Redshift Anomaly: Progress & Confusion

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Discussion Overview

The discussion centers around the redshift anomaly observed in certain galaxies, particularly those noted by Halton Arp, and the implications of these observations for our understanding of cosmic interactions and redshift interpretations. Participants explore the nature of these anomalies, the standard explanations, and the criteria for evaluating the validity of the claims regarding physical connections between galaxies.

Discussion Character

  • Debate/contested
  • Exploratory
  • Conceptual clarification

Main Points Raised

  • Some participants highlight Halton Arp's observations of galaxies that appear to be physically interacting through gas filaments, despite having significantly different redshifts.
  • Others present the standard view that these observations can be explained as chance alignments of near and far objects, suggesting that the physical connections do not exist.
  • One participant expresses uncertainty about whether the standard explanation is sufficient to account for the observations.
  • A later reply questions what criteria would be necessary to convince someone of the validity of the Arp hypothesis, noting that the Arp idea posits that no intermediate redshift material exists between the galaxies.
  • Another participant mentions that as new observations are made in different wavebands and at higher resolutions, fewer examples of 'real Arpian interactions' seem to persist, yet new examples continue to emerge.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the interpretation of the redshift anomaly and the validity of the standard explanation versus the Arp hypothesis. No consensus is reached on the sufficiency of the explanations provided.

Contextual Notes

The discussion reflects varying assumptions about the nature of redshift and the criteria for evaluating physical interactions between galaxies. Limitations in observational data and definitions of redshift are acknowledged but not resolved.

paul_peciak
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Has there been any progress in clarifying this anomaly? I am a bit confused as to how people can ignore this problem?
 
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paul_peciak said:
Has there been any progress in clarifying this anomaly? I am a bit confused as to how people can ignore this problem?

What anomaly?
 
Halton Arp observed galaxies that seem to be interacting physically with other galaxies through gas filaments yet the redshift between the two are radically different.
 
paul_peciak said:
Halton Arp observed galaxies that seem to be interacting physically with other galaxies through gas filaments yet the redshift between the two are radically different.

The standard view is that these are chance alignments between near and far objects, and that the physical connections don't really exist.
 
I realize that, I'm just on the fence weather that is a good enough answer...
 
It's an interesting question - what would constitute a sufficiently strong case to get you off the fence?

Here's one aspect: AFAIK, the Arp idea requires that 'not one atom' of material have a redshift intermediate between the redshifts of the two galaxies (so any search for intermediate redshift material - somewhere in a bridge, for example - is doomed to failure). Yet, in the Arp idea, all atoms behave just like the atoms here on Earth, in terms of their 'lab transition wavelengths', their motion in magnetic fields, their response to gravity, and so on.

Here's another aspect: the more closely these examples of so-called physical interaction are looked at - in new wavebands, at higher resolutions, etc - the fewer 'real Arpian interactions' seem to remain. Yet somehow new examples always get added - fainter systems, smaller (angular size) systems, etc.
 

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