Space — the final frontier. These are the words that introduce every episode of classic "Star Trek," the show that essentially popularized the concept of traveling the stars at the speed of light – or ...

The speed of light is a fundamental constant, approximately 299,792,458 meters per second. It's the same for all observers and hasn't changed measurably over billions of years. Nothing can travel ...

Every generation grows up with starships that jump across galaxies in a heartbeat, but the real universe is far less forgiving than the screen. The same physics that lets GPS satellites work and ...