While some of the smartest scientists in the world have been working for decades to pin down an age for the universe, it's still an elusive number and subject to hearty disagreement. The most commonly cited estimates are between 12 billion and 15 billion years.

Estimates come by finding distant sources of light (a star or galaxy 10 billion light-years away is 10 billion years old). But the estimates also depend on the rate at which the observable universe is expanding, which in turn is related to its exact composition and evolution.

All the confusion aside, Sweitzer, like any good scientist, has his own estimate of the age of the universe: "It's about 13 billion light-years from where we are to [the observable universe's] isotropic boundary, which is seen as the cosmic microwave background radiation."

As researchers push telescopic power to new limits, they have begun to see objects back to when the universe was just 2 billion years old or so. But they will likely never see the beginning.

"When we look in electromagnetic radiation (like light) we can only see the universe to the time when it was about 300,000 years old, because the universe was opaque to such radiation before that," Livio said.

So the universe is expanding, and it's been doing so for billions of years. And we can't see the beginning of it. All of which begs the next question.

"The observable universe is finite," Sweitzer said, which is to say that it had boundaries -- physical limits. Sort of. "It's a boundary to the events we can see directly, but not a boundary in the sense that New York State has a boundary."

And in an expanding universe, this boundary is constantly moving, as is everything within it. Cosmologists typically invoke a balloon with spots on its surface, representing galaxies, to explain the expanding universe. As the balloon is inflated, the spots grow farther apart. If you stood within one of these spots, you'd see all the others moving away from you, and the most distant spots would move appear to move the fastest.

Sweitzer goes on to say that the observable universe is probably part of a much larger universe, "which could be finite or infinite. Any global statements about the universe, such as overall extent, are speculative because they require extrapolating local mathematical theories and measurements beyond the observable universe."

So if the observable universe is finite, like the space occupied by a car or a house is finite, then there must be a brick wall or something up there, holding it all together. Right?

No, said Livio.

Argh. First you guys tell us the universe is expanding. Then you say it is finite. Now you say it has no edge! We need a visual here.

Livio is up to the task. He dredges up the old expanding balloon as his prop. "An ant traveling on the surface of a balloon will never reach an edge," Livio explains. "In the worst case it will return to its starting point."

And so too do we return. It is now a few moments later in the same year, 2001, heart of the same Information Age, well after the telescope was invented, and we still don't know how big the big house is nor what, if anything, lies beyond.

But now, perhaps we understand what we don't know a little better.