Time for Change: Exploring Relativistic Redshift Effects

In summary: Originally posted by ranyart The observation that the relationship between distance and redshift is tight and 'linear'; if the redshifts were due to movement through space, the Milky Way/Local Group would be the true centre of the universe.
  • #1
ranyart
370
0
About Time!

This paper has such a obvious ring of truth about it, one can only hope that the misconceptions are finally laid to rest, and we can move forward, for there is Relativistic change in the air.

http://uk.arxiv.org/abs/astro-ph/0310808

Here is an interesting paragraph:In special relativity, redshifts arise directly from velocities. It was this idea that led
Hubble in 1929 to convert the redshifts of the “nebulae” he observed into velocities,and predict the expansion of the universe with the linear velocity-distance law that now bears his name. The general relativistic interpretation of the expansion interprets
cosmological redshifts as an indication of velocity since the proper distance between comoving objects increases. However, the velocity is due to the rate of expansion of space, not movement through space, and therefore cannot be calculated with the special relativistic Doppler shift formula. Hubble & Humason’s calculation of velocity
therefore should not be given special relativistic corrections at high redshift, contrary to their suggestion.

There is a simple thought experiment that can break a number of chains, I have been waiting for the right paper to surface with just the right amount of clarity so I can put the experiment into a perspective frame. I will dig out from my annuls of paperwork, and place it here for inspection.
 
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  • #2


Originally posted by ranyart
The general relativistic interpretation of the expansion interprets
cosmological redshifts as an indication of velocity since the proper distance between comoving objects increases. However, the velocity is due to the rate of expansion of space, not movement through space, and therefore cannot be calculated with the special relativistic Doppler shift formula.
Doppler shift works the same regardless of how you define the motion. If you are standing on the platform and the train is moving past you or the train is sitting still and you drive past it in a car, the doppler shift of the horn sounds the same.

The reason the galaxies are moving apart is not important to redshift. The fact that galaxies are moving apart is.
 
  • #3
However, the velocity is due to the rate of expansion of space, not movement through space

I'm curious as to what experiment or observation ruled out the possibility. - That of moving through space?
 
  • #4


Originally posted by russ_watters
The reason the galaxies are moving apart is not important to redshift.

That's not really correct. You cannot use the special relativistic formula for velocity Doppler shift to calculate redshifts in an expanding space. So, for instance, you cannot account for the Hubble redshifting of distant galaxies by postulating recessional motion in a flat spacetime. That's the point of the cited paper.
 
  • #5
Originally posted by Arc_Central
I'm curious as to what experiment or observation ruled out the possibility. - That of moving through space?

Ok I'll put the thought experiment up for grabs here, I do not want to make it longer than is needed, without compromising the bigger picture, I am in the middle of digging out the paperwork in my house-front living room, so Ill be back shortly.
 
  • #6
Originally posted by Arc_Central
I'm curious as to what experiment or observation ruled out the possibility. - That of moving through space?
The observation that the relationship between distance and redshift is tight and 'linear'; if the redshifts were due to movement through space, the Milky Way/Local Group would be the true centre of the universe.

The cosmic microwave background is interpreted to be the highly redshifted black-body radiation from the era of decoupling of matter and radiation (protons captured electrons to form H atoms).

Plug all the observations - these and many others - into your a thousand models of the universe and see which best match the data.

Of course, some part of the observed redshifts of galaxies is due to motion through space; the richer the cluster, the greater the 'velocity' dispersion about the cluster mean, and there are some quite monsterous clusters!
 
  • #7
The observation that the relationship between distance and redshift is tight and 'linear'; if the redshifts were due to movement through space, the Milky Way/Local Group would be the true centre of the universe.

The cosmic microwave background is interpreted to be the highly redshifted black-body radiation from the era of decoupling of matter and radiation (protons captured electrons to form H atoms).

Niether of these observations rules out the possibility. They just add new possibilities. Although these are somewhat compelling - I'm looking for the knockout punch. What observation or experiment makes it impossible that objects are moving through space at a higher rate the further out you look? Surely there must be something, because nobody of standing in cosmology and whatnot considers it to be even a remote possibility.
 
  • #8
Originally posted by Arc_Central
Niether of these observations rules out the possibility.

Yes, they do. Cosmological redshift expanding space predicts a different redshift-luminosity (or redshift-distance) relation than does Doppler reshift from recession a non-expanding space. See, for instance, exercise 29.5 of Misner et al.

Anyway, if you're so curious about this issue, why don't you read the paper that started this thread?? They've got calculations, data, and everything.
 

1. What is the concept of "relativistic redshift"?

Relativistic redshift is a phenomenon in which light emitted from an object that is moving away from an observer appears to have a longer wavelength, or "redshifted". This is due to the effects of relativity, specifically the time dilation and length contraction of the object's motion.

2. How does the speed of light affect relativistic redshift?

The speed of light plays a crucial role in relativistic redshift because it is the universal speed limit in the universe. As an object moves away from an observer at high speeds, the light waves it emits are stretched out, resulting in a longer wavelength and a redshifted appearance.

3. What are some examples of objects that demonstrate relativistic redshift?

Some common examples of objects that exhibit relativistic redshift are galaxies, quasars, and other celestial bodies moving away from the observer at high speeds. This effect can also be observed in laboratory experiments with high-speed particles.

4. How does the distance between an observer and an object affect relativistic redshift?

The distance between an observer and an object does not directly affect relativistic redshift. However, the distance can indirectly affect the observed redshift by influencing the object's velocity and the resulting time dilation and length contraction effects.

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

Yes, relativistic redshift is one of the key pieces of evidence used to support the theory of the expanding universe. By measuring the redshift of light from distant galaxies, scientists can determine the rate at which the universe is expanding.

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