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Copyright © 2018 by Alanna Mitchell
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LIBRARY OF CONGRESS CATALOGING-IN-PUBLICATION DATA
Names: Mitchell, Alanna, author.
Title: The spinning magnet : the electromagnetic force that created the modern world—and could destroy it / Alanna Mitchell.
Description: New York, New York : Dutton, an imprint of Penguin Random House, LLC, [2018] | Includes bibliographical references and index.
Identifiers: LCCN 2017034554| ISBN 9781101985168 (hardcover) | ISBN 9781101985182 (ebook)
Subjects: LCSH: Electromagnetism. | Magnetic fields. | Earth (Planet)—Mantle. | Geomagnetism. | Solar radiation—Health aspects.
Classification: LCC QC760 .M5425 2018 | DDC 538/.7—dc23
LC record available at https://lccn.loc.gov/2017034554
While the author has made every effort to provide accurate telephone numbers, Internet addresses, and other contact information at the time of publication, neither the publisher nor the author assumes any responsibility for errors or for changes that occur after publication. Further, the publisher does not have any control over and does not assume any responsibility for author or third-party websites or their content.
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contents
Title Page
Copyright
Dedication
PREFACE
Playing with the Universe
PART I
magnet
CHAPTER 1
The Beginnings of Things
CHAPTER 2
The Unpaired Spinning Electron
CHAPTER 3
Parking in the Shadow of Magnetism’s Forgotten Man
CHAPTER 4
Into Whose Embrace Iron Leaps
CHAPTER 5
Revolutions on Paper
CHAPTER 6
The Earth’s Magnetic Soul
CHAPTER 7
Voyage into the Underworld
CHAPTER 8
The Greatest Scientific Undertaking the World Had Ever Seen
CHAPTER 9
The Rock That Turned the World Upside Down
PART II
current
CHAPTER 10
Experiment in Copenhagen
CHAPTER 11
A Very Intimate Relationship
CHAPTER 12
Jars Full of Lightning
CHAPTER 13
The Apothecary’s Son
CHAPTER 14
The Bookbinder’s Apprentice
CHAPTER 15
Magnets Making Currents
CHAPTER 16
The Lines That Fill the Air
PART III
core
CHAPTER 17
The Contorting Gyre
CHAPTER 18
Shocks Inside the Earth
CHAPTER 19
Pharaohs, Fairies, and a Tar-Paper Shack
CHAPTER 20
Zebra Skins Under the Sea
CHAPTER 21
At the Outer Edge of the Dynamo
CHAPTER 22
Anomaly to the South
CHAPTER 23
The Worst Physics Movie Ever
CHAPTER 24
The Great Hazardous Spinning Sphere of Sodium
PART IV
switch
CHAPTER 25
Looking Up
CHAPTER 26
Horrors the Lights Foretold
CHAPTER 27
Lethal Patches
CHAPTER 28
The Cost of Catastrophe
CHAPTER 29
Trout Noses and Pigeon Beaks
CHAPTER 30
A Suit of Stiff Black Crayon
Notes
Selected Bibliography
Acknowledgments
Index
About the Author
PREFACE
playing with the universe
Night had set in by the time the green lights started dancing in the skies. I was in a canvas tent, trying to sleep in the bone-chilling cold of the late Arctic summer, worried about hungry polar bears. The cries of my fellow travelers roused me and I cursed, pulling on snow pants, boots, and a warm jacket before facing the night air.
The aurora borealis, or northern lights, were coursing through the black heavens, pulse after pulse of neon green against the scatter of stars, so near it was as if the curtain of light embraced us. They would fade away. We would hold our breath. And then back they would swoop, suffusing the sky. The heavens writhed with the otherworldly green rays, on and on, as if they held sway not just over our planet but over time too.
Watching those neon northern lights, I was closer than I knew to some of those who shared my impulse to understand the planet’s magnetic force. My camping spot was on King William Island in the Canadian Arctic, about 100 miles or so from the Boothia Peninsula, where the British explorer James Clark Ross first pinpointed the Earth’s magnetic north pole in 1831. His discovery of it was part of the magnetic crusade, the most sustained and impassioned scientific campaign the world had seen until then. At that time, the might of nations depended on naval prowess and efficient trade on the seas. And that depended on the magnetic compass. There was a trick to seafaring navigation, though. Knowing where you were depended on being able to adjust for the difference between magnetic north, where the compass pointed, and geographical north. The scientific world was united in an obsessive effort to figure out a formula that would allow sailors to know their coordinates more exactly. That required understanding the strange force that pulled the compass. And that demanded information from the top and bottom of the Earth, where the force showed itself most strongly.
