful way. You certainly can't argue that because two different analogies seem contradictory that the underlying model must be wrong.

 

In general, one has to take care that no relevant factor disappears, which can happen if it is not known for sure which the relevant factors are. However, In the present case, the two alternatives (models) under discussion are at least more elaborate than the theory alone. The latter does not tell at all where the effects it predicts arise.

[swansont]

 

I do not quite understand your question. The experiments that have been done have been mentioned, and the two alternatives under discussion differ in where the frequency change is assumed to occur. In alternative (1), the frequency is given at the source and remains unchanged on its way to the receiver. In alternative (2), the frequency changes on the way between source and receiver. Alternative (1) agrees with all observations, but gives rise to my question. Alternative (2) is incompatible with time dilation (in the long run).

.

Assumed being the key. Can you show which one changed, if you are comparing the signal to the oscillator?

 

IOW if you have two clocks that disagree, can you tell if one is fast, or the other is slow?

[Mordred]

Oh man take a spectrum analyzer. We measure the hydrogen line on Earth. It's extremely well known.

 

Then look at the hydrogen line from say our Sun. That known frequency is redshifted. This principle is tested every single day

http://en.m.wikipedia.org/wiki/Hydrogen_line

[MigL]

Time dilation IS the reason for the frequency change between source and observer.

 

And xyzt, you made a valiant attempt at being civil but quickly regressed.

Still it was appreciated by all of us who wish to learn. Thank you.

[Mordred]

Please note this link on Doppler broadening

 

http://en.m.wikipedia.org/wiki/Doppler_broadening

Edited April 14, 2015 by Mordred

[Rolando]

No, it doesn't, it suffers a form of frequency shift akin to the Doppler effect. I gave you the exact mathematical description, why do you keep repeating the same fallacy? If what you were saying were true, GPS wouldn't work. Since it works, it means that you keep making the same false claim.

 

By alternative (1), I mean the alternative that I have called so, and which is that presented by Atkins. If you wish to propose a different alternative, please describe it in words as well. Calling it alternative (1) and accusing me for making false claims is just confusing.

Assumed being the key. Can you show which one changed, if you are comparing the signal to the oscillator?

 

IOW if you have two clocks that disagree, can you tell if one is fast, or the other is slow?

 

This is, of course, impossible. It is clear only in the models (alternatives).

Oh man take a spectrum analyzer. We measure the hydrogen line on Earth. It's extremely well known.

 

Then look at the hydrogen line from say our Sun. That known frequency is redshifted. This principle is tested every single day

http://en.m.wikipedia.org/wiki/Hydrogen_line

 

If you have just two sources, you can't tell for sure which has changed. In the cases you mention, there are lots of additional sources that allow a calibration and also physical reasons that help.

Edited April 14, 2015 by Rolando

[xyzt]

 

By alternative (1), I mean the alternative that I have called so, and which is that presented by Atkins. If you wish to propose a different alternative, please describe it in words as well. Calling it alternative (1) and accusing me for making false claims is just confusing.

 

It is clear that you do not understand what you are posting.

[Mordred]

Why are you constantly missing the mathematics posted?

 

We showed you the related math

 

Try this link

 

http://astro.physics.uiowa.edu/~rlm/mathcad/addendum%2010%20gravitational%20redshift%20and%20time%20dilation.htm

 

Or this review

http://www.maths.tcd.ie/report_series/tcdmath/tcdm1111.pdf

 

Here is another formulation in regards to GPS (might be easier to understand)

 

https://www.aapt.org/doorway/tgrutalks/Ashby/AshbyTalk5of6.htm

Xyzt's metric analysis is bang on the money. His metrics form he used is excellent. To the point where I recorded it in my collection of notes.

Particularly since it's so exacting

[xyzt]

Xyzt's metric analysis is bang on the money. His metrics form he used is excellent. To the point where I recorded it in my collection of notes.

Particularly since it's so exacting

Thank you. One cannot EVER let real science get in the way of fringe misconceptions

Edited April 14, 2015 by xyzt

[Mordred]

 

Here maybe Ashbeys workshop will help it includes good visuals.

 

https://www.aapt.org/doorway/tgrutalks/Ashby/ashbyGRworkshop.pdf

Thank you. One cannot EVER let real science get in the way of fringe misconceptions

No problem I've seen tons of different ways to look at gravitational redshift. I love the format you used

[Strange]

You are right in that models are nearly always used in order to allow a mathematical treatment of a problem.

The difference between theoretical physics and most other branches of science lies in that the former is much more theory-centered, so that "model" is almost synonymous with "theory", while in most other sciences "model" is more often closer to "nature". The models are more phenomenological. Think of medical or psychological research, for instance.

 

While physics is more mathematical than some sciences, there is no branch of science that does not use mathematical models (it wouldn't be science if that were the case).

 

I do not quite understand your question. The experiments that have been done have been mentioned, and the two alternatives under discussion differ in where the frequency change is assumed to occur. In alternative (1), the frequency is given at the source and remains unchanged on its way to the receiver. In alternative (2), the frequency changes on the way between source and receiver. Alternative (1) agrees with all observations, but gives rise to my question. Alternative (2) is incompatible with time dilation (in the long run).

