Redshift Anomaly: Progress & Confusion

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The discussion centers on the redshift anomaly observed by Halton Arp, where galaxies appear to interact physically despite having significantly different redshifts. The standard explanation posits that these observations are mere chance alignments rather than genuine physical connections. Participants express confusion over the lack of attention to this anomaly, questioning the adequacy of the prevailing explanations. There is a debate about the implications of finding intermediate redshift material, which could challenge the current understanding. Overall, the conversation highlights ongoing uncertainty and the complexity of interpreting these astronomical observations.
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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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