The Dark Truth
Photograph by John Dubinski, University of Toronto
No one can see it, or feel it, or even know what it is. But without the mysterious substance called dark matter, galaxies would fly apart. A computer simulation by John Dubinski, an astrophysicist at the University of Toronto, pictures dark matter as an enormous web of filament stretching through space, shown in white above. According to calculations by Dubinski and other astrophysicists, the visible universestars and galaxiesis a mere sliver of what is out there. Dark matter is believed to account for at least 90 percent of all matter. The best guess is that dark matter is a large particle with no electrical charge; its only signature is its gravitational pull. Experts predict that within the next ten years experiments will finally isolate dark matter particles and unmask the universe's biggest mystery.