The Northern Lights, page 4
On the last day of October Hætta arrived, two days before his usual weekly delivery, with a letter from Hammerfest. It was dictated by Hansen who was convalescing in a hospital after an operation to remove the tips of all his fingers, some to the first joint, others to the second. He planned to return to Christiania as soon as he was well again and wished them all good luck. The men fell silent at the thought of Hansen’s suffering and the loss of his future career. That the mountain had claimed a victim so soon shocked Birkeland, who hoped that his small group would survive the Arctic winter with no more casualties.
3
The Castle
November 1899
Auroral observatory, Haldde Mountain
As I looked, behold, a stormy wind came out of the North and a great cloud with brightness round about it, and fire flashing forth continuously and in the midst of the fire, as it were gleaming bronze like the appearance of the bow that is in the cloud on the day of rain, so was the appearance of the brightness round about.
The Book of Ezekiel in the Old Testament, c. 593 B.C.
LIFE IN “The Castle,” as the observatory had been christened due to its resemblance to the mythical abodes of troll giants, began smoothly. From 1 November, when observations began in earnest, Sæland’s timetable became the group’s bible, giving structure to their days and guidance on the freezing nights when they followed the schedule like sleepwalkers, too cold to think for themselves. One man would do the morning measurements, another the afternoon’s and another the night’s. Sæland, alone on Talvik peak, took all the meteorological and auroral measurements himself.
The tour of duty at the main observatory began by winding up the automatic recording devices in the instrument room, changing the photographic paper, and developing the exposed rolls. It had taken several days for Birkeland to trust Boye and Knudsen to fulfill this task without disturbing the magnetometers. Next, layers of reindeer skins, hoods, mittens, and boots were donned in order to record wind speeds, air humidity, temperature, and air electricity, and to note in ledgers any auroral activity, weather formations, and particular cloud shapes during Northern Lights displays. They did not see auroras every night; in fact, they appