No one knows if the universe is infinitely large, or even if ours is the only universe there is.

Although our view of the universe is limited, our imaginations are not. Astronomers have indirect evidence that the universe of galaxies extends far beyond the region we can see. But no one knows if the whole universe is infinitely large - large beyond limit.

According to the leading theories, other parts of the universe may look very different from our own - and may even have different laws of nature. We may never be able to find out for sure. But it is possible that clues to the answer lie in plain view, just waiting to be discovered!

The Future. NASA's LISA mission will look for ripples in the fabric of space, predicted by Albert Einstein. Such clues may help refine theories about what the rest of the universe is like.

ABOVE: New telescopes on Earth and in space will continue to expand our view of this magnificent universe.