In the 1900s, Albert Einstein unified the concepts of space and time, giving us a useful new way to picture the universe. At the start of the 20th century, physicists had a problem: The speed of light ...

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 ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...