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Some scientists believe that the universe may be a large number, perhaps an infinite number - Other closure of a well-off universe theory. Some may grow, and then collapse, life and death, in an instant. Other possible to expand forever. Some people may also be subtle, and a large number, perhaps an infinite number - the expansion and contraction. Our own universe is about billions past its origin, or at least is the current embodiment of the Big Bang.           The Story and the Setting of Our Universe     Every culture has its creation myth—an attempt to understand where the Universe came from, and all within it. Almost always these myths are little more than stories made up by story tellers. In our time, we have a creation myth also. But it is based on hard scientific evidence. It goes something like this...   We live in an expanding Universe, vast and ancient beyond ordinary human understanding. The galaxies it contains are rushing away from one another, the remnants of an immense explosion, the Big Bang. Some scientists think the Universe may be one of a vast number—perhaps an infinite number—of other closed-off universes. Some may grow and then collapse, live and die, in an instant. Others may expand forever. Some may be poised delicately and undergo a large number—perhaps an infinite number—of expansions and contractions. Our own Universe is about 15 billion years past its origin, or at least its present incarnation, the Big Bang.   There may be different laws of Nature and different forms of matter in those other universes. In many of them life may be impossible, there being no suns and planets, or even no chemical elements more complicated than hydrogen and helium. Others may have an intricacy, diversity, and richness that dwarfs our own. If those other universes exist, we may never be able to plumb their secrets, much less visit them. But there is plenty to occupy us about our own.   Our Universe is composed of some hundred billion galaxies, one of which is the Milky Way. "Our Galaxy," we like to call it, although we certainly do not have possession of it. It is composed of gas and dust and about 400 billion suns. One of them, in an obscure spiral arm, is the Sun, the local star—as far as we can tell, drab, humdrum, ordinary. Accompanying the Sun in its 250 million year journey around the center of the Milky Way is a retinue of small worlds. Some are planets, some are moons, some asteroids, some comets. We humans are one of the 50 billion species that have grown up and evolved on a small planet, third from the Sun, that we call the Earth. We have sent spacecraft to examine seventy of the other worlds in our system, and to enter the atmospheres or land on the surfaces of four of them—the Moon, Venus, Mars, and Jupiter. We have been engaged in a mythic endeavor.         — Carl Sagan, Billions & Billions: Thoughts on Life and Death at the Brink of the Millennium, Chapter 5 – Four Cosmic Questions                       Indexes/16