WASHINGTON — Using data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), scientists have identified an unexpected motion in distant galaxy clusters. The cause, they suggest, is the ...

Thomas Mulligan explains that the observable universe is limited by the particle horizon, a boundary beyond which we cannot ...

The universe may be far bigger than we can ever see. This video explains why the observable universe stretches far beyond its age. Explore the theories that challenge our understanding of space, time, ...