Cosmological redshift: how much energy has gone missing?

In summary, the conversation is discussing the phenomenon of cosmological redshift and the question of what happens to the energy of photons in this process. Some suggest that the energy is lost, while others speculate that it may go somewhere, such as fueling dark energy. Rough estimates are provided for the amount of energy lost from the CMB due to redshift and it is noted that this is roughly equal to the current density of dark energy. The number of CMB photons per unit volume of space is also calculated.
  • #36
Originally posted by schwarzchildradius
as long as you have no problems with infinite energy existing in an infinitely small volume, then physics has no problem describing the conditions of t=0.

Are you still discussing John Baez's essay
"the Meaning of Einstein's Equation"?

http://math.ucr.edu/home/baez/einstein/einstein.html

It has 9 pages linked together and he calls it "a brief introduction to General Relativity." I still go back over certain pages from time to time because it is a masterful job of making an honest presentation of the mathematics short and understandable.

I suggested you look at page 2 , "Preliminaries".

I can't tell what you are discussing. It does not seem to be page 2.

On many of the pages (not page 2 but others) he uses "t=0"
to stand for some normal reference time, like the present, after the universe is well on its way and evolving normally. Think of it as noon GMT on March 1----some arbitrary time zero. In no case does he use "t=0" to refer to a singularity. Nothing in the essay concern infinite densities. So it has been four days now since I suggested the essay to you and it clearly has not helped you.
I'm not clear about why. But probably means I shouldn't recommend online physics links to you.
 
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  • #37
You've got a weird attitude. That particular link has been discussed on PF last year. In any case, t=0 refers to the singularity at the beginning of time. If you have a solution/explanation for this, we would all love to hear of it!
 
  • #38
Originally posted by schwarzchildradius
You've got a weird attitude. That particular link has been discussed on PF last year. In any case, t=0 refers to the singularity at the beginning of time. If you have a solution/explanation for this, we would all love to hear of it!

The explanation is simple, in Baez essay t=0 nowhere refers to the beginning of time. You totally failed to come to grips with the meaning of his essay, if you think that.
His essay is called "The Meaning of Einstein's Equation"
If there is anyone still at the board who took part in
a discussion "on PF last year" of that online essay, I invite
you to ask them if t=0 means the beginning of time
in that essay. If anyone thinks that, they totally failed to
grasp the equations and should go see a mentor like Tom
or damgo.

I am sorry but I don't feel I should spend any more time on this.
I am not sure I am getting a straight story from you, what with the "physics breaks down" business which was not in Baez essay and our failure to connect about the meaning of basics like the timescale. Adios. Bye.
 
<h2>1. What is cosmological redshift?</h2><p>Cosmological redshift is the phenomenon where light from distant objects in the universe appears to be shifted towards the red end of the electromagnetic spectrum. This is due to the expansion of the universe, which stretches the wavelengths of light as it travels through space.</p><h2>2. How is cosmological redshift related to the missing energy in the universe?</h2><p>The missing energy in the universe refers to the fact that the amount of energy we can observe in the universe does not match the amount predicted by our current understanding of physics. Cosmological redshift plays a role in this because it affects our measurements of the energy emitted by distant objects, making it difficult to accurately calculate the total energy of the universe.</p><h2>3. How much energy has gone missing due to cosmological redshift?</h2><p>It is difficult to determine exactly how much energy has gone missing due to cosmological redshift, as it depends on the distance and age of the objects being observed. However, it is estimated that around 95% of the total energy in the universe is currently unaccounted for.</p><h2>4. Does cosmological redshift affect all types of light?</h2><p>Yes, cosmological redshift affects all types of light, including visible light, infrared light, and ultraviolet light. However, the amount of redshift varies depending on the wavelength of the light, with longer wavelengths experiencing more redshift than shorter wavelengths.</p><h2>5. Can cosmological redshift be used to measure the expansion of the universe?</h2><p>Yes, cosmological redshift is a key tool in measuring the expansion of the universe. By studying the redshift of light from distant galaxies, scientists can determine the rate at which the universe is expanding, which provides important insights into the history and future of our universe.</p>

1. What is cosmological redshift?

Cosmological redshift is the phenomenon where light from distant objects in the universe appears to be shifted towards the red end of the electromagnetic spectrum. This is due to the expansion of the universe, which stretches the wavelengths of light as it travels through space.

2. How is cosmological redshift related to the missing energy in the universe?

The missing energy in the universe refers to the fact that the amount of energy we can observe in the universe does not match the amount predicted by our current understanding of physics. Cosmological redshift plays a role in this because it affects our measurements of the energy emitted by distant objects, making it difficult to accurately calculate the total energy of the universe.

3. How much energy has gone missing due to cosmological redshift?

It is difficult to determine exactly how much energy has gone missing due to cosmological redshift, as it depends on the distance and age of the objects being observed. However, it is estimated that around 95% of the total energy in the universe is currently unaccounted for.

4. Does cosmological redshift affect all types of light?

Yes, cosmological redshift affects all types of light, including visible light, infrared light, and ultraviolet light. However, the amount of redshift varies depending on the wavelength of the light, with longer wavelengths experiencing more redshift than shorter wavelengths.

5. Can cosmological redshift be used to measure the expansion of the universe?

Yes, cosmological redshift is a key tool in measuring the expansion of the universe. By studying the redshift of light from distant galaxies, scientists can determine the rate at which the universe is expanding, which provides important insights into the history and future of our universe.

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