 

You imply that description 2 is incompatible with experimental results. Please provide evidence for this.

 

By the way, these "alternatives" can be considered as different "models".

 

They are not models because they have no mathematics. They are alternative descriptions of the same model.

However, In the present case, the two alternatives (models) under discussion are at least more elaborate than the theory alone. The latter does not tell at all where the effects it predicts arise.

 

Of course they are not "more elaborate". They are gross simplifications with no predictive power.

[Rolando]

Couldn’t you step down from your high horses, so that we can talk on equal footing?
I have no experience in calculations within the frame of GR, of which I have only a superficial knowledge.
I cannot see myself whether any advanced equation presented in this thread is commonplace or innovative.

I do have many years of experience in teaching the scientific method, which involves the use of models,
hypothesis testing, evaluation of theories, etc. to advanced students, whom I encourage to adopt a critical attitude,
perhaps only with moderate success. It is more comfortable to just follow with the stream. However, in my experience,
most of the reviewers of empirical scientific papers expose a similarly critical attitude as I do.

I came to this forum because I noticed deficiencies in both of the ways in which GR is commonly
presented to non-specialists, even to physicists whose focus lies somewhere else. Since I am not

sufficiently knowledgeable within this field myself, I asked a question that might bring light into this affair.
Sure, this identifies me as one of those cranks with a scientific agenda, whom xyzt hates so much.

On the other hand, you do not need to tell me what a model is and similar things, because in this area,

I feel more competent myself.

Edited April 14, 2015 by Rolando

[Strange]

Couldn’t you step down from your high horses, so that we can talk on equal footing?

I have no experience in calculations within the frame of GR, of which I have only a superficial knowledge.

I cannot see myself whether any advanced equation presented in this thread is commonplace or innovative.

 

In that case, it seems you will just have to accept the word of those who can do the maths (not me, by the way ) when they tell you that these two descriptions are simply different views of the same model.

 

If you want to argue that is not the case, then you will have to come back when you have mastered the maths.

 

Would you tell your surgeon that all his years of study are wasted because you don't think the simple descriptions you read in a newspaper make sense?

[xyzt]

Couldn’t you step down from your high horses, so that we can talk on equal footing?

I have no experience in calculations within the frame of GR, of which I have only a superficial knowledge.

 

Then, you have no foot to stand on. The language of the ENTIRE physics, not only GR is math. You don't know the math, you have no valid argument. Period.

[Phi for All]

Couldn’t you step down from your high horses, so that we can talk on equal footing?

I have no experience in calculations within the frame of GR, of which I have only a superficial knowledge.

I cannot see myself whether any advanced equation presented in this thread is commonplace or innovative.

!

Moderator Note

You're in the mainstream science sections. We have a Speculations section if you'd like to challenge accepted theories, but here the replies are going to reflect our best current explanations, many of which only make sense if you speak math.

 

We make the assumption that if you're posting in Relativity, you want to discuss Relativity with people who know what they're talking about. All are trying to help, some are abrasive, most are not.

[Rolando]

 

In that case, it seems you will just have to accept the word of those who can do the maths (not me, by the way ) when they tell you that these two descriptions are simply different views of the same model.

 

If you want to argue that is not the case, then you will have to come back when you have mastered the maths.

 

I do have a sufficient understanding of what these two descriptions are about, and the math is not the problem at this level.

 

I do not argue about the maths, and you are right in that I have just to accept what the experts say when it becomes more advanced. I argue about the descriptions. To me, they cannot be simply different views of the same model. One of them, I can see as representative of the model Einstein used in 1911. If it is claimed to be a description of GR, this is severely misleading. The other one is adequate to GR, but it rises my question.

Edited April 14, 2015 by Rolando

[Strange]

I do not argue about the maths, and you are right in that I have just to accept what the experts say when it becomes more advanced. I argue about the descriptions. To me, they cannot be simply different views of the same model. One of them, I can see as representative of the model Einstein used in 1911. The other one is adequate to GR, but it rises my question.

 

If you are unable to do the maths, how can you say that a description does not match the mathematics? You can only rely on your "gut feeling". And that is obviously misleading you. So you have to learn not to trust it.

[Rolando]

!

Moderator Note

You're in the mainstream science sections. We have a Speculations section if you'd like to challenge accepted theories, but here the replies are going to reflect our best current explanations, many of which only make sense if you speak math.

 

We make the assumption that if you're posting in Relativity, you want to discuss Relativity with people who know what they're talking about. All are trying to help, some are abrasive, most are not.

 

I do not speculate. Nor do I challenge accepted theories. I just ask a question that involves no more than the simplest equation for gravitaional time dilation and redshift.

[Strange]

 

I do not speculate. Nor do I challenge accepted theories. I just ask a question that involves no more than the simplest equation for gravitaional time dilation and redshift.

 

And the equation is identical for both descriptions.