A brief history of dark matter

Summary

Introduction

The title not withstanding, this is not a history of dark matter. Until we know what the dark matter is, we cannot know its history. Instead, this is a brief history of how astronomers converged to the view that most of the matter in the universe is dark. This paper deals principally with the early studies which helped to answer the questions “Are rotation curves flat? If so, why?” It also includes some early history in deciphering the signature of clusters of galaxies as gravitational lenses, which seems to have been little investigated. This account covers the years up to 1980; achievements since 1980 are science, not history. Several excellent, informative brief histories exist, and interested readers should see Trimble (1987, 1995) and van den Bergh (1999). We can all thank Sidney van den Bergh for correctly translating Zwicky's “dunkle (kalte) materie” as “dark (cold) matter” and finally putting to rest the myth that Zwicky called it “missing matter.”

The notion that there are stars that are dark was a common one in the 18th and 19th Century. Walt Whitman's (1855) lines in Leaves of Grass, “The bright suns I see and the dark suns I cannot see are in their place” and Bessel's “Foundation of an Astronomy of the Invisible” (Clerke 1885 and reference therein) are early manifestations of this belief.