Einstein’s Monsters: The Life and Times of Black Holes

306 Pages·2018·31.64 MB·English

by  Chris Impey

To Dinah,
My love and inspiration.
Stars, hide your fires; Let not light see
my dark and deep desires.
WILLIAM SHAKESPEARE,
MACBETH, ACT 1, SCENE 4
CONTENTS
ACKNOWLEDGMENTS
FOREWORD
PART A. EVIDENCE FOR BLACK HOLES, LARGE AND SMALL
1. The Heart of Darkness
An English Clergyman Imagines Dark Stars
A Great French Mathematician Weighs In
Understanding the Fabric of Space-Time
A Singularity and a Life Cut Short
The Master of Implosions and Explosions
Coining the Perfect Term for the Inscrutable
A Genius Struggles with Gravity and Disease
Betting on Black Holes
The Golden Age of Black Hole Theory
2. Black Holes from Star Death
The Forces of Light and Darkness
Gravity and Darkness Are the Final Victors
Finding the First Black Swan
Weighing the Invisible Dance Partner
Black Holes with Gold-Plated Credentials
Using Gravitational Optics
Physics at the Edge of the Maelstrom
A Tour of the Binary Star Bestiary
3. Supermassive Black Holes
The Only Radio Astronomer in the World
Galaxies with Bright Nuclei
Radio Astronomy Comes of Age
A Dutch Astronomer Discovers Quasars
Astronomers Harvest Distant Points of Light
Hypothesizing Massive Black Holes
Mapping Radio Jets and Lobes
The Zoo of Active Galaxies
A Matter of Perspective
4. Gravitational Engines
The Big Black Hole Next Door
Stars at the Edge of the Abyss
The Dark Core in Every Galaxy
Baron Rees of Ludlow Tames the Beast
Using Quasars to Probe the Universe
Weighing Black Holes by the Thousand
Accretion Power in the Cosmos
Massive Black Holes Are Not Scary
PART B. BLACK HOLES, PAST, PRESENT, AND FUTURE
5. The Lives of Black Holes
Seeds of the Universe
First Light and First Darkness
Black Hole Birth by Stellar Cataclysm
Finding the Missing Links
Simulating Extreme Gravity in a Computer
How Black Holes and Galaxies Grow
The Universe as a Black Hole
Making Black Holes in the Lab
6. Black Holes as Tests of Gravity
Gravity from Newton to Einstein and Beyond
What Black Holes Do to Space-Time
How Black Holes Affect Radiation
Inside the Iron Curtain
X-Rays Flickering Near the Abyss
When a Black Hole Eats a Star
Taking a Black Hole for a Spin
The Event Horizon Telescope
7. Seeing with Gravity Eyes
A New Way of Seeing the Universe
Ripples in Space-Time
An Eccentric Millionaire and a Solitary Engineer
When Black Holes Collide
The Most Precise Machine Ever Built
Meet the Maestro of Gravity
Viewing the Universe with Gravity Eyes
Collisions and Mergers of Massive Black Holes
Gravity and the Big Bang
8. The Fate of Black Holes
The New Age of Gravity
Quasar on Our Doorstep
Merging with Andromeda
The Biggest Black Holes in the Universe
The Era of Stellar Corpses
A Future of Evaporation and Decay
Living with Black Holes
NOTES
INDEX
FOREWORD
Black holes are the best known and least understood objects in the universe. The
term is used colloquially to talk about an entity that sucks in everything around
it. Black holes appear onscreen and in fiction; they’ve been co-opted by pop
culture. A black hole is shorthand for something enigmatic, with a sinister edge.
I call them “Einstein’s monsters” as a metaphor. They are powerful and beyond
anyone’s control. Einstein did not create black holes, but he developed the best
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theory of gravity that we have for understanding them.
What most people think they know about black holes is wrong. They’re not
cosmic vacuum cleaners, sucking in everything in the vicinity. They only distort
space and time very close to their event horizons. Black holes represent a small
fraction of the mass of the universe, and the nearest examples are several
hundred trillion miles away. It’s unlikely that they can be used to time-travel or
visit other universes. Black holes aren’t even black. They emit a fizz of particles
and radiation and most are part of binary systems where gas falling in heats up
and glows intensely. Black holes aren’t necessarily hazardous. You could fall
into the black hole at the center of most galaxies and not feel a thing, although
you’d never get to tell anyone what you saw.
This book is an introduction to black holes, large and small. Black holes are
deceptively simple, but the math needed to understand them is fiendishly
complex. We’ll meet scientists who revealed black holes to humankind, from
theorists who dared dream of dark stars hundreds of years ago to those who
wrestled with general relativity, and beyond.
Black holes cannot be understood without Einstein’s theory of general
relativity, developed a century ago, which says that space and time are distorted
by matter. In the extreme case where mass is highly concentrated, a region of
space is “pinched off” from the rest of the universe and nothing can escape, not
even light. That’s a black hole. But even Einstein was skeptical of their reality.
He was not alone; many notable physicists doubted that they existed.
They do exist. Evidence has accumulated for forty years that when massive
They do exist. Evidence has accumulated for forty years that when massive
stars die, no force in nature can resist the gravitational collapse of their cores. A
gas ball 10 times the size of the Sun crunches down to a dark object the size of a
small town. More recently, it’s become clear that the center of every galaxy
contains a massive black hole, ranging in mass over a factor of a billion.
Examining where black holes live, we’ll learn about binary systems, where a
black hole is in a gravitational waltz with a normal star. We’ll see that the best
evidence for any black hole is at the center of our own galaxy, where dozens of
stars swarm like angry bees around a dark object 4 million times the mass of the
Sun. When the massive black holes that all galaxies harbor rouse from their
slumber and begin feeding, they can be seen across distances of billions of light
years. These gravitational engines are the most powerful sources of radiation in
the universe.
Recently, physicists have learned to see with “gravity eyes” by detecting
gravitational waves. When two black holes collide, they release a cymbal clash
of ripples in space-time that race outward at the speed of light and contain
information about the violent encounter. A new window has opened onto black
holes and all situations where gravity is strong and changing. Gravitational
waves provide unequivocal proof, if any were still needed, that nature makes
black holes. Every five minutes, a pair of black holes merges somewhere in the
universe, pouring gravitational waves out into space.
We’re far from knowing everything there is to know about black holes. They
continue to surprise and delight. Black holes allow general relativity to be tested
in new ways. Nobody knows if these tests will affirm the theory or lead to its
downfall. There is vigorous debate over information loss in black holes and
whether or not the information is somehow coded on the event horizon.
Theorists hope that black holes may be places where string theory can be
verified, finally realizing Einstein’s quest to unify quantum mechanics and
general relativity.
This book has two parts. The first covers the evidence we have that black
holes exist. This evidence spans a range of black holes, from those not much
more massive than the Sun to leviathans the mass of a small galaxy. The second
explains how black holes are born and die. It also explains how black holes push
our theories of nature to the limit. Along with the stories of black holes, there are
personal stories, including some of my own, as a reminder that while science is
dispassionate, scientists are made of flesh and blood, with all the flaws and
foibles that entails. As I am covering research in a fast-moving subject, some
results quoted here may not stand the test of time. Any resulting errors,