Gravity's Century: From Einstein's Eclipse to Images of Black Holes

by Ron Cowen

Overview

A sweeping account of the century of experimentation that confirmed Einstein’s general theory of relativity, bringing to life the science and scientists at the origins of relativity, the development of radio telescopes, the discovery of black holes and quasars, and the still unresolved place of gravity in quantum theory.

Albert Einstein did nothing of note on May 29, 1919, yet that is when he became immortal. On that day, astronomer Arthur Eddington and his team observed a solar eclipse and found something extraordinary: gravity bends light, just as Einstein predicted. The finding confirmed the theory of general relativity, fundamentally changing our understanding of space and time.

A century later, another group of astronomers is performing a similar experiment on a much larger scale. The Event Horizon Telescope, a globe-spanning array of radio dishes, is examining space surrounding Sagittarius A*, the supermassive black hole at the center of the Milky Way. As Ron Cowen recounts, the foremost goal of the experiment is to determine whether Einstein was right on the details. Gravity lies at the heart of what we don’t know about quantum mechanics, but tantalizing possibilities for deeper insight are offered by black holes. By observing starlight wrapping around Sagittarius A*, the telescope will not only provide the first direct view of an event horizon—a black hole’s point of no return—but will also enable scientists to test Einstein’s theory under the most extreme conditions.

Gravity’s Century shows how we got from the pivotal observations of the 1919 eclipse to the Event Horizon Telescope, and what is at stake today. Breaking down the physics in clear and approachable language, Cowen makes vivid how the quest to understand gravity is really the quest to comprehend the universe.

Product Details

ISBN-13:	9780674974968
Publisher:	Harvard University Press
Publication date:	05/06/2019
Pages:	192
Sales rank:	1,036,272
Product dimensions:	5.80(w) x 8.30(h) x 0.90(d)

About the Author

Ron Cowen has written for National Geographic, Nature, the New York Times, Science, Science News, Scientific American, and U.S. News & World Report, and is a guest commentator on NPR’s Science Friday. He has twice received both the American Institute of Physics’s Science Writing Award and the American Astronomical Society (Solar Physics Division)’s Popular Writing Award.

Table of Contents

Introduction 1

1 Genesis 7

Deeper Dive: Space and Time, a Perfect Union 19

Deeper Dive: Testing the Equivalence Principle before Einstein 21

2 From Turmoil to Triumph 25

Deeper Dive: Riemann's Work and the Metric Tensor 43

Deeper Dive: The Meaning of Einstein's Equation 45

3 Eddington on a Mission 47

Deeper Dive: A History of Light Bending 66

Deeper Dive: A Modern-Day Solar Eclipse 68

4 Expanding the Universe 69

5 Black Holes and Testing General Relativity 83

Deeper Dive: New Tests of Einstein's Theory 92

6 Quantum Gravity 99

Deeper Dive: Black Holes and the Information Paradox 114

7 Hearing Black Holes 121

Deeper Dive: LIGO and Beyond 135

Deeper Dive: Gravitational Waves Lost and Found 141

8 Imaging Black Holes 147

Deeper Dive: A History of Illustrating Black Holes 159

Source Notes 163

Further Reading 167

Acknowledgments 173

Index 175

Editorial Reviews

★ 03/11/2019

This gracefully written history of 20th-century gravity research from science writer Cowen shines a light on a key aspect of modern physics. As he explains, the current view of gravity began with a young Albert Einstein’s curiosity about what a beam of light might look like. Cowen describes how Einstein eventually published the theory of general relativity in 1916, predicting how gravity would bend light. Proving this required photographing a solar eclipse in 1919 and seeing whether, as the theory predicted, the stars whose rays pass close to the sun would seem to shift position. When astronomer Arthur Eddington announced the photos showed that the sun’s gravity did indeed bend light, Einstein became the world’s first “science superstar.” Cowen shows how successive generations of physicists have worked to understand gravity, exploring research that showed the universe was expanding (a conclusion Einstein initially resisted); observing this, and the rotation of galaxies, gave physicists their first clues about dark energy and dark matter. Other phenomena touched on include black holes, gravity waves, and even wormholes. Filled with vivid descriptions of cutting-edge work and the scientists behind it, Cowen’s book is fascinating, both a learning experience and a pleasure to read. (May)

Publishers Weekly

A brief, accessible account of the 1919 eclipse and subsequent advances in cosmology, touching upon dark matter, dark energy, quantum gravity, and black holes. It’s a very quick and readable introduction to some of the exotic findings that came in Einstein’s wake.

Bookforum

A clear and compelling narrative about the development of our understanding of gravity and the universe, powered by Einstein and his cohorts. Cowen weaves together the historical and personal events leading to this revolution and brings us up to date with the ideas and speculations that will likely forge an even newer and more radical understanding of the nature of the world.

George F. Smoot

Gravity’s Century is remarkably easy to follow and read. If you are a keen beginner, or just interested in some of the people behind the science, read this book.

