A disagreement between observations of galaxy clusters and the cosmic background radiation could be explained by the existence of a fourth type of neutrino.
At SLAC National Accelerator Laboratory, researchers are using a particle accelerator to help them search for the source of ultra-high-energy cosmic rays.
Theoretical physicist David Kaplan discusses his new documentary “Particle Fever,” which followed scientists around the world for seven years as they hunted for the Higgs boson.