About a year ago, Riverhead Books published the Italian physicist Carlo Rovelli’s American edition of “Seven Brief Lessons on Physics.” A gentle book, it talked about physics in a way that even a poet could understand. “Reality Is Not What It Seems” goes deeper into the subjects of relativity and quantum mechanics, but is simultaneously aimed at the curious layperson while also useful to the modern scientist.
It includes diagrams and figures as clear and insightful as in the previous book. Rovelli still quotes Lucretius and Shakespeare and he continues to enjoy making literary allusions, especially, this time, to the Italian poet Dante. But in this more expansive book, instead of serving us a single equation as he did in “Brief Lessons,” Rovelli lets us nibble or gorge ourselves, depending on our appetites, on several scrumptious equations. He doesn’t expect everyone to be a master of the equations or even possess much mathematical acumen, but the equations serve as appetizers for those inclined to get their fill, so to speak.
Rovelli begins his story as any good story about physics begins in ancient Greece, with Democritus, Aristotle and Ptolemy. The drama of the discovery of the workings of the world evolves through the centuries with the classical physics of Copernicus and Newton, Michael Faraday and James Clerk Maxwell. The theories and equations of Albert Einstein, Paul Dirac and Werner Heisenberg; John Wheeler and Richard Feynman lead to Rovelli’s own account of the “current state of the search for our new image of the world.” About halfway through the book, Rovelli serves up a diagram that clearly shows how the concepts of space, time and particles have evolved into a modern, quantum mechanical world of spacetime and quantum fields.
In this book, especially in the latter part, Rovelli is more concerned than he was in the “Brief Lessons” with reconciling Einstein’s General Theory of Relativity with quantum mechanics. Rovelli writes, “General relativity taught us that space is something dynamic, like the electromagnetic field: an immense, mobile mollusk in which we are immersed, which stretches and bends. Quantum mechanics teaches us that every field of this sort is made of quanta, has a fine, granular structure.”
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Oddly enough, the seemingly opposite assumptions that are the cornerstones of general relativity and quantum mechanics contradict each other. But each theory enables physicists to make remarkably accurate predictions of how the universe and the tiniest things in it work.
Physicists often examine how things work in small scale first and then apply those discoveries to a universe. But classical mechanics is incomplete and fails to accurately predict what will happen when an electron falls straight into an atomic nucleus. Using classical mechanics, the universe would be infinitely squashed. In order to understand what happened fourteen billion years ago during the Big Bang, quantum gravity is required. Under quantum mechanics the universe is stable and cannot be infinitely squashed; it rebounds. Rovelli, a proponent of quantum “loop theory,” as opposed to “string theory,” says that the equations of loop quantum theory reveal that the Big Bang may have been more of a Big Bounce. Our universe may have been the result of the collapse of another universe, “passing across a quantum phase, where space and time are dissolved into probabilities.”
Rovelli contends that loop theory is more promising than string theory. Loop theory studies the quantum properties of space and time. But string theory attempts “writing a unified theory of all known fields, an objective that might be premature given current knowledge.”
Throughout this book, Rovelli continues to revel in the beauty of the universe. He tells us of how far we’ve come in understanding its mysteries, while reminding us how much we knew intuitively long ago. Thus, he quotes Feynman, who wrote, “all things are made of atoms,” which hearkens back to what Democritus contended more than two thousand years ago. Despite how much we know, Rovelli marvels at the vastness of a universe with so much yet to clarify and explore.
Joseph Peschel, a freelance writer and critic in South Dakota, can be reached at email@example.com
“Reality Is Not What It Seems”
By Carlo Rovelli, translated by Simon Carnell and Erica Segre
Riverhead Books, 288 pages