An Ocean of Air (32 page)

The technology behind the gun was close to Birkeland's heart. He was fascinated by the burgeoning new science of electromagnetism. Earlier in his career he had studied in Paris with Henri Poincaré, one of the world's most famous scientists. And there, he had come across a set of extraordinary equations.

These were the same equations that had inspired Heinrich Hertz, and were even now electrifying Oliver Heaviside over in his rural English retreat. Back in 1873, when Birkeland was only six years old, Scottish scientist James Clerk Maxwell had produced a set of fundamental laws for how electricity and magnetism were entangled. He had put together all the discoveries about these two forces that had been trickling out over the previous decades. Electricity, it seemed, somehow affected magnets: If you hold a compass near a wire that is conducting electricity, the compass needle
will lurch. The opposite also holds true: Take a simple piece of copper wire and move it past a magnet and an electric current will immediately begin to flow through the wire, even when there's no battery or power source in sight. Electric fields somehow beget magnetic ones and vice versa, and this is what Maxwell's equations had captured.

The relationships embedded in Maxwell's equations also meant that electric and magnetic fields could reproduce each other in endless serpentine waves. That's what electromagnetic waves like light and radio waves were made of, all simply squeezed or stretched variants of the same interweaving fields.

As well as advances in physics, the equations presaged plenty of inventions: Marconi's telegraph, Bell's telephone, and also electric dynamos and motors. Because another aspect of Maxwell's equations showed that if you put a conducting object in a magnetic field, the object would move.

That's what had given Birkeland the idea for his cannon. What if, instead of using gunpowder, you could blast projectiles through the air with the power of electromagnetism? Surely that would be worth a fortune.

The money was what he was really after. Though Birkeland was entertained by his technological tinkerings, he was engaging in them to fund his true but expensive passion. He had become riveted by the question of what causes the northern lights.

Back in the 1890s, when he had begun his university research, Birkeland had been investigating a recently discovered phenomenon: cathode rays. These were invisible rays that streamed from a hot cathode into a vacuum, announcing their presence only when they hit the glass wall of the chamber, which had been coated with fluorescent paint and would glow a ghostly purple or green. (This is exactly the same principle used in televisions, before the flat-screen revolution. The normal bulky box of the "tube" contains a hot cathode, which pours invisible rays through an evacuated chamber to paint an image when they hit the inside of the screen.)

When Birkeland started working on cathode rays, neither he nor anyone else knew exactly what they were. Like many of Maxwell and Hertz's electromagnetic waves, cathode rays were invisible and energetic. But in one crucial respect they were very different. Put a magnet near x-rays, or light, or wireless waves, and nothing happens. Their own inbuilt magnetic fields swamp anything the magnet can do, and the waves plough on undisturbed.

But cathode rays are different. When Birkeland put one of his magnets anywhere near them, the cathode rays slewed around and headed for the magnet's poles. This gave him an idea. He coated a magnetic object with fluorescent paint and sent a beam of cathode rays heading straight for it. As he had anticipated, the invisible rays suddenly appeared, dancing in glowing sheets of light over the magnet's north and south poles. They looked a bit like the aurora borealis, the "northern lights."

The phenomenon of sheets of ghostly green, red, and white curtains billowing over the poles had been known for centuries, and attempts at explaining these lights were as bizarre as they were numerous. But staring at his glowing magnet in the vacuum chamber of his lab, Birkeland became convinced that the truth was, if anything, even stranger. The sun was hurling beams of cathode rays in our direction. Earth's own magnetic field then captured these beams and directed them to the poles, where the air soaked them up and glowed with their energy.

A year after Birkeland came up with this idea, in 1897, British scientist J. J. Thomson discovered something else important about cathode rays. They weren't rays at all, or at least not steadily moving waves. Instead they were streams of tiny negatively charged particles—what we now know as electrons.

This would turn out to be most significant. Because if Birkeland was right, the sun was flinging electrons and perhaps other positively charged particles toward Earth. These charged particles are a form of something we have learned to fear: the menacing radiation also created in a nuclear explosion. Though he didn't know it, Birkeland's suggestion was about much more than what creates the auroras. His hunch would lead to the discovery of exactly how our atmosphere protects us from the radioactivity that fills the rest of space.

Immediately, Birkeland had decided to set about trying to prove his hunch. However, what he had in mind would be very expensive: polar expeditions, new auroral stations, measurements, and a laboratory the likes
of which King Frederik University had never seen. Even though Birkeland was already receiving a large share of the university's research budget, he would need much, much more. So he decided to turn to his own inventiveness to supply the missing funds.

Birkeland enjoyed inventing things almost as much as he enjoyed figuring out physics. By the end of his life he would hold more than sixty patents for items as diverse as electric blankets, mechanical hearing aids, and a technique for hardening whale oil to make solid margarine. But of all Birkeland's inventions, he had the highest hopes for his electromagnetic cannon. Also in the Festival Hall was a certain Mr. Gunnar Knudsen, an engineer and member of Parliament who was one of the five partners in the Birkeland Firearms Company. Birkeland had written to Knudsen two years earlier, inviting him to join the company he was forming:

I have just recently invented a device with which it seems possible to use electricity instead of gunpowder as a propellant ... Colonel Krag, who has witnessed my experiments, has proposed that a company be formed, consisting of a few men who will furnish capital to build a small gun according to my plans ... Naturally, it would mean playing a lottery, but the contribution would be comparatively small, while I believe the chances are good for significant gains.

Knudsen knew and liked Birkeland, and had already supported some of his basic research. He replied good-naturedly: "I accept with pleasure your invitation to participate in your invention, and promise, even if the big lottery does not appear, to keep smiling." Under the circumstances, that was to be just as well.

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.