# Questions tagged [redshift]

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### Would light emitted from a white hole be red-shifted or blue-shifted?

if it's not that straight-forward, what factors would effect the resulting appearance of light emerging from a white hole?
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### Conservation of Charge vs. Conservation of Energy

Is conservation of charge ever violated like conservation of energy is violated during cosmological expansion? I am trying to understand this with respect to Noether's Theorem.
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### Why can we say that $dt_{obs}=(1+z)dt$?

I'm studying how the luminosity of a distant source changes as viewed from an observer far away from it because of the effects of the expansion of the universe. Now, apparently, if a point source ...
57 views

### A violation of energy conservation?

Imagine a universe which contains a single sun and nothing else. The sum of the energy of the univese is then simply the energy contained in the sun and the photons it emits. If I have a theoretical ...
111 views

### Is there any way to differentiate between a redshift caused by recessional motion vs. gravity?

How certain, if at all, are astronomers that the redshift they are measuring is relating to recessional motion as opposed to gravity?
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### Calculating the redshift in cosmological constant dominated universe

How can the redshift be found when $\rho_m = \rho_\Lambda$ and when the cosmological constant begins to dominate from matter? Given that $\Omega_M \approx 0.3$ and $\Omega_\Lambda \approx0.7$ . I've ...
255 views

### Size of the Universe at end of recombination (~477000 years)?

What was the size of the Universe at start of recombination (377000 years) when the Universe started to become transparent and release of trapped photons into what we now know as the CMB and till end ...
454 views

### Finding the cosmological redshift of a galaxy in the expanding Universe

Firstly, I understand what the Doppler effect is when it comes to sound or light waves. From everything that I've read, we are told that the universe is constantly expanding since the all the ...
114 views

### Cause of observed galactic red shift or acceleration in expansion of the universe: velocity vs gravity.

Scientist look out at the universe and observe red shifts for galaxies that are roughly proportionate from their distance from us and attribute it to a velocity away from us. Also there is an ...
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### Is redshift acting on pulses from pulsars and how it changes the diffraction of the pulse and so its brightness?

Is redshift acting on pulses from pulsars and how it changes the diffraction of the pulse and so its brightness? As far as I know the diffraction becomes higher while wavelength increases as moving ...
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### Hubble parameter data from Cosmic Chronometers. Has time dilation been taken into account?

The expansion history of the Universe can found by measuring the differential age evolution of cosmic chronometers. This yields a measurement of the Hubble parameter H(z) as a function of redshift. ...
3k views

### Is it possible to create a mirror that redshifts light?

Mirrors are able to reflect light but are not perfect and after a number of reflections, light loses intensity. However I wonder, during the reflection by a different type of mirror, could the light ...
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### Potential as a function of redshift [closed]

I have a cosmology project where I will plot the potential U as a function of redshift. Is there a formula for this?
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### Cosmology - an expansion of all length scales

From the link Is non-mainstream physics appropriate for this site? "a question that proposes a new concept or paradigm, but asks for evaluation of that concept within the framework of current (...
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### Proof of an accelerated expansion of the universe [duplicate]

Are there any more "proofs" of an accelerated expansion of the universe other than: $1:$ that galaxies that are farther away from us are also more redshifted. $2:$ using "Baryon ...
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### Red shift for an observer outside the gravitational field

Assuming there are no forces around,consider the situation: A multi storey laboratory is accelerating in free space, for convenience say vertically. In it a light pulse is generated. The people in ...
59 views