Using accessible writing and vivid examples, Randall (Higgs Discovery), a theoretical particle physicist and cosmologist at Harvard University, examines the indirect role dark matter may have played in the extinction of the dinosaurs, as just one example of the unlikely connections to be found in the universe. She builds her argument methodically, moving from discussions of the big bang and galaxy formation, through prehistoric extinction events, and into the way dark matter interacts with other forces and particles. Scientists detect dark matter indirectly, Randall says. In space, a massive object bends light as it zips past, so that object’s mass can then be determined by measuring the bend. Its gravity can also perturb the motion of other bodies passing through the area. Randall proposes the existence of a dense disk of dark matter inside the galactic disk of the Milky Way. As stars—including our sun—rotate around a galactic center, they and their planets cross the dark disk. On Earth’s pass-through, the dark disk’s gravity could have perturbed an icy rock in the Oort Cloud, sending it on a collision course with Earth. Randall covers a lot of ground, but does so smoothly even when addressing some of science’s most abstruse subjects. Hers is a fascinating, tantalizing theory, linking life on Earth—or the extinction thereof—with the very origins of our universe. (Nov.)


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