This book tells the story of the experimental aspects of relativity. As Will writes in his preface, "It is about an intensive twenty-year effort, beginning around 1960, to check the predictions of general relativity accurately, and to find new predictions to check." The main question posed by the book— Was Einstein Right?—is answered by looking at the experimental evidence amassed over the last 80 years.
Will begins by confronting the myth that relativity is understood by only a few people. Everyone wants to understand but the problem is that existing literature either tells parables about ants living on apples or shows that relativity is "just another spin two classical field." By solidly planting his feet in the domain of experiments, Will explains relativity by illustrating the differences in the physical worlds described by Einstein and Newton. And in doing so, he hacks away at the belief that Einstein was an intellect beyond comprehension as he stood in front of a blackboard filled with funny symbols.
While the Einstein legend was growing in the first quarter of the 20th century, relativity was experiencing a 35-year lull. As Will explains, a significant part of the revival that began around 1960 was the discovery of astrophysical objects that required relativity for a full description—the superenergetic and supermassive quasars that derive their power from gravity; the superdense pulsars that spin at relativistic speeds; and the 3-degree microwave background, the remnant of the primeval fireball. Will's descriptions provide the reader with the opportunity to encounter many of the phenomena that made astrophysics so exciting over the past decades. It is truly an added advantage of the book.
The book is weakest when the author becomes cute, telling us where he was standing in his short pants while scientists were working on problems in the late 1950s and early 1960s. It is at its best when Will describes the later work and modern experiments.
I loved reading the story of the discovery of the binary pulsar, two neutron stars that move at a tenth of the speed of light in an orbit that is the size of the sun! Irwin Shapiro's dogged determination to use spacecraft and radar ranging of the planets to test general relativity also made a good story, particularly since I was surprised to learn that the time delay of light signals in gravitational potentials wasn't known to be a feature of general relativity before Shapiro's work of 20 years ago.
Will is already known for his clear and systematic treatment of rival theories of gravity. He shows equal clarity here in this exposition of the experimental aspects of relativity. The book is a must buy for all those scientists who have had an unopened copy of Gravitation or another general relativity text on their shelves for over a decade.