Albert Einstein is often viewed as the icon of genius, and his theories are admired for their beauty and correctness. Yet the final judge of any theory is the rigorous test of experiment, not the fame of its inventor or the allure of its mathematics. For decades, general relativity has passed test after test with flying colors, including some remarkable new tests using the recently detected gravitational waves.

Still, there are reasons for doubt. Einstein's theory of gravity, as beautiful as it is, seems to be in direct contradiction with another theory he helped create: quantum mechanics. Until recently, this was considered to be a purely academic affair. But as more and more data pour in from the most distant corners of the universe, hinting at bizarre stuff called "dark energy" and "dark matter," some scientists have begun to explore the possibility that Einstein's theory may not provide a complete picture of the cosmos.

This book chronicles the latest adventures of scientists as they put Einstein's theory to the test in ever more precise and astonishing ways, and in ever more extreme situations, when gravity is unfathomably intense and rapidly churning. From the explosions of neutron stars and the collisions of black holes to the modern scientific process as a means to seek truth and understanding in the cosmos, this book takes the reader on a journey of learning and discovery that has been 100 years in the making.

About the Author:
Clifford M. Will is a world-leading theorist in the verification of general relativity, black holes and gravitational waves. He received his Ph.D. in 1971 from Caltech, and has been on the faculty of Stanford, Washington University and the University of Florida, where he is currently Distinguished Professor. Will has written numerous popular articles and four books, including Was Einstein Right? in 1986, which received many accolades. He is a member of the US National Academy of Sciences, a Fellow of the American Physical Society and of the American Academy of Arts and Sciences, and recipient of the American Physical Society's 2021 Einstein Prize.

Nicolás Yunes is Professor of Physics at the University of Illinois at Urbana-Champaign and Founding Director of the Illinois Center for Advanced Studies of the Universe. Before joining Illinois, he was an Associate Professor at Montana State University, where he co-founded the eXtreme Gravity Institute. He is the author of several review articles on tests of General Relativity and over 170 research papers. He is also the producer of the Celebrating Einstein science festival, the Rhythms of the Universe spoken word event, and the Einstein's Gravity Playlist planetarium show. He is a leader in the use of gravitational wave observations to systematically test Einstein's theory of General Relativity, and is an internationally recognized expert in other aspects of gravity, including black holes and neutron stars. He has received the Young Scientist Prize of the International Union of Pure and Applied Physics.