For reasons of economy, all that was actually simulated was the invisible dark matter, currently believed to make up as much as 90 percent of creation.

He concentrated on the invisible matter that was close before him-and he struck home.

That cannibalism provides an important clue to the extent and nature, if not the identity, of the mysterious invisible matter that dominates the universe.

About 90 percent of the mass of the universe is believed to be composed of invisible matter.

"We knew a large amount of invisible matter was out there, because of the gravitational effects, but we didn't know it was alive."

Do you know of invisible matter?

Some observations have showed the presence of considerable amounts of invisible matter in ordinary form at the edge of the Milky Way and other galaxies.

Shrouds of the Night is an astronomy book written to teach the average public about dark matter, the invisible matter which comprises about 70% of space.

But in the last year or so scientists have found structures so large that they can't be accounted for even by conjuring up invisible matter.

At the time, most scientists contended that, rather than a vacuum, some invisible matter was present.