It was almost time for the demonstration to begin. Birkeland was an expert showman. Although his job at the university was supposed to involve teaching as well as research, he rarely had time to spare these days for lecturing and he had taken to paying someone else to do it for him. But on the early occasions that he did grace the lecture hall the students had always loved it, largely because they were never sure what would happen next. His assistant, Olaf Devik, attended many of Birkeland's early lectures and recalled them vividly: "He operated scarce electrical lecture equipment far beyond its rated capacity and burned out fuses with dignified nonchalance. Then he would stop in a royal manner, untie the ruffles of his ermine jacket and dry his glasses in order to better see his latest miscalculation on the blackboard." Birkeland wasn't above blowing fuses deliberately and for effect. Sometimes, he would reach over and almost caress a switch gently for a moment before suddenly pressing it to create a flash of light that made the audience gasp. Then, with the hint of a smile, he would straighten his ruffles and carry on with the lecture.
But for his electromagnetic cannon, the drama was to be in the silence. This was a device that could hurl a torpedo through the air with all the force of a modern weapon of war, and yet with the grace of a bow and arrow. There would be no explosion, no flash, no recoil; just as in the practice runs, the twenty-pound projectile was to emerge smoothly and silently from the gun's barrel, before heading with unerring precision toward its target.
Apart from the narrow safety corridor that Birkeland had railed off between the gun and its target, every seat in the house was filled. (Arctic explorer and professional daredevil Fridtjof Nansen insisted on sitting inside the safety area, and to Birkeland's exasperation he flatly refused to budge.) Birkeland judged that the time was right to begin. "Ladies and gentlemen," he said, "you may sit at rest. When I turn down the switch handle you will not hear anything but the bang of the projectile hitting the target."
He reached for the handle. As he turned it downward, a deafening roar filled the hall. The flash was blinding; a flame tore out of the gun's barrel. The gun had short-circuited, sending a full ten thousand amps of current arcing across the metal casing. Poor Nansen's reaction, sitting as close as he was to the cannon, is sadly not recorded, but the rest of the audience panicked. There were screams of terror, followed by an undignified scramble of dignitaries struggling to escape the crowded hall. "It was the most dramatic moment in my life," Birkeland said later. "With a single shot I dropped my shares' exchange from 300 down to zero." Unnoticed by the fleeing audience, the projectile did indeed hit the bull's-eye, with a thud.
The next day, all of Kristiania was talking about the Festival Hall fiasco. Many of Birkeland's colleagues delicately avoided him. Some even gloated among themselves—it was about time this cocky young man was brought down a peg or two. A lesser man would have been dismayed, but Birkeland couldn't help but find the situation funny. After all, if you have to go down, it might as well be in flames. The question was, what to do next? The short-circuit itself would be simple to fix, but the sensibilities of his potential investors might be a bit harder to patch up.
And then, before he could even make the attempt, he discovered a different use for his accidental spark. A week after his demonstration, at a dinner party hosted by Knudsen, Birkeland met industrialist Sam Eyde, who told him about nitrogen fertilizer. All plants need nitrogen, but if you want to grow them intensively you have to supply the stuff yourself. At the time, the only way to do this was to find natural deposits of saltpeter, a mineral-containing nitrate.
Whoever could artificially produce large-scale quantities of nitrogen fertilizer could revolutionize agriculture and potentially feed the world. Better still, there was a fantastic source of nitrogen just begging to be tapped, and as free as the air. Nitrogen makes up 80 percent of our atmosphere; it is the great diluter, the inert gas that stops oxygen from burning up the world. But the trouble for Eyde lay in its very inertness. In the air, nitrogen exists as a molecule, its two atoms so tightly joined that almost nothing can separate them. From an agricultural point of view, as long as it stays trapped in this form, it is useless.
Eyde had the power to rip nitrogen molecules in two—he owned several of Norway's mighty waterfalls, which, via a hydroelectric plant, could create all the electricity he desired. But he had no idea how to turn his electricity into the sort of rapid, violent spark that he needed.
