What Is Relativity?: An Intuitive Introduction to Einstein’s Ideas, and Why They Matter

A black hole is an object so massive that even light cannot escape its gravitational pull. What would happen if your friend jumped into one? From his perspective, he would quickly accelerate until he was crushed. But from your perspective, as he got closer, his descent would slow, until it finally stopped (at the “event horizon”). According to Bennett’s explanation, he would never fall any further. If you decided to visit a black hole twenty-five light years away, and traveled at a speed 99% of the speed of light, how long would it take you? About 25 years? Think again. In fact, as Bennett explains, it would take somewhere around three years, from your perspective, though the 25 years would have passed for everyone that you left behind on earth.

In this clear text, these, and many other surprising conclusions, are derived through simple logic from just a couple of intuitive and understandable laws of nature. From here, with very little math, and in an extremely accessible way, the author uncovers the mystery of relativity and converts it into common sense.