What happens to the energy lost by photons in gravity?

[PeterDonis]

@Hugh de Launay look at your post #31, which I am purposely not editing. Then look at your post #29, which I edited. Can you see the difference between them? Can you edit post #31 so it looks like post #29?

I don't know why you are having such trouble in properly using the quote system. But you're never going to learn to use it properly if you don't look at what you post and see what's wrong with it, compared to everyone else's posts, and try to fix it.

 

[PeterDonis]

I don't know why you are having such trouble in properly using the quote system.

And, btw, the reason I am making a big deal out of this is that if you don't learn to properly use the quote feature, your posts will be unreadable and nobody will want to respond to you.

 

[Hugh de Launay]

I don't know why you are having such trouble in properly using the quote system

I don't have a good excuse. I am somewhat ignorant in using this type of computer system. Of course you are right about turning people off from reading my input. I think I am close now enough to do a correct post. There may still be some mistakes, but I will preview them and look for ways to correct them with the BBcode guides before I post. Where I screwed up in post #29 and #31, I just had no clue at that time on how to do it right. Now I see what I missed after taking your advise in post #32. Thanks again for your help. You mentors are something special -- being all volunteers.

 

[PeterDonis]

I think I am close now enough to do a correct post.

Your post #34 is fine.

 

[Hugh de Launay]

It definitely depends on either you are a Lagrangian or an Eulerian observer.

Even though it is since Nov. 2, 2018 you posted your comments, I am now responding in case you are still interested. At first I did not understand most of your statements, but I think I understand them now after a little studying, so I will restate what I think you said in my own words.
(1) The Lagrangian observer sees the photon maintain the same wavelength when it is reflected between two mirrors as the mirrors drop down toward a source of gravity. This is because the Lagrangian observer travels alongside the mirrors as they descend. But the immobilized Eulerian observer measures just a short segment of the photon's path on one level and again at a lower level. The observer sees a blue-shift in the photon at the lower level. Without the GR conservation of energy requirement included, the photon has gained energy according to QM.

In other cases such as the expansion of the cosmos, we may say that the gravitational energy that mass gains as the cosmos expands is on the expense of red-shifted photons that reach far observers from the photon source.

In the expansion of the cosmos, the loss of energy during the photon's red-shift is transferred to mass -- an inadequate explanation of dark energy's force which is accelerating the expansion of the universe.

The big picture of conservation cannot be understood from GR alone and physics may have to be updated. After all, physics is a predictive language and language is not reality but a human interpretation of reality.

Conservation laws use higher order derivatives than Noether's first order derivatives in her Lagrangian equations. Conformal gravity mathematics use yet higher order derivatives. QFT uses first order derivatives and makes accurate predictions, through the standard model, that may nevertheless be wrong at Planck scales. New conservation laws will be found at Planck scales. GR is incomplete with respect to the full explanation of energy conservation laws, and physics may have to be developed further to gain a complete explanation of its subject matter.

I have had the good fortune to have heard that all knowledge, including physics and its models, is a virtual reality which can never be the same as what is physically real. For example a five ton tree is not the same as its virtual reality visualization in the three pound human brain.

 

[PeterDonis]

The Lagrangian observer sees the photon maintain the same wavelength when it is reflected between two mirrors as the mirrors drop down toward a source of gravity. This is because the Lagrangian observer tracks the photon along the length of its path.

I'm not sure what you mean by "tracks the photon". The key thing is that the Lagrangian observer is falling with the mirrors.

the immobilized Eulerian observer measures just a short segment of the photon's path on one level and again at a lower level

This is because the Eulerian observer is not falling with the mirrors.

Without the GR conservation of energy requirement included, the photon has gained energy according to QM.

The "GR conservation of energy requirement" is included. The photon has gained kinetic energy according to the Eulerian observer, but it has also lost height and therefore has lost potential energy. The two cancel out; total energy is conserved.

In the expansion of the cosmos, the loss of energy during the photon's red-shift is transferred to mass

No, it isn't. I have no idea where you are getting this from.

Conservation laws use higher order derivatives than Noether's first order derivatives in her Lagrangian equations.

I have no idea where you are getting this from either.

GR is incomplete with respect to the full explanation of energy conservation laws

What do you mean by this?

 

[Hugh de Launay]

This post is a series of responses to Peter Donis's observations in post #36.

I became aware of my misstatement of "tracks the photon" last night and planed to edit a correction into post #35 (which has been accomplished). Peter Donis caught the error also.

Yes, the Eulerian observer does not travel alongside the two mirrors.

I agree that the kinetic energy and the potential energy combined assure the validity of the law of conservation of energy. I excluded this law to emphasize the gain in energy by the photon between the mirrors. This was a restatement in my own words of what I read in post #7.

The red-shift loss of energy must have gone into the energy that expands the cosmos. I must have misstated what I read in post #7.

With respect to the higher order derivatives comments, I was trying to restate in my own words what was stated in post #7. I may not have been successful in doing this.

Again, I was trying to restate in my own words what was stated in post #7.

Thanks for your input Peter Donis.

 

[PeterDonis]

The red-shift loss of energy must have gone into the energy that expands the cosmos.

This is not correct. There is no "energy that expands the cosmos" (apart from dark energy, but the density of dark energy is constant so it doesn't exchange with anything else and can be left out of consideration here). Total energy is not conserved in an expanding universe. You need to go back and read the Sean Carroll article I linked to in post #12.

I must have misstated what I read in post #7.

You did. Post #7 is not saying that what you said is true. It is saying that what you said "sounds rational" but can't be true because such a model doesn't explain what we actually observe.

With respect to the higher order derivatives comments, I was trying to restate in my own words what was stated in post #7. I may not have been successful in doing this.

You're right, you were unsuccessful. I would ignore that part of post #7; it's talking about speculative hypotheses, not about our best current mainstream models.

 

[Hugh de Launay]

read the Sean Carroll article I linked to in post #12.

Thanks for your input. I will read that article.