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Gravity's Engines How Bubble-Blowing Black Holes Rule Galaxies, Stars, and Life in the Cosmos

Caleb Scharf

Scientific American / Farrar, Straus and Giroux



Trade Paperback

272 Pages



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We’ve long understood black holes to be the points at which the universe as we know it comes to an end. Often billions of times more massive than the Sun, they lurk in the inner sanctum of almost every galaxy of stars in the universe. They’re mysterious chasms so destructive and unforgiving that not even light can escape their deadly wrath.

Recent research, however, has led to a cascade of new discoveries that have revealed an entirely different side to black holes. As the astrophysicist Caleb Scharf reveals in Gravity’s Engines, these chasms in space-time don’t just vacuum up everything that comes near them; they also spit out huge beams and clouds of matter. Black holes blow bubbles.

With clarity and keen intellect, Scharf masterfully explains how these bubbles profoundly rearrange the cosmos around them. Engaging with our deepest questions about the universe, he takes us on an intimate journey through the endlessly colorful place we call our galaxy and reminds us that the Milky Way sits in a special place in the cosmic zoo—a “sweet spot” of properties. Is it coincidental that we find ourselves here at this place and time? Could there be a deeper connection between the nature of black holes and their role in the universe and the phenomenon of life? We are, after all, made of the stuff of stars.


Praise for Gravity's Engines

“Mr. Scharf makes vivid the mind-boggling nature of the universe  . . . [there are] bright beams of knowledge coming from this excellent book.” —Wall Street Journal

"With Gravity's Engines, Caleb Scharf establishes himself as one of the finest space storytellers." —The Christian Science Monitor

"Using rich language and a brilliant command of metaphor, [Scharf] takes on some of the most intricate topics in theoretical and observational astronomical research. He weaves a wonderfully detailed tapestry of what modern astronomy is all about, from the complexities of cosmic microwave background studies to the X-ray mapping of galaxy clusters." —Nature 

"Stunning. I can't remember when I last read a popular science book where I learned as much I hadn't come across before."—Brian Clegg,

"Heady stuff, but luckily for readers . . . who lack a deep understanding of cosmology, Scharf populates his book with images and colorful metaphors."—David Wescott, The Chronicle Review

"An excellent overview of the state of black hole research . . . To explain why black holes are so important, Scharf provides a tour of much of modern astronomy and cosmology along with some requisite history, an impressive feat for such a relatively short book."—Matthew Francis, Ars Technica

"This heady story of astronomical endeavour and cosmic conjecture prompts a happy mix of marvels . . . That's the delight of this book, and all such accounts of discovery. They offer a reminder that, given an understanding of mathematical logic and some lenses with which to make a telescope, one accidental species on one inconsequential speck of matter in the 14 billionth year of the universe has been able to identify a few testable laws that govern matter and energy, and from these, and with an arsenal of ever more ingenious telescopes, build up a picture of things that happened far away and long ago, and from that begin to construct a story of everything."—Tim Radford, The Guardian

"Scharf provides a virtuosic history of the universe . . . He also serves as an appealing tour guide to the eerie, infinite corndors of the cosmos in which we reside."—Olivia Laing, Prospect

"Caleb Scharf is a lively and eloquent writer as well as a fine cientist. Gravity's Engines is particularly welcome because it presents topics at the frontiers of our understanding that have not hitherto been presented so clearly to a general readership."—Martin Rees, Emeritus Professor of Cosmology and Astrophysics, University of Cambridge, and author of Just Six Numbers and Our Final Hour

"To call this an absorbing read is an understatement. I felt dreamily transplanted . . . When I did emerge from the book to look up at the summer stars, the night seemed more brightly lit, slightly more known but also more awesome, more wonderfully strange." —The Barnes and Noble Review

"Scharf is a writer you'll gladly follow to the end of the universe." —Zocalo Public Square

"In Gravity's Engines, Caleb Scharf deftly tells you all you wanted to know about Black Holes, as well as all you never knew you wanted to know.  By the end of the book your conclusion will surely match mine: Black holes are terrifying yet awesome constituents of the cosmos." —Neil deGrasse Tyson, Director of the Hayden Planetarium at the American Museum of Natural History, author of Space Chronicles: Facing the Ultimate Frontier and Death by Black Hole: And Other Cosmic Quandries

“In Gravity’s Engines, Caleb Scharf tells the mind-blowing story of ‘supermassive’ black holes, the true masters of the Universe. Black holes are smaller than the Solar System yet project their power across the cosmos, sculpting entire galaxies of stars. They might appear esoteric and remote, but as Scharf explains, life on Earth may have been utterly impossible without them.” —Marcus Chown, author of Solar System and Solar System for iPad

“Caleb Scharf’s fun book takes you behind the scenes of the universe itself, to see how the celestial heavyweights we call ‘black holes’ help shape the cosmos.” —Sean Carroll, theoretical physicist at the California Institute of Technology, and author of From Eternity to Here

"Superbly accessible . . . Scharf’s breathtaking cosmic vision will appeal to anyone whose curiosity is aroused by gazing at a star-filled sky." —Booklist

“An intelligent explanation of a weird but essential feature of the universe . . . rich, satisfying.” —Kirkus Reviews 

"The subtitle of this most readable book about supermassive black holes exemplifies Scharf's playful tone...Highly recommended. Teen and adult fans of astronomy, as well as scientists looking for ways to explain black holes to nonscientists, will all enjoy this text." —Library Journal (starred review)

“Scharf’s explanations are vivid and accessible, evoking the awe of cosmic grandeur in a way that’s as humbling as it is fascinating.” —Publishers Weekly (starred review)

Reviews from Goodreads



Read an Excerpt

A computer sits among the coffee-stained papers scattered across my desk. Its screen has been blank all morning. Suddenly it lights up and displays a pixelated image. A message is coming in from space.
A few days earlier, high above Earth’s surface, a great orbiting observatory has stared for forty hours over the bows of the Milky Way galaxy. With chilled eyes it has patiently tracked a tiny patch of the cosmos, a speck of sky close to the constellation Auriga—the Charioteer. In this direction is a glorious view for a spotter peering into the
Read the full excerpt


  • Caleb Scharf

  • Caleb Scharf is the director of the Columbia Astrobiology Center. He writes the Life, Unbounded blog for Scientific American; has written for New Scientist, Science, and Nature, among other publications; and has served as a consultant for the Discovery Channel, the Science Channel, The New York Times, and more. Scharf has served as a keynote speaker for the American Museum of Natural History and the Rubin Museum of Art, and is the author of Extrasolar Planets and Astrobiology, winner of the 2011 Chambliss Astronomical Writing Award from the American Astronomical Society. He lives in New York City with his wife and two daughters.

  • Caleb Scharf Greg Barrett
    Caleb Scharf