Andromeda, Galactic Redshift, and the Big Bang Theory

Abstract

Edwin Hubble’s establishment of the Andromeda Nebula as a distinct galaxy demolished one vision of the universe that had existed in the West since the ancient times. His use of Cepheid variables in M31 to determine the distance to this Messier object not only provided definitive proof and support for the island-universe theory but it also forced astronomers to enlarge their estimates of the size of the universe by many times. If the Andromeda Galaxy, according to Hubble, was nearly 1,000,000 light-years distant, the universe was infinitely larger than any had previously thought. But was it truly infinite, or were there some bounded limits to its size? Moreover, what was the shape of the universe, and could one speak of it having a center? These were but a few of the questions that remained as the 1920s closed and the last remnants of the single-galaxy universe theory were abandoned and replaced by one defined by an island-universe view.