A critical mass is the minimum amount of material (fissile, if you want to be technical) needed to maintain a nuclear chain reaction. Without enough fissile material, nuclear energy cannot be produced.In the cycling world, a critical mass is an event...

Critical Mass plans to hit Lincoln Highway Friday to bring awareness to bicyclists. "Critical Mass is a group of cyclists biking together to bring awareness to the bikers in DeKalb," said Critical Mass coordinator Dave Anianas Jr. Accidents involving...