King William Island itself resonates with a grisly piece of the magnetic quest. It is where the British explorer Sir John Franklin vanished in the 1840s along with his 128 men and their two ships. They were trying to complete the Northwest Passage, the quick sea route over the top of North America that would connect the wares of the Orient with the markets of Europe. But Franklin was also a player in the magnetic crusade. The ships in his Arctic adventure, HMS Erebus and HMS Terror, carried enough equipment to set up a state-of-the-art magnetic observatory in the Arctic, one of dozens that were being established all over the world as scientists tried to decode the secrets of the magnet. Franklin himself orchestrated the setting up of a magnetic observatory on the island we now know as Tasmania, off the Australian mainland’s south coast.
But when his Arctic ships got stuck in the ice and Franklin died, along with many of his men, the survivors abandoned ship and took to the frozen island in their leather-soled shoes and navy cloth greatcoats in a bid to walk to safety with the Earth’s magnetic field as their trusted guide. Some resorted to cannibalism. All died. Few of their skeletons have been recovered. It was the worst disaster to hit Arctic exploration. The Inuit who live on King William Island say the sailors’ ghosts h
aunt the place still. Among the relics recovered from the sailors’ doomed march was a brass pocket compass, currently in the collection of the National Maritime Museum in Greenwich, England. The men were trying to read their magnetic position even in those grim final days. It was their last hope to get home.
Franklin, Ross, and other Victorian explorers, stuck for years on end in the Arctic, undoubtedly saw the northern lights. But they could not have known how the compass, the magnetic poles, and the auroras fit together. Today, we know that they are facets of one another. The Earth is a giant magnet with its own two poles, north and south. Stretchy magnetic field lines leave the surface of the Earth at the south magnetic pole; run around the planet, where they interact with the magnetic fields of the sun and the galaxy; and then reenter the Earth at the north magnetic pole in unending, erratic loops.
Our magnetic field is generated in the Earth’s most secret inner reaches—its hot, yet frozen, metal inner core surrounded by a liquid metallic outer core. That heat, a remnant of the planet’s violent birth, is the secret to the planet’s magnetic power. The core has been on a multibillion-year quest to get rid of that heat from the inside out and is shedding it through convection. Convection generates electrical currents in the molten metal of the part of the core that is not yet solid, and those currents produce a magnetic field. Phoenix-like, that field is continually being created and destroyed. It stretches out for thousands of miles into space, our planet’s giant defense system against the lethal invisible rays and charged subatomic bits that would otherwise rip through living tissue and tear away the Earth’s atmosphere. Consider that our sister planet, Mars, lost its atmosphere, water, and likely any life forms when its internal magnetic field died billions of years ago.
A compass, with its magnetized needle, is responding to the Earth’s magnetic field. And the auroras? To humans, the magnetic field is invisible and imperceptible. We see the effects of the Earth’s field, for example, when a compass needle moves. But many species actually perceive the magnetic field. Some scientists call it a magnetic sixth sense that is like sight or touch, just more poorly understood and more complex. Creatures from bacteria to spiders to squids to sea turtles to almost everything with a backbone somehow use the magnetic field to navigate; it’s one way they find food, mates, homes. Birds, though, are in a class of their own when it comes to perceiving magnetism. One study found that they can just open their eyes and see it, the way we see light. Biologists believe that humans once had the ability to sense the field the way other vertebrates still do. Vestiges of it are knitted into our genetic makeup, albeit dormant. But mostly we walk around unaware of this hidden force field that has such an effect on our lives and our world.
The exception is the auroras. They usually appear in great oval rings around the top and bottom of the planet. Occasionally they show up closer to the equator. They are magnetism briefly made visible, the product of violence in outer space perpetrated by plasma that has roared at us from the sun. That plasma, also known as solar wind, has a magnetic field of its own, and when it is directed in a certain way, it can tear open the Earth’s magnetic field. Solar wind rushes in along the loops of the Earth’s magnetic field, pouring fast-moving, highly energized atomic particles into the polar regions, where they crash into oxygen and nitrogen atoms in the Earth’s upper atmosphere. In turn, the solar wind’s ferocious energy is transmitted to the oxygen and nitrogen atoms, exciting them. As the atoms relax back to normal, they shed their extra energy as light and color. The green northern lights I saw were excited oxygen atoms frolicking in the sky, showcasing the Earth’s own magnetic field. It was like looking into the sky to see a reflection of the machinations of the bowels of our planet.
For thousands of years, men and women have struggled to understand what magnets mean. They have looked to the heavens, not because they thought the aurora or the celestial bodies could provide clues about magnetism but because they thought that the heavens were the Earth’s puppeteers. If they looked closely enough at the stars, they would be able to read whatever they needed to about our planet. Painstakingly, through experimentation and flashes of inspiration and, finally, math and theoretical physics, they built up the conceptual understanding of magnetism we have today. It is highly abstract. It is ardently creative. It is slightly imperfect. But it is powerful.
