Where is it going? How is it put together? How did it get to be the way it is? These are Big Questions. Like others of their ilk, they are easy to ask and very hard to answer. Humans seek answers for deep philosophical reasons—reasons that have very little to do with the immediate applications of technology. No one is going to get rich from discovering the structure of the universe (unless, of course, she decides to write a book about it). The branch of science devoted to these Big Questions is called cosmology. Modern thought in this area derives from the fact that: The universe was born at a specifictime in the past, and it has beenexpanding ever since. THE EXPANSION OF THE UNIVERSE Edwin Hubble established the existence of other galaxies, but this was not the most important result of his work. When he looked at the light coming from those galaxies, he found that it was shifted toward the red. That is, its wavelength was longer than that of the light emitted from corresponding atoms in laboratories.
