If light experiences gravitational redshift as said by GR

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Discussion Overview

The discussion revolves around the concept of gravitational redshift as described by General Relativity (GR) and its implications for energy conservation. Participants explore the fate of the energy difference associated with redshift in both gravitational contexts and Hubble expansion.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions where the energy difference associated with gravitational redshift goes, referencing the equation E = hc/λ.
  • Another participant suggests that the energy might be radiated away, though this is presented as a guess.
  • A different perspective proposes that in a simplified scenario of two photons emitted in opposite directions, the energy difference is accounted for by changes in the gravitational field strength, asserting that total energy remains conserved.
  • Another participant speculates that the energy difference could be attributed to "space itself," although this idea lacks further elaboration.
  • One participant introduces the Compton effect and photon momentum, suggesting that energy loss during interactions could contribute to redshift, but expresses uncertainty and indicates a need for further reflection.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the fate of the energy difference associated with redshift, with multiple competing views presented and ongoing uncertainty regarding the explanations offered.

Contextual Notes

Some claims rely on assumptions about energy conservation and the nature of space, while others introduce concepts like the Compton effect without fully resolving their implications for redshift.

Who May Find This Useful

Individuals interested in gravitational physics, cosmology, and the interplay between energy and redshift phenomena may find this discussion relevant.

touqra
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If light experiences gravitational redshift as said by GR, then, where did the difference between the initial and final energy, [tex]E = \frac {hc}{\lambda}[/tex] go?

From Hubble expansion, there is also redshift. Where did the energy difference go?
 
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Radiation? (I'm guessing)
 
where redshift energies go to

In the simplest case (For that ,imagine two equal photons emited in opposite directions from the massive object):In cowering the difference between inital and final gravitational field strenght of the source of the gravity potential.Accompaning mass of the *emitter* before and after changes.Total energy of the system remains conserved of course.


As of from Hubble expansion red shift,and the question: Where did the energy difference go?:I would say nowhere.Only the density of the energy of the Universe should change.No?

cheers
 
I would think that it goes to space itself. (If there is such a thing)
 
E = hc/lamda

when you think of your equation, you notice that the energy is less when the photon of light is emmited back to earth. The reason for this is because of the Compton effect, and photon momentum. Since a photon with energy has a mass, when it strikes an object, some of its energy is lost since the collision is not perfectly ellastic. This would cause a shift to the red side of the spectrum.I think :confused: Let me thisnk about that one for a while, Ill get back to you.
 

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