Introduction

Extract

As we approach the 21st Century, enormous technical advances are being made in the acquisition of galaxy redshifts. This Joint Discussion offers a perspective on those advances and the associated redshift surveys. It is representative, but by no means all inclusive.

My introduction offers some historical background, against which the new methods and achievements can be measured.

Redshift surveys tells us about the spatial distribution and evolution of galaxies. Yet the study of large-scale structures in the distribution of galaxies goes back further than one might imagine. The first accurate description of the Virgo Supercluster was given by John Herschel in the mid-19thCentury. To paraphrase Sir John, “Virgo is the central condensation of a roughly spherical cluster of nebulae - our system lies outside the denser part of the cluster, but is involved with its outlying members - forming an element of some one of its protuberances or branches”.

Victorian science might have beaten Hubble had more people believed John Herschel - and had he himself more confidence in his interpretation. Few were prepared to accept the ‘Island Universe’ theory that it implied, and strong criticism followed. Moreover, Herschel was very reluctant to go against the beliefs of his revered father, William Herschel, who, though once believing in the ‘Island Universes’, had in later life accepted that all nebulae were somehow gaseous condensations in our system. Consequently, even John Herschel’s textbook still stated the older, incorrect interpretation.