Arp is obviously a bright guy (Harvard educated) and has vast experience in his field (Hubble's assistant/Palomar astronomer), so he can't be dismissed as a quack. It would certainly be... well, earth-shattering if he turned out to be right. I haven't figured it out yet.

I'm still trying to get my brain wrapped around the dark matter concept. I just can't escape the nagging suspicion that there is something about the weak force that isn't properly understood that would negate the need for invisable and inert matter that only produces gravitons in this dimension.

"Does that seem right to you?" - Jubal Early

I read Arp's "Seeing Red" - and while it isn't the best written or even organized book, there's lots of logic in there. I am not an astrophysicist, by any stretch, but what he's saying makes sense - if you see these quasar like entities always in pairs, and always on either side of a galaxy that isn't highly red-shifted, well, that might just maybe mean something - and given the way we've put our knowledge together, something big.

It seems to me that we are ripe for a paradigm shift. Dark matter looks like fudging to me. Arp's theories could be a way around that. And the fact that our current cosmology has predictive capabilities is no guarantee of "correctness" - you could predict eclipses with Ptolemy's super-complicated theory, but it was still wrong.