The Structure of the Universe

Abstract

Edwin Hubble (1889–1953) was born in Marshfield, Missouri. He received his Bachelor of Science degree from the University of Chicago in 1910, where he concentrated on astronomy, mathematics and philosophy. As a Rhodes scholar at The Queens College, Oxford, he studied jurisprudence, literature and Spanish. He returned to his interest in astronomy after serving as a high-school teacher for a few years, earning his doctorate from the University of Chicago in 1917. There, he carried out photographic studies of faint nebulae at the Yerkes observatory in Williams Bay, Wisconsin—home to the largest refracting telescope in the world (see Fig. 26.1). After serving in the United States Army in World War I, he went to work at the Mount Wilson Observatory, where he studied Cepheid variables in spiral nebulae. Building upon the work of Henrietta Leavitt, Ejnar Hertzsprung, Vesto Slipher and Harlow Shapley, he was able to establish a relationship between the recessional velocities of galaxies and their distances from the earth—what is now known as Hubble’s Law. The Hubble Space Telescope, named after the famous cosmologist, was launched into low-earth orbit in 1990 and has subsequently produced thousands of popular and beautiful images of galaxies and other astronomical objects. In the following reading selection, which appeared in The Scientific Monthly in 1934, Hubble begins by describing how nebulae appear when viewed through powerful telescopes, and also how their distribution throughout the observable regions of the universe is calculated. After this he proceeds to explain his famous velocity–distance relationship. As you study this text, try to identify any assumptions made by Hubble. Are his reasonable assumptions? Is there a better approach?

On this interpretation the nebulae are rushing away from us, and the farther away they are, the faster they are traveling.

—Edwin Hubble