Science writer Panek (The 4 Percent Universe) examines evolving theories of gravity in this thought-provoking volume, rounding up "the usual suspects-Aristotle, Newton, Einstein" to reconstruct their preconceptions and interrogate their conclusions. From the rigid spheres-only cosmology of Aristotle, which forced mathematicians to try to manipulate "the math down here to match the motions up there," to Copernicus's equations introducing the "possibility that Earth was a planet like any other," to the experiments of Galileo establishing that a rolling ball "sped up at an unvarying rate," Panek demystifies early investigations of gravity with easy humor and a philosophical bent. In contemporary theories, readers learn "the velocity of light is finite in [James Clerk] Maxwell's equations, too, but it's also, crucially, something else: constant," which, in the 1860s, shifted the paradigm once again. Ultimately, he observes, Aristotle's view of the universe held sway for two millennia, while "Einstein's lasted less than a decade," thanks to the introduction of quantum mechanics. Panek's inquisitive, fine-tuned narrative is full of character and, unlike many other books on physics, imbued with the friendly casualness of a coffee-shop chat. As such, it will delight both lay readers and serious students. Agent: Henry Dunow, Dunow & Carlson Literary. (July) © Copyright PWxyz, LLC. All rights reserved.

The latest from Panek (The 4% Universe) is one of the best of the postgravitational-waves-discovery physics books for fans of popular science. Undeterred by Nobelist Kip Thorne amusedly telling him that the question "What is Gravity?" is meaningless, Panek proceeds to explore attempts to find an answer to the question. Beginning with myths from around the world that all differentiate between "down" here where we live and "up" there where there are stars, Panek progresses through key philosophical and scientific points made by Aristotle, John Philoponus, Nicolaus Copernicus, Galileo Galilei, Isaac Newton, Albert Einstein, Werner Heisenberg, and more. His journey through time is written in a conversational style with clear explanations. For example, he describes Galileo's main experiment with gravity: rolling balls of differing weights down various inclines. Panek makes clear that our understanding of gravity, and of the universe itself, is rapidly accelerating: "Aristotle's universe lasted 2000 years. Newton's…200 years. Einstein's less than a decade." VERDICT Teen and adult readers interested in better understanding the force of gravity and gaining insight into humanity's expanding knowledge of the universe will find this highly recommended book to be both accessible and enjoyable.--Sara R. Tompson, Lawrence, KS

According to this fine popular primer, nobody knows what gravity is, but few readers will feel that their time was wasted.No one thought about gravity before Aristotle, writes science writer Panek (The 4 Percent Universe: Dark Matter, Dark Energy, and the Race to Discover the Rest of Reality, 2011), but all ancient cultures knew that some things were "up" (the heavens, the gods), and earthly matter was "down." Everything on Earth fell down, but the heavens stayed up, and few thinkers wondered why. "Reasoning," writes the author, "was what Aristotle would introduce into the conversation: methodology, not mythology." However, he came to the wrong conclusion, maintaining that objects fell because they are drawn toward the center of the universe, which sat at the center of the Earth. Heavenly objects, being perfect, were exempt. Newton's concept of universal attractive force and the inverse square law were not original, but his outstanding mathematics, which predicted movements of bodies anywhere in the universe, made him a superstar in Britain. Natural philosophers of other nations pointed out that a force that acted magically across empty space was clearly nonsense. Because Newton's math worked so well, they came around, but plenty of thoughtful scientists remained unhappy. Panek paraphrases physicist and philosopher Ernst Mach: "the theory of gravitation had disguised its philosophical shortcomings by proving its reliability and usefulness. But the philosophical shortcomings remained. They'd just become respectable." Einstein solved the problem in 1915 by more dazzling mathematics demonstrating that matter warps nearby space-time. Bodies moving through this distorted space seem to change direction, giving the appearance of a force acting on them. Many bizarre consequencesblack holes, gravitational lenses, the slowing of timefollow naturally. Philosophically inclined readers may complain that scientists still don't know what gravity is, but the remainder will enjoy Panek's expert description of the spectacular things that gravity does.A useful primer on a force that still inspires mystery. Copyright Kirkus Reviews, used with permission.

The story Panek tells about falling off a chair in a bookstore will not displace the iconic tale of Newton watching an apple fall in his uncle's orchard. But, like the famous physicist's story, Panek's experience illustrates the power of gravity. But whereas the meaning of Newton's apple is summed up in a tidy inverse-square formula, Panek's bookstore mishap opens onto a mystery. For although scientists have grown astonishingly adept at measuring gravity, Panek compellingly establishes that they still cannot explain it. In probing the riddle of gravity, Panek carries readers from ancient Chinese creation myths through Einstein's relativity. But even with the stunning 2016 verification of Einstein's prediction of gravity waves, physicists still struggle to understand why gravity appears so different from other universe-pervading influences, such as the strong nuclear force and the electromagnetic force. No wonder some daring theorists are now advancing an audacious interpretation of gravity as the effect of an unseen parallel universe! Whether in orchard or bookstore, readers will never again regard falling objects without amazement!--Bryce Christensen Copyright 2019 Booklist