universe

The universe began 13.8 billion years ago and will end — eventually. But how? Heat death, the Big Rip, the Big Crunch, and vacuum decay are all on the table. Here's what physics actually predicts for the final fate of everything.

Nothing with mass can reach the speed of light. But shadows, spots of light, and the expansion of the universe can move faster than light without violating physics. Here's the strange truth about superluminal motion.

The observable universe is 93 billion light-years across. The full universe is bigger — possibly infinitely so. Here's what we can measure, what we can't, and why.