Dark Matter and the Dinosaurs

Starred review from September 7, 2015
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.

May 1, 2015

Dark matter: it's hard enough to understand as it is, and now Randall draws on original research to suggest a new kind. But as author of the recent New York Times best-selling Knocking on Heaven's Door, Harvard physicist Randall can talk to the less scientifically proficient. Here she theorizes that the huge comet that purportedly knocked out the dinosaurs and perhaps three-quarters of Earth's other species 66 million years ago was shaken from its orbit as the solar system passed through a disc of dark matter embedded in the Milky Way. With a 100,000-copy first printing.

Copyright 2015 Library Journal, LLC Used with permission.

Starred review from September 15, 2015
Randall (Theoretical Particle Physics and Cosmology/Harvard Univ.; Knocking on Heaven's Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World, 2011, etc.) explores the causes of the fifth major extinction event, which occurred 66 million years ago and wiped out terrestrial dinosaurs and three-quarters of all other species living on Earth.Dinosaurs dominated life on Earth for 135 million years. Geologists and paleontologists now agree that their relatively sudden extinction is attributable to the impact of a comet or asteroid hitting the Earth and precipitating major climate change. The author seeks to test her hypothesis that "a disk of dark matter in the plane of the Milky Way was responsible for triggering the meteoroid's fatal trajectory." For Randall, the role of dark matter in the evolution of the universe is the next scientific frontier. Dark matter constitutes 85 percent of the matter in the universe. It is not composed of atoms or electrons (the stuff of ordinary matter), and it does not interact with light or other radiation. We only know of its existence because of its measurable gravitational effects. Randall believes that it may have played a significant role in the existence of life on Earth not only by triggering a major climate-changing meteoroid collision, but by precipitating smaller impacts that deposited the heavy elements necessary for life (e.g., carbon) and possibly even amino acids. Now that the existence of the Higgs boson has been confirmed, the author is setting her sights on this exciting scientific area, which is built on the advances in scientific understanding of cosmic events over the past 50 years. Specifically, this involves establishing the possibility that there was a periodicity in the five extinction events reflective of still-unknown cosmic events possibly involving dark matter. Writing in a deceptively chatty narrative style, Randall provides a fascinating window into the excitement of discovery and the rigor required to test and elaborate new hypotheses. A top-notch science book from a leading researcher.

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Starred review from September 15, 2015
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 matterundetectable except for its gravitational pullplayed 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.(Reprinted with permission of Booklist, copyright 2015, American Library Association.)