"The ordinary adult never gives a thought to space-time problems.... I, on the contrary, developed so slowly that I did not begin to wonder about space and time until I was an adult. I then delved ...

"The ordinary adult never gives a thought to space-time problems ... I, on the contrary, developed so slowly that I did not begin to wonder about space and time until I was an adult. I then delved ...

One of Albert Einstein's greatest insights was realizing that time is relative. It speeds up or slows down depending on how fast one thing is moving relative to something else. How much does it ...