For millennia, our ancestors speculated about whether the universe has existed forever or whether it began some finite time in the past. Did God create the universe, or was its creation an event that required no divine intervention? Science has yet to provide an answer to this question. But astronomers and other scientists have determined that it began at a finite time in the past and they have accumulated a great deal of knowledge about what has happened to the universe starting a tiny fraction of a second after it began, and what its fate will be. Although the overall theory of cosmic evolution is not complete, its major elements are consistent with observations.

In this chapter we will examine the distribution of matter on the largest scales in the universe and how this matter is moving and changing. Using this information, we will explore the Big Bang model of how the universe has evolved from its earliest moments, when it was smaller than an atom. We will see how it grew and created matter as we know it, forming and evolving large-scale systems, like galaxies and groupings of galaxies. Finally, we will consider the fate of the universe.