What Are the Implications of Relativistic Redshift on Our Understanding of Time?

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Discussion Overview

The discussion centers on the implications of relativistic redshift for our understanding of time and the expansion of the universe. Participants explore the relationship between redshift, velocity, and the expansion of space, as well as the interpretations of cosmological observations.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation

Main Points Raised

  • Some participants propose that redshifts in special relativity arise directly from velocities, leading to interpretations of the universe's expansion based on Hubble's observations.
  • Others argue that the velocity associated with redshift is due to the rate of expansion of space rather than movement through space, suggesting that special relativistic Doppler shift formulas may not apply at high redshift.
  • One participant questions what experiments or observations have ruled out the possibility of objects moving through space, indicating a need for clarity on this point.
  • Another participant mentions that the tight and linear relationship between distance and redshift does not rule out the possibility of movement through space, but rather introduces new possibilities.
  • Some participants acknowledge that while part of the observed redshifts may be due to motion through space, the overall interpretation of redshift remains complex and multifaceted.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of redshift and its implications for movement through space. There is no consensus on whether observations definitively rule out the possibility of motion through space contributing to redshift.

Contextual Notes

Participants highlight the complexity of the relationship between redshift and cosmic observations, noting that various models may fit the data differently. There are unresolved questions regarding the assumptions underlying these interpretations.

ranyart
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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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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.
 
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?
 
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.
 
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!
 
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.
 

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