To explain the disappearance of the largest land animals the earth has ever seen, Randall probes something that has never been seen: dark matter. More specifically, this acclaimed physicist argues that it was dark matter that nudged a comet earthward, so wiping out the dinosaurs 66 million years ago. As Randall unfolds the reasoning behind this bold speculation, she traverses an impressive range of science. Readers learn of the decisive role that dark matter—undetectable except for its gravitational pull—played in shaping galaxy clusters. They also learn about the dynamics of our own solar system, where our planet’s remarkable powers to sustain life may grow or diminish through the impact of objects from space. Widely publicized evidence that such an impact exterminated the dinosaurs gains astonishing new significance as Randall reinterprets it within her theory of how a disk of unusually interactive dark matter, insinuated in the heart of the Milky Way, unleashes a shower of meteoroids every 32 million years. Engrossing in its own right, this theory opens onto an illuminating survey of the cutting-edge science now deployed to test its components, including its daring redefinition of dark matter. As she did in Warped Passages (2005) and Knocking on Heaven’s Door (2011), Randall delivers intellectual exhilaration. — Bryce Christensen
REVIEW. First published September 15, 2015 (Booklist).