What Is Relativity?: An Intuitive Introduction to Einstein's Ideas, and Why They Matter
*Starred Review* Doubtful in 1919 that even three scientists fully understood Einstein’s theory of relativity, the astrophysicist Arthur Eddington would marvel at this book. For in its relatively few pages, Bennett explains relativity to ordinary readers. Applying two simple principles—the uniformity of natural law and the invariance of the speed of light—readers conduct thought experiments that fuse time and space into a single concept. Armed with this concept, readers see why time slows down for space-travelers streaking across the cosmos, their spaceship growing more massive but shorter. Similarly, as they plunge into a black hole, doomed but enlightened readers can at least congratulate themselves on comprehending how extreme gravitation creates inescapably lethal tidal forces. Still, a perplexing mystery remains. Why does the singularity at the center of a black hole look irreconcilably different when viewed through quantum physics than it does when viewed through relativity? Undaunted, Bennett views this conundrum as the stimulus for scientific progress that will resolve it. Indeed, in the very fact that one man could formulate a theory as powerful as relativity, Bennett sees reason to hope that the entire human species can ultimately conquer stubborn nonscientific problems—social, political, even metaphysical. An impressively accessible distillation of epoch-making science. --Bryce Christensen