And revelatory. It tells us the surprising news that we need to pay close attention to what used to be called our planet’s magnetic soul. The Earth’s magnetic power is on the move. That power is eccentric and, therefore, so are its poles. Eventually, the covert intrigues within the Earth will become so violently disruptive that they will force the poles to switch places. We know this because it has happened hundreds of times in the planet’s history. The last time, 780,000 years ago, our species was not yet on the planet. But the long string of pole flips has left traces buried in the seams of the plates that fashion Earth’s crust and in some of the rocks and lava laid down on top of it. When the poles switch again, the one we call north will move to the south. South will be north. As that happens, the magnetic swaddling that protects our planet will waste away to only about a tenth of its usual vigor. In turn, that will affect each of us and the very fabric of our civilization. As a side note, the auroras, normally seen only in higher latitudes, will likely be visible closer to the equator as solar wind tears more brutally through our atmosphere. When that happens, it will prophesy calamity.
Our Earth’s magnetic field is being made even now in the core. In its turn, the Earth is continually being buffeted by the magnetic field the sun generates within itself, which is within the one our galaxy makes. Most of the planets in our solar system make their own magnetic fields. And they are all related to the universe’s electromagnetic field, one of the fields of fluid-like substances that flow everywhere. The fields can show up in specific places as particles, such as electrons and quarks, which in turn make atoms. As I was trying to understand all this, I spoke with the American theoretical physicist Sean Carroll from Caltech. Theoretical physicists are the poets of science, the ones who can see into the tiny guts of matter and imagine what happened to create the stuff of the universe. At what point in the birth of the universe did the fields and particles show up? I asked him. Fields and particles didn’t show up, he replied. They were always there. Fields are what the universe is made of.
For example, when you try to push the north end of a bar magnet toward the south end of another bar magnet, they snap together. But try to put two norths together and it won’t work, no matter how hard you push. It looks for all the world as if nothing is between the two magnets. But in fact that space is filled with the universe’s immensely powerful electromagnetic force. It is there whether our planet is making its own magnetic field or not. When you play with magnets, you are playing with the universe.
The research for this book has also taken me more deeply into the world of chemistry. One entrée was through my son, Nick Michel, who is studying to be an organic chemist at the University of Toronto. He has patiently sat with me to explain how chemists understand the inner logic of atoms and molecules. I, a Latin scholar, have found myself reading the textbooks of chemistry, physics, and biology. My hunger to understand the planet’s vast magnetic system has prompted me to travel to universities in several parts of Europe and North America, seeking explanations among some of the world’s top scientists. They are the particle physicists who look into the bits that make up atoms and also the astrophysicists whose professional sphere is the machinery of other planets and the stars, including our own sun. They are the geophysicists who yearn to understand how our planet functions and how it once did, and who want to foretell our future. Many of them seemed to be as much at home hacking a piece of rock out of the Earth’s crust as crunching complex numerical simulations through supercomputers.
They have pointed me back in time to the early metaphysicists, to the era when science, magic, and religion were the same thing. For much of
the time humans have been investigating magnetism, it was a dangerous enterprise that threatened the theological ideas that dominated society. The very name of this book, The Spinning Magnet, would have been considered heretical at other points in history because it is a different way of describing the Earth from what the Bible says.
Modern scientists have helped me understand the magnetic investigations of the Middle Ages, the electrical exploits of the Renaissance, and the compulsions of the Victorians. Each of these generations of magnetic explorers had its own philosophies and developed novel explanations for what they found. Each tried to explain their findings in words, often in metaphors, sometimes inventing them for that purpose. To describe a magnet’s poles, for example, is to invoke the metaphor of a planet spinning on its axis in the sky. It is the language of early astronomy, yet it persists today. Other concepts are explained in the language of watchmaking—clockwise and counterclockwise. Or direction—up and down. Or classical physics via astronomy—orbit and spin. It’s a bit of a jumble. And the fact is that even today’s primary way of describing the world in the language of quantum physics—orbitals and fields and superpositions—has not caught up with the ideas it is trying to explain, as Carroll points out.
What that means is that the understanding as well as the language is evolving over time, and will continue to evolve. It also means that the language of one branch of science—say, chemistry—does not necessarily speak the language of another—say, theoretical physics. What you are about to read is a translation of some of these ideas from science into journalism. I hope it throws its own kind of light.
PART I
magnet
I really can’t do a good job, any job, explaining magnetic force in terms of something else that you’re more familiar with because I don’t understand it in terms of anything else that you’re more familiar with.
—Richard Feynman, Nobel laureate, 1983
CHAPTER 1
the beginnings of things
The Spinning Magnet Page 1
