Is our universe haunted? It might look that way on this
dark matter map. The gravity of unseen
dark matter is the leading explanation for why
galaxies rotate so fast, why
galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and how
visible matter is distributed. The featured image from the
American Museum of Natural History's
Hayden Planetarium Space Show, Dark Universe, highlights one example of how pervasive dark matter might haunt our universe. In this frame from a
detailed computer simulation, complex filaments of dark matter, shown in black, are strewn
about the universe like
spider webs, while the relatively rare clumps of familiar
baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a
scarier turn of events,
dark matter -- although quite strange and in an
unknown form -- is no longer thought to be the strangest source of
gravity in the universe. That honor now falls to
dark energy, a more uniform source of
repulsive gravity that seems to now dominate the
expansion of the entire
universe.