Questions tagged [redshift]
Redshift refers to the difference in frequency of an electromagnetic wave as measured by a source versus a receiver in relative motion.
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Do blueshifted and redshifted light sources have differing energies?
The thought experiment:
Two spaceships are passing each other some distance from a star. Both ships are at relativistic speed, one toward and one away from the star. Should the total energy observed ...
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Could some objects survive Big Bounce e.g. now seen with these extreme redshifts by JWST?
There are recent claims for observations of up to redshift 25 objects by JWST, which are said too early to be formed by standard Big Bang models, e.g. https://www.scientificamerican.com/article/the-...
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Where does the energy go when light redshifts? [duplicate]
Consider a source of light emitting radiation towards an observer. If it is stationary, then the frequency of the emitted and observed radiation is the same. But consider when it moves away from the ...
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How was Hubble's Law found?
I'm surprised that the result $v=H_0r$ is so simple, even though we need to consider the Doppler Effect and gravitational redshift from redshift data.
Any related material about the deduction from ...
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Confusion about the relationship between redshift and dark energy
Currently, in cosmology, dark energy is inferred from the observation that the space between galaxies is expanding at an accelerating rate. This is why Type Ia supernovae appear dimmer than expected, ...
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Redshift is too uniform for the tired light model
Astrophysicists say that redshift is too uniform for the tired light model to be true. Can anyone explain this and refer to a paper discussing this question?
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About the relativistic Doppler redshift and Lorentz transformation
I'm learning the relativity with A First Course in General Relativity, Bernard Schutz.
In the last section of Chapter 2, the author derived the relativistic redshift formula
$$\dfrac{\bar{\nu}}{\nu} = ...
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Is Cosmological redshift a composite redshift?
Must the cosmological redshift z, which is fundamental to the expansion of the universe and the Hubble Law, be considered a genuine and specific magnitude, or can it be constructed mathematically as a ...
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Is the universe “leaking” energy? [duplicate]
Note that english is not my first language, please forgive me for any grammatical error
We know that the universe is expanding. This expansion causes photons (of energy $E = h \nu$) emitted from a ...
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Red Shift Uncertainties
From a very amateur astronomer seeking enlightenment: I often read that "red shift" proves the universe is expanding and that the farther away the source, the more red-shifted and therefore ...
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Why is redshift possible if the speed of light is constant?
In high school, it is explained to students that the Doppler effect causes the frequency of sound waves to increase during motion towards the sound source, and decrease when moving away.
This ...
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Covector Wave Fields and Gravitational Redshift
I'm currently deriving the gravitational redshift in the Schwarzschild spacetime by following Wald's dicussion on the topic.
I came across this video, which talks about the gravitational redshift ...
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When will the CMB reach radio wavelengths?
How long will it take for redshift to turn the microwave-frequency photons from the CMB into radio frequency? Into the CRB, if you will.
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In cosmology, how to calculate redshift from position and velocity?
As part of a computation in the context of Cosmology, I have the position and velocity of a galaxy in Cartesian coordinates, and I would like to find out its total redshift. In order to do this there ...
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Did I find calculation errors in the paper "Expanding Confusion"?
There's an excellent paper that I've read a few times called "Expanding Confusion" (2004) by Davis and Lineweaver that explains the variety of cosmic horizons quite well. Link to it here.
In ...
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Conservation of energy in cosmological redshift
When light is released from a faraway star (that is, most noticeably a faraway star), the wavelength is stretched due to the expansion of the universe. The photons/light wave lose energy in that ...
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Can light blueshift from gravity assists?
I'm aware that light can redshift when escaping from a gravity well, and that it can blueshift when entering a gravity well of the observer. But is it also possible for light to blueshift from '...
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Velocity to put into relativistic doppler effect with expansion of universe
It is well known that there are few kinds of redshifts (e.g. relativistic, cosmological, gravitational).
And the formulas are
\begin{align}
1+z_\mathrm{rel}&=\sqrt{\frac{1+v/c}{1-v/c}}\,\,\text{(...
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Energy of photons in perfect mirror box with FRW metric
In FRW metric, distance is described by
\begin{align}
ds^2 = dt^2 - a(t)^2[d\chi^2 + S_k(\chi)^2 d\Omega^2]\\
=dt^2 - a(t)^2\gamma_{ij}dx^i dx^j
\end{align}
where $a$ is the scale factor.
Now by using ...
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Doppler Effect and the concept of relative velocity in GR
While reading Sean Carroll's book on General Relativity, I understood that the concept of velocity is ill-defined over large distances in arbitrarily curved manifolds, like the one used to describe ...
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Factor for observed redshift - light dispersion (chromatic aberration) caused by a gravitational lensing
This thought tortured me for a while now, and I can't find if this has been hypothesized/discussed before, and if so, is there a consensus:
Can redshift be to at least some degree a result of a ...
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Distance needed for visible light to be cosmologically redshifted to microwave
What distance will it take for visible light to become a microwave due to cosmological redshift?
I'm not sure how to calculate this, as I'm never good at complex math. I tried googling but didn't find ...
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$I_{\nu}/\nu^{3}$ which is Lorentz invariant is also invariant for cosmological redshift?
$I_{\nu}/\nu^{3}$ is Lorentz invariant, therefore an observed intensity is boosted by $\delta^{3}$, where $\delta$ is the Doppler factor. If the cosmological redshift is same physical process with ...
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Redshift of the CMB
Has the $z\sim 1100$ redshift of the CMB been actually measured by comparing the fingerprint (absorption spectrum) of the CMB with the theoretical radiation pattern of a $2.725\,\mathrm{K}$ blackbody, ...
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In a fast moving space ship, can you harvest energy from the radiation background?
In a fast moving space ship (let's say a meaningful portion of c), radiation coming from the front is blue-shifted, while the one coming from behind is red-shifted. Meaning the part of the universe ...
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