Arp was also known as a critic of the Big Bang theory and for advocating a non-standard cosmology incorporating intrinsic redshift.

Arp became a research assistant at Indiana University in 1955, and then in 1957 became a staff member at Palomar Observatory, where he worked for 29 years.

Astronomers now recognize Arp's atlas as an excellent compilation of interacting and merging galaxies, with some admixture of chance alignments of two unrelated objects at vastly different distances.

When the spectrum of the star was measured, it contained unidentifiable spectral lines that defied all attempts at explanation; John Gatenby Bolton's suggestion that these were highly redshifted sources was not widely accepted.

In some photographs a quasar is in the foreground of known galaxies, and in others there appeared to be matter bridging the two objects, implying they are very close in space.

Arp also noted that quasars were not evenly spread over the sky, but tended to be more commonly found in positions of small angular separation from certain galaxies.

Nearby galaxies with both strong radio emission and peculiar morphologies, particularly M87 and Centaurus A, appeared to support Arp's hypothesis.

[16] He explained his reasons for believing that the Big Bang theory is wrong, citing his research into quasars or quasi-stellar objects (QSOs).

[17] As more recent experiments have expanded the amount of collected data by orders of magnitude Arp's theories can now be scrutinized further.

The authors argue that In a 2009 paper Bell and Comeau retracted the claim that these features were due to redshift periodicity, and acknowledged that they are caused by subtle selection biases.

[20] The SDSS team had previously described these effects, and shown that the apparent peaks in the redshift distribution disappear when restricted to a highly-complete subsample of quasars.