The contribution of VM Slipher to the discovery of the expanding universe

Abstract

A brief history of the discovery of the expanding universe is presented, with an emphasis on the seminal contribution of VM Slipher. It is suggested that the well-known Hubble graph of 1929 could also be known as the Hubble-Slipher graph. It is also argued that the discovery of the expanding universe matches the traditional view of scientific advance as a gradual process of discovery and acceptance, and does not concur with the Kuhnian view of science progressing via abrupt paradigm shifts.