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What's the definitive meaning of "redshift", as a quantity to be measured?

In spectroscopy, the term redshift is very often loosely used as well, as shorthand for “we observe the peak at longer wavelengths”. For UV-VIS this makes sense, but it actually confused me when I ...
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What's the definitive meaning of "redshift", as a quantity to be measured?

Redshift refers to a change in observed frequency (to a lower frequency) of any kind of wave, that is, when there is a difference between the frequency of a wave at the origin (where the wave is ...
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What's the definitive meaning of "redshift", as a quantity to be measured?

It's usually electromagnetic, but it can be seen either in the frequency of the light or the frequency of pulses of light. The latter is used to infer orbits for binary pulsars. Gravitational waves ...
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How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other?

Gravity field is an area where optical density of space is higher than that of empty space. Gravity field is an area where refractive index of space is higher than one. So here is a video about light ...
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How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other?

How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other? There is a basic misunderstanding here. It is classical electromagnetic radiation ...
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How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other?

How can gravity change the wavelength of a photon without the two peaks or troughs to accelerate one from the other? So is it possible that gravity accelerates light? Yes. In general relativity the ...
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How do we observe redshifted light from distant stars if the effect is not intrinsic to photons?

Given an event in spacetime with light going through it, you can make that light seem to have any wavelength by choosing the right freefalling observer. Remember that freefalling observers at the same ...
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How do we observe redshifted light from distant stars if the effect is not intrinsic to photons?

For gravitational redshift in particular, we are approximately a stationary observer at infinity with respect to the distant star's emitted photons. So we observe the redshift because of our location ...
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Cosmological energy conservation

No. The energy of photons lost to cosmological redshift may be paid for by the photons' increased gravitational potential energy as measured by the frame that measures both the redshift and the ...
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