Dark matter�s hideout just got smaller, thanks to supercomputers.

Lattice QCD. Artist�s impression.

Physicists know they are missing something. Evidence that something�s wrong has piled up for decades: Galaxies and galaxy clusters don�t behave like Einstein�s theory of general relativity predicts. The observed discrepancies can be explained either by modifying general relativity, or by the gravitational pull of some, so-far unknown type of �dark matter.