BBC Sky at Night - Laura Nuttall

Clear and readily intelligible to the non-specialist.

Well-Read Naturalist - Johannes E. Riutta

Cowen is a gifted science writer and storyteller, and the story is amazing!

John C. Mather

Its informal, readable style hides an enormous amount of physics and a fair share of history.

Choice

In a conversational style, the veteran physics writer chronicles the field’s greatest hits in the century since a solar eclipse proved Einstein was right.

Discover - Gemma Tarlach

[Cowen’s] brisk, engaging narrative leads us from Einstein’s famous ‘thought experiments’ through theorists’ many (so far unsuccessful) attempts to marry quantum mechanics with general relativity, and up to recent (more successful) efforts to observe gravitational waves and black holes.

Wall Street Journal

A breezy and enjoyable read, a welcome addition to a crowded shelf of books on these topics.

Nature - Peter Coles

There are some extremely clever ways to visualize how gravitation works in a Universe governed by General Relativity under a wide variety of physical conditions, and Cowen explores many of the classic ways you've probably seen before along with some incredibly creative ones that were new, even to me.

Ethan Siegel

This is as good a short introduction to Einstein’s thought as one could wish for.

The Spectator - Simon Ings

Einstein’s general theory of relativity radically changed our notions of space, gravity, and time. Gravity’s Century takes us from Einstein’s struggle to develop his theory up to the modern day—when the detection of gravitational waves from black holes has confirmed general relativity’s most audacious claims, even as scientists are still trying to reconcile the theory with the other great idea of twentieth-century physics, quantum mechanics.

David Spergel

[An] enjoyable read…Cowen does a good job of breaking down ideas so that they are easily understood…I would recommend Gravity’s Century to anyone with an interest in astrophysics in general, or in gravitation in particular.

Metascience - Earl Patrick Bellinger

Accessible and compact…A great introduction to Einstein’s theory of general relativity and the century of research that has been testing his ideas since.

Inquisitive Biologist - Leon Vlieger

A concise chronicle of the dramatic expansion of our knowledge of the universe, from the eclipse expeditions of 1919 to test Einstein’s theory of relativity, to the Event Horizon Telescope’s black hole images of 2019.

Symmetry - Mike Perricone

[Cowen’s] brisk, engaging narrative leads us from Einstein’s famous ‘thought experiments’ through theorists’ many (so far unsuccessful) attempts to marry quantum mechanics with general relativity, and up to recent (more successful) efforts to observe gravitational waves and black holes.

Wall Street Journal

2019-02-13

A brief history of the past 100 years of experimentation related to Einstein's theory of relativity, black holes, and more.

The 100th anniversary of the 1919 eclipse photographs that showed the sun's gravity bending light waves and made Einstein a superstar has not gone unnoticed, so readers seeking a primer on relativity can choose from a rush of popular books, which includes this slim, earnest account. What's relative in relativity is motion, explains science writer Cowen. No matter how an observer moves, the laws of physics and speed of light never change. This sounds trivial, but the consequences are bizarre. In his 1905 discovery of special relativity, Einstein proved that time passes more slowly and objects grow heavier as they move faster. Time would stop and an object's weight become infinite at the speed of light, so this is an unreachable limit. Special relativity is easy; only high school math is required, but it only applies to steady motion. Einstein's general relativity theory of 1915 explained all motion, which includes acceleration and gravity. This formulation turned out to be wildly difficult. The math was so complicated that Einstein needed a mathematician friend's help. Cowen delivers a solid history of relativity's past 100 years. He works diligently and sometimes successfully to describe concepts such as curved space, black holes, gravitational waves, and dark energy. Most popular accounts admit that relativity explains the macroscopic universe but fails at the atomic level, which follows laws of the century's other great breakthrough in physics: quantum mechanics. Physicists are working hard to reconcile the two theories; none of many ingenious hypotheses have stood up, and Cowen's imaginative efforts to explain them are only partially successful—but this is not an area where popular writers excel.

A fine introduction to the basics—if not the complexities—of relativity.

Kirkus Reviews

John Patrick Walsh’s clear and upbeat narration leads listeners through a concise overview of Einstein’s theories of special and general relativity. These are a challenge in audio since concepts like acceleration, gravity, and space-time are more easily understood visually. The audiobook compensates by including a pdf of informative graphics, some illustrating how space-time is warped by heavy planets. Walsh’s performance enlivens the chapter on astronomer Arthur Stanley Eddington’s thrilling, and nearly thwarted, race to prove general relativity using photographs of a solar eclipse. Walsh’s overall tone of animated excitement is appropriate for depicting the greatest scientific discoveries of the last century. Ending with a fascinating exploration of the most recent research on black holes, the audiobook leaves listeners giddily contemplating a universe cracked open by the brilliant mind of Albert Einstein. J.T. © AudioFile 2019, Portland, Maine

AUGUST 2019 - AudioFile