Cosmology is the study of the structure and evolution of the Universe as a whole. Cosmologists seek answers to questions such as, How big is the Universe? What shape is it? How old is it? How did it form? What will happen to it in the future?

Given our insignificant size in the cosmos, such questions may seem futile or even arrogant, but most cultures have tried to answer them. Many of those attempted answers have become part of humanity's religious heritage. For example, the Bible, in the book of Genesis (1:1-3), states that:

In the beginning God created the heaven and the earth; and the earth was without form and void; and darkness was upon the face of the deep and the spirit of God moved upon the face of the waters. And God said, "Let there be light," and there was light. And God saw the light, that it was good.

These simple but powerful words, rich in symbols, give one picture of the birth of the Universe. But despite their power, they offer few specifics of what our Universe was like at its birth. In this final chapter, we will learn how contemporary scientists view the creation and evolution of our Universe, beginning with the observational discoveries that the Universe is expanding and that it is filled with a very low-energy background radiation. This expansion and radiation imply that the Universe was born about 15 billion years ago in a hot, dense, violent burst of matter and energy called the Big Bang. Within the last few decades, cosmologists have sought to extend our knowledge of the Universe to before the Big Bang and have discovered that the Universe may have been born in even more turbulent events known as the inflationary stage, a time when the entire Universe that we see today may have fit in a volume smaller than a proton.