Annu. Rev. Astron. Astrophys. 1991. 29: 499-541 Copyright © 1991 by Annual Reviews. All rights reserved

5.5 Controversies and Quantization

For many years, the conventional interpretation of the redshift in terms of the Hubble expansion has met with occasional skepticism. Since the time of the Bahcall-Arp debate on the redshift controversy in 1972 (Field et al 1973), some issues (e.g. energy requirements for quasars, infall into clusters) seem to have been resolved to the satisfaction of most. On the other hand, although the evidence is largely circumstantial, individual occurrences of alignments, apparent associations, and extreme velocities may not be easy to explain via the standard approach (e.g. Arp 1987).

Tifft and coworkers (see Tifft & Cocke 1989 and refs. therein) have claimed that quantization effects are present in a variety of redshift data bases, most notably in histograms of the radial velocity separation of members of binary systems. Evidence for this periodicity, mainly the manifestation of a 72.45 km s^-1 harmonic, has also been found, albeit not compellingly, in several different samples (Sharp 1984, Schneider et al 1986, Croasdale 1989). In examining the redshift distribution of different populations of objects in the Virgo cluster, Guthrie & Napier (1990) find no evidence for quantization in the redshift distribution of dwarf irregulars, but a possible periodicity (slightly different from Tifft's) appears in the power spectrum analysis of the brighter spirals. This effect is significant only with the further assumption that the Local Group is falling directly toward the Virgo cluster, as other solutions will not give results with the same significance.

On the skeptical side of the issue, Newman et al (1989) point out the statistical flaws of periodicity analysis in small-number samples, and Sharp (1990) further suggests that in the absence of statistically significant confirmation, the claimed periodicity is not a physical property of the galaxy pairs. In our opinion, redshift quantization is not yet rigorously proved. However, the verification of redshift quantization is potentially important because it does not fit within the framework of conventional dynamics.