Cosmologists debate how old the universe is, and most current estimates place the figure at 10 billion to 15 billion years. Determining the age of the universe is a subject of fascination to astronomers because the chief clue to cosmic age--the expansion rate of the universe --is integral to theories about the Big Bang and other topics.
The really interesting question, though, may not be how long the universe has already existed, but rather, how much longer will it exist. A few decades ago, cosmologists tended to assume that because the firmament is billions of years old and looks "mature," in the sense of having lots of well-formed stars and other structures, the cosmos must already be old and winding down. It was assumed, for example, that no more new stars could possibly be forming.
Instead it turns out that new stars are forming almost everywhere astronomers look. Other indicators suggest that by its own standards, the cosmic enterprise is just getting under way. Alan Dressler, an astronomer at the Carnegie Observatories, recently estimated that the universe will last for at least thousands of billions of years -- a figure that for intents and purposes might as well be eternity. Humanity may have acquired its being not when the universe was old and running down, but close to the beginning of a cosmic enterprise of majestic scope and span.