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Originally Posted by Kharakov
Hi modest,
The redshift / expansion relationship remains intact in the scenario (larger recession velocity = larger redshift). Metric expansion redshift is due to the recession velocity of the body the photon is moving towards.
In the scenario proposed, expansion redshifts are not eliminated (they remain the same). However, the wavelengths of the photons (and/or particles) are smaller in proportion to the size of space itself (more space + same wavelength photon = photon has smaller wavelength to space size ratio).
To be clear, a photon's wavelength does not actually change in transit, rather it is the recession velocity of the observer that redshifts the photon.
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My understanding is that you can model redshift as recession with one coordinate choice or you can model it with expanding space with another coordinate choice. Essentially: either galaxies are redshifted because they have a recession velocity or they are redshifted because space between them expands. I don't see how you could apply both.
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What Causes the Hubble Redshift? Are the light waves "stretched" as the universe expands, or is the light doppler-shifted because distant galaxies are moving away from us?
In a word: yes. In two sentences: the Doppler shift explanation is a linear approximation to the "stretched light" explanation. Switching from one viewpoint to the other amounts to a change of coordinate systems in (curved) spacetime.
What Causes the Hubble Redshift?
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Ned Wright's cosmology tour explains that the distance and time in Hubble's law is not the same thing as the distance and time in special relativity. It shows two spacetime diagrams of a low density universe with each coordinate choice saying:
~modest
