Another nail in the coffin of alternative redshift theories

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    Redshift Theories
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Discussion Overview

The discussion revolves around the topic of cosmological redshift and its implications for understanding cosmic expansion. Participants explore a specific paper titled "Direct Determination of Expansion History Using Redshift Distortions" and its relevance to alternative theories regarding redshift and expansion history.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants express skepticism about the understanding of cosmological redshift and its treatment in the literature, referring to it as often targeted by "crackpot physics zealots."
  • One participant questions the meaning of "CAMB output" and "floating measures," seeking clarification on these terms.
  • Another participant explains that CAMB refers to a computer code for modeling cosmological parameters, while floating measures are used to plot parameters without fitting data to a specific cosmological model.
  • A participant suggests that floating measures might relate to input values with variances to assess uncertainty, prompting further clarification from others.
  • There is a discussion about the paper's focus on measuring expansion history through galaxy density and whether it adequately addresses sample selection and population evolution.
  • Some participants agree that the article attempts to quantify expansion history while minimizing the influence of prior assumptions.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the discussed paper, with some agreeing on its focus on expansion history while others question its relevance to cosmological expansion. There is no consensus on the interpretation of floating measures or the paper's coverage of certain topics.

Contextual Notes

Participants note the complexity of the terms and concepts discussed, indicating that some assumptions and definitions may not be fully understood or agreed upon.

Chronos
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Cosmological redshift is often targeted by crackpot physics zealots. Here is a sober discussion worthy of review: Direct Determination of Expansion History Using Redshift Distortions, http://arxiv.org/abs/1210.6596
 
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I can't say I understand it, but I'm glad someone wrote it lol.
 
Chronos, I don't pretend to understand the content, but could I ask:
1. "CAMB output" is mentioned (page 5) but I'm not familliar with this group / experiment. What is CAMB (or what does it stand for)?
2. There are a number of references to "floating measures", but again I am not familliar with this phrase. What does it mean?Regards,

Noel.
 
CAMP, Code for Anisotropies in the Microwave Background, is a computer code for modeling cosmological parameters and handy for things like power spectrum analyses and lensing surveys. It is maintained by various institutions, including NASA. Floating measures are used to plot parameters like distance and power spectra without tweaking the data to fit any particular cosmological model.
 
Thanks Chronos. In relation to floating measures, does it equate to an input value +/- a variance to check / confirm the impact of uncertainity?

Regards,

Noel.
 
That's not the purpose of floating measures, Lino. The variance between fitted and floating measures is the what the author is trying to quantify.
 
Chronos said:
Cosmological redshift is often targeted by crackpot physics zealots.
I believe it's cosmological expansion not cosmological redshift that is often targeted by crackpots.

Chronos said:
Here is a sober discussion worthy of review: Direct Determination of Expansion History Using Redshift Distortions, http://arxiv.org/abs/1210.6596
As I see this article has little to do with your implication that it tests cosmological expansion. Nonetheless it is rather interesting as it tries to give alternative method how to get parameters for accelerated expansion.

If I understand it correctly it proposes to measure expansion history (acceleration history) by means of galaxy density. Do you see it the same way?

Did it cover sample selection and population evolution (galactic mergers) questions? I didn't noticed. But then I didn't read it all.
 
I believe you are correct, it is an effort to quantify expansion history and attempts to minimize the influence of 'a priori' assumptions.
 
Chronos said:
That's not the purpose of floating measures, Lino. The variance between fitted and floating measures is the what the author is trying to quantify.

Thanks Chronos.

Regards,

Noel.
 

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