Birkeland, however, knew exactly what to do. He had terrified half of Kristiania with just such a spark. At the dinner party, he lit up with enthusiasm as he explained his idea to Eyde. With his mighty sparks and Eyde's power source, the two of them could pluck fertilizer directly from the air.
Birkeland put his aurora research on hold. For the next three years he threw himself into the problem of turning his accidental short-circuit into a fully functional furnace for splitting nitrogen. It was a brilliant success, and brought an enormous amount of attention from around the world. Cartoons showed Birkeland, in immaculate suit, bow tie, glasses, and curling mustache, solemnly turning a mangle that wrung dung from the sky, while bystanders held handkerchiefs to their noses and complained of the smell. The money soon began pouring in. Now he could get back to his auroras, and spend it.
***
JANUARY 12, 1570
BOHEMIA
First, a black cloud like a great mountain appeared where several stars had been shining. Above the cloud there was a bright strip of light as of burning sulfur and in the shape of a ship. From this arose many burning torches, almost like candles, and between these, two great pillars, one to the east and one to the north. Fire coursed down the pillars like drops of blood, and the town was illuminated as if it were on fire. The watchmen sounded the alarm and woke the inhabitants so they could witness this miraculous sign from God. All were dismayed and said that never within the memory of man had they seen or heard tell of such a sinister sight.
Nobody who has seen an aurora will ever forget it. The light appears out of nowhere, usually a pale green color, in shimmering curtains or jagged rays, or spirals that curl across the sky like the tracings of a giant snail shell. One of the eeriest things about auroras is that they are soundless. When you see them, you feel that lights like these in the sky should be accompanied by bangs; think of lightning, fireworks, or bombs. But these lights are utterly silent, pulsing in and out of existence like the noiseless kneading of a cat's paws.
Throughout the centuries since the lights were first recorded, they have inspired fear and awe in almost equal measure. Normally, they appear only in the far north or south, dancing over the polar snows during the long winter darkness. When the lights are at their brightest you can read by them, or make out faces inside an otherwise dark hut. They cast shadows. They light your way while hunting. Some say they were created by God for the people of the polar regions, as compensation for the annual loss of sunlight.
Legends abound. The lights flash from the swords of heavenly warriors, the shields of Valkyries, or the flailing wings of swans trapped in the ice. They are dead old maids, dancing and waving white mittens. (This is from western Norway, and a version of it persists today; it is still sometimes said of elderly spinsters that they will soon be off to the northern lights.) Some believe that waving a white cloth will make the lights stronger; others that waving or whistling at them will bring their wrath down upon you.
Many find them menacing. The lights will tear out your hair if you walk beneath them unveiled; they will take your children's heads and use them as balls to kick around the sky. They are a terrible portent, harbingers of war, poverty, and plague.
This last fear arose most often when the lights escaped their usual bounds and made a rare foray to more southerly latitudes, where the people were unused to their flickering. Away from the poles, the white and green is often tinged with a violent red, as it was in the scene that terrified sixteenth-century Bohemia. These fears persisted even long after the superstitious Middle Ages had given way to
more enlightened times. On September 9, 1898, red and orange auroral lights appeared without warning over the skies of London, Paris, Vienna, and Rome, leading many to fear imminent disaster. The next morning, this portent seemed to have been confirmed, when news broke that the beautiful and well-loved Empress of Austria had been stabbed to death by an Italian anarchist.
Birkeland, of course, had no patience with such superstition. He sent an immediate telegram to an astronomer he knew, asking what was happening to sunspots around the same time. Soon, he received the answer he had been expecting. Just a few days before the auroral display, several unusually large groups of sunspots had appeared and lingered on the solar face.
