An Intuitive Introduction to Einstein's Ideas, and Why They Matter
December 2, 2013
“Black holes don’t suck,” says astrophysicist Bennett (Life in the Universe); in fact, their exotic nature is the perfect way to explore relativity. The special theory of relativity, proposed by Albert Einstein in his 1905 paper, “On the Electrodynamics of Moving Bodies,” says in part that nothing can outrace light, but it’s exactly in that highly accelerated realm where you need to be to observe the extreme weirdness of relativity at work: time dilation, mass increasing, and the shortening of the length of high-velocity objects. Bennett shows how particle accelerators can provide that environment on Earth, making special relativity “one of the most well-tested theories in all of science”—but still incomplete, as far as Einstein was concerned. He sought “an underlying simplicity in the universe”—wherein gravity and acceleration are the same—and he found that in the curved spacetime of general relativity where orbiting objects move “like marbles in a salad bowl,” following the curvature of spacetime along the straightest possible path. From black holes and gravity waves, to wormholes and warp drive, Bennett’s fun book shows readers what relativity means, and what it reveals about our universe.
March 1, 2014
The theory of relativity is one of those areas of science that seems daunting to non-physicists. Although the experts agree that the theory is accurate and eloquent, most literature explaining it is too complex for the lay reader to grasp fully. Bennett (Beyond UFOs), an astrophysicist who has coauthored many science textbooks, tries a different approach. First, he keeps the math out of it. The only equation in the book is E=mc2. Instead he relies heavily on thought experiments. Einstein himself used thought experiments to understand how to make sense of the shortcoming of Newtonian physics. Bennett takes the reader step by step from the special theory of relativity through the broader general theory of relativity. At each step he starts with what is known to us more or less through common sense and then moves slowly into new material. For example, he uses an intuitive concept like the earth being round to help explain how space-time can be curved, a concept that may not be intuitive. A generous dose of graphs and charts also helps illuminate his discussion. VERDICT Bennett does a masterly job of teaching a difficult topic without oversimplifying it. The results are recommended for readers at the high school level and above. A general understanding of Newtonian physics is beneficial.--William Baer, Georgia Inst. of Technology Lib., Atlanta
Copyright 2014 Library Journal, LLC Used with permission.
January 15, 2014
Understanding the universe requires understanding relativity, and this slim volume does an admirable job without resorting to the gimmicks or magic show common in the Einstein-for-laymen genre. "Much of the difficulty that most people have with relativity," writes astrophysicist Bennett (Math for Life: Crucial Ideas You Didn't Learn in School, 2012, etc.), "comes about only because it seems to run counter to ideas of space and time that have become deeply ingrained in our minds." What's relative in relativity, he writes, is motion. Its foundation rests on two absolutes: 1) The laws of physics are the same for everyone and, 2) the speed of light is the same for everyone. Readers will share Bennett's amazement at the weird consequences of the latter. The faster an object moves, the more its length contracts, its mass increases, and time slows. If it reaches the speed of light, which is impossible, time would stop. These are facts, and experiments verify them. Modern technology, such as GPS measurements, must take relativity into account. Bennett begins with special relativity, which explains constant motion. It's so simple that the required math does not go beyond high school algebra. Far more complex, general relativity explains accelerated motion, which is (another Einstein discovery) identical to gravity. Laymen describe gravity as an attraction between objects. Scientists since Isaac Newton agreed, but all hated the idea of an invisible force acting across empty space. Einstein solved this problem by revealing that gravity is the natural consequence of curved space. The greater the mass of a body, the more it warps nearby space into a fourth dimension: time. We can't see this dimension, so it appears that heavenly bodies are moving in odd directions when they're simply following the straightest path through spacetime. A sober, comprehensible account of what every intelligent layman should know about space and time.
COPYRIGHT(2014) Kirkus Reviews, ALL RIGHTS RESERVED.
Starred review from February 1, 2014
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 principlesthe uniformity of natural law and the invariance of the speed of lightreaders 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 problemssocial, political, even metaphysical. An impressively accessible distillation of epoch-making science.(Reprinted with permission of Booklist, copyright 2014, American Library Association.)