Astronomers have uncovered new clues about the nature of mysterious dark matter using NASA's Hubble telescope and the Chandra X-ray Observatory. The newest discovery is that dark matter doesn't decelerate when it collides against other dark matter. Previous theories held dark matter to be more interactive. If this new information is correct, it could eliminate some previous theories about the behavior of dark matter. For example: because dark matter doesn't slow down when it collides with itself, theories relying on strong friction are out the window.