PHILADELPHIA - As if it weren't strange enough that the cosmos is loaded with invisible and elusive matter, a new theory has the stuff wandering through the early universe like a drunken sailor.

The idea is a serious attempt to examine dark matter -- which is far more prevalent than normal matter -- by modeling its behavior, despite the troubling fact that no one knows what it actually is. The result is an animation showing how thousands of relatively small and invisible dark matter galaxies might have developed and still reside in the vicinity of our own Milky Way.

Chung-Pei Ma, an astronomer at the University of California, Berkeley, unveiled the new theory here last week at a meeting of the American Physical Society. Ma envisions dark matter particles behaving like bits of dust bounced around by water molecules in a microscopic process called Brownian motion.

Ma describes Brownian motion as being something like the unpredictable path of a drunken sailor. She and her colleague, Ed Bertschinger of MIT, were surprised that the basic principle of Brownian motion could be applied on a galactic scale, but the results fit a line of theoretical thinking that predicts dark satellite galaxies should exist.

Scientist suspect the bulk of dark matter involves tiny particles they've yet to detect. The two leading candidates are called axions and neutralinos. Whatever they are, they are known to interact gravitationally with regular matter, because observable matter can't account for the speed with which stars move around galactic centers.

Dark matter particles appear not to interact with electromagnetic forces, however. They don't make or reflect light, which explains why they can't be seen.

"It has to be some kind of exotic particle, something we can't touch," Ma said.

Dark matter satellite galaxies -- if they exist -- cannot be detected by conventional telescopes because they don't contain enough normal matter to fuel star birth.

But thousands of dark galaxies develop in the simulation, too, each containing masses equal to several million suns.

"We then realized that the motion of dark matter can also be described statistically by a similar equation used for the Brownian motion," Ma told SPACE.com. "This equation is very different from Newton's law [of gravity] used in the computer model. This doesn't mean Newton's law is not applicable -- it means the new equation that we found provides a new language for describing how dark matter clumps."

A paper describing the new work will soon be submitted to the Astrophysical Journal for possible publication.

If dark satellite galaxies exist, astronomers should be able to detect some of them. Their gravity would bend light traveling toward Earth from more distant objects, distorting and possibly magnifying them. This so-called gravitational lensing effect is used already to study distant objects by peering through and around visible, intervening galaxies or galaxy clusters.

Finding and cataloguing these dark matter galaxies would help researchers understand what they're made of.

"Different dark matter models [for material that is cold or warm] predict different number of these dark galaxies," Ma said. "So if we can estimate the number and masses of these galaxies, it can constrain the nature of dark matter."

Saul Perlmutter of the Lawrence Berkeley National Laboratory, speaking at the same meeting of physicists, said knowledge of dark matter has come a long way since the first strong hints of it emerged in the 1970s. Researchers no longer wrestle with whether it exists or how much there is but instead can focus on its properties, Perlmutter said.

He added, though, that physicists should remain humble about the time it might take to figure out the remaining mysteries.