Since Galileo had first peered through his telescope in the seventeenth century, the sun was known to bear the occasional unsightly speckle on its surface. (Identifying them was one of Galileo's stated crimes against the Church, for how could God's almighty creation be imperfect?) And by Birkeland's time it was beginning to be clear that the sun was prone to outbursts that might be related to these spots. On September 1, 1859, British scientist Sir Richard Carrington of the Kew Observatory became the first human to see such a flare-up in action. He was in the process of making one of his regular observations of sunspots. Since regarding the sun directly was now known to be dangerous to eyesight, something that Galileo learned only too late, Carrington was prudently projecting the sun's disk onto a plate of glass coated with distemper of a pale straw color. Nonetheless, the image was quite detailed, being some eleven inches across. He was carefully noting the positions of the spots when, from a group clustered toward the sun's northern latitudes, there came two patches of intense white light.
At first Carrington thought there must be a hole somewhere in his apparatus, but he quickly realized he was witnessing something much more important. "I therefore noted down the time by the chronometer, and seeing the outburst to be very rapidly on the increase, and being somewhat flurried by the surprise, I hastily ran to call someone to witness the exhibition with me, and on returning within 60 seconds, was mortified to find that it was already much changed and enfeebled." Carrington calculated that in the space of five minutes, the two light patches had traveled some 35,000 miles.
The effect of this flare was soon to be felt on Earth. Eighteen hours after Carrington's observation, a magnetic storm disrupted telegraphs around the world, and auroras were seen far outside their usual bounds, in Hawaii, Chile, Jamaica, and Australia. This made perfect sense. Explorers had already noted that auroras seemed to make compass needles swing unexpectedly. Indeed back in the eighteenth century, a Swedish scientist named Olaf Peter Hiorter had spent an entire year recording the position of a compass needle every hour to see how it deviated when the northern lights flickered overhead. He did take the time off for two short trips home, in August and at Christmas, but he still took an impressive—one might say excessive—6,638 readings.
Hiorter had intended his research as a warning to travelers in the northern lands that they should not trust their compasses when the auroras came. But Birkeland saw in it a deeper significance. If he was right, and the auroras were caused by electrons streaming in from the sun, then Earth's magnetic field would naturally be affected. As Birkeland knew well from his work in the entangled world of electromagnetism, where there were moving electrons, there was electricity; and where there was electricity there would be fluctuations in magnetism.
Moreover, those changes would be strongest around the poles. The magnetic field that surrounds our planet looks a little like an apple cut in half: Its lines of force emerge from the South Pole, bend over the equator, and disappear back into the North Pole. Such "closed" field lines form an almost impenetrable magnetic barrier, and few electrically charged particles from space can cross their invisible force field. However, the lines emerging most steeply from the South Pole do not connect with their counterparts in the North. Instead, both poles have a smattering of field lines that point directly up into space. These, Birkeland believed, provided the opening his cathode rays needed. The cathode rays would spiral down the open-ended field lines like beads on a chain until they hit the atmosphere. On the way, they would set the magnetic field jangling, and when they arrived they would be soaked up by the air, making it glow with the ghostly flickers of the auroras. The northern and southern lights were simply the outward signs of our sentinel atmosphere at work.
Thus, on September 16, Birkeland published an article in Verdens Gang, a Norwegian newspaper, entitled "Sunspots and auroras: a message from the Sun." The auroras that had given rise to such fear across Europe were not some ghostly portents of disaster, he wrote. They were the outward signs of something streaming toward us from our own parent star.
Birkeland knew he had a great theory, but he still needed to prove it. With the money coming in from his inventions, he decided to build the biggest, most sophisticated lab that the university had ever seen. Before long, the room was so crammed with equipment that only people working on the experiments were allowed to enter; students had to bellow their questions from the door. Electrical cables were draped everywhere; a massive power generator occupied a full third of the room, along with banks of rechargeable batteries, cameras, and hand tools. Birkeland became famous for the bangs, the flashes, and the odd smells that emanated from his new kingdom. A university committee was supposed to inspect every room at least once a year, but this was one lab they never dared to go near.
Even for Birkeland and his team, the lab had its dangers. They had all become used to receiving the occasional electric shock, and had taken to working with one hand in their pockets so that any large shock would travel straight down their sides and not across their hearts.
In the lab, Birkeland had grown more eccentric in his dress. He still sported his smart suits and immaculate cravats, but he now often completed the ensemble with an Egyptian fez made of felt and matching slippers in red leather with long, pointed toes. To the credulous, he claimed the fez was to protect his head from harmful electromagnetic radiation. To others he confided that it kept his bald head warm.
He worked obsessively. One of the first words that anyone describing Birkeland used was "tireless." He had had chronic insomnia since childhood, and his solution was often to continue working through the night. When a project had gripped him he would stop for nothing, not even to eat. One of his assistants wrote about him: "I never knew another man so engaged with science and with such reckless devotion. He worked far beyond the resources a human constitution can tolerate. It never occurred to him not to concentrate wholly on work." (This same attitude had cost him his marriage. During his work on the furnaces, Birkeland had married a teacher four years his senior, but she was unable to tolerate his work habits and left him not long afterward. Birkeland wasn't overly concerned when she left—just anxious to make sure that everyone knew it was his fault, and that she had plenty of money. He might have overdone it, since though she neither remarried nor took another job, she spent the rest of her summers sunning herself on the French Riviera.)
And yet for all his intense focus, Birkeland could be maddeningly abstracted. Sometimes in the lab he became unexpectedly distant; he would leave his assistants working and wander out into town for an hour or two without explanation. When he returned, his hat would be pushed to the back of his head, and he would burst in full of excitement about some new idea or insight.
Birkeland also had a fundamental disdain for bureaucracy. He kept neither diary nor notebooks, but simply scribbled notes on scraps of paper that he stuffed in his pocket or lost under cushions or left to float around the lab. Though he fortunately had an excellent memory, he still must have tried the university administrators beyond endurance. When asked to document the details of his expenses, he replied, "What for? I remember the sum." He would send the officials small notes declaring that he had taken over this or that room for a new laboratory. Once he even appropriated half a lecture hall. "By putting the students closer together there is enough space in the
reduced hall" was the casual way he informed the infuriated dean and vice-chancellor. He assuaged their fury by paying for all the alterations himself.
The most impressive thing about Birkeland's new lab was the vacuum chamber that held his artificial sun and earth. It was a full cubic meter in volume, its sides straight like those of a glass aquarium but with curved corners and walls two inches thick to prevent it from collapsing when the air was sucked out. Indeed the chamber was big enough for his most slender assistant to climb inside and sit cross-legged to clean the walls. (Birkeland once teased him by "accidentally" trapping him inside. He loved practical jokes, and his assistants tolerated them good-humoredly. Once he set up an iron bar so it was highly magnetized, laid it on a metal table, and then nonchalantly asked one of his assistants to move it. After the assistant had struggled for a few moments, the others joined in and by heaving together managed to shift the bar an inch or so. They were so involved in their task that nobody noticed Birkeland as he flicked off the switch that was powering the magnet, and bar, assistants, and all went flying off the table.)
Inside the chamber, near one of the walls, a glowing cathode generated beams of electrons to imitate the sun. The rays then barreled invisibly through space until they encountered Birkeland's terrella, which is Latin for "little earth." This was a thin brass sphere, about fourteen inches across, inside of which was an electromagnet made up of an iron core wound about with copper wire. For extra authenticity, Birkeland had even ensured that the magnet was tilted by 23.5 degrees, so it would match Earth's own tilt.
The surface of the sphere was coated with barium platinocide, a chemical that glows when hit by electrons, just as television screens do today. When Birkeland ramped up the terrella's internal magnet, electrons from the cathode "sun" would veer off toward the terrella's poles, where they would dance in two rings, one north and one south, with a ghostly purple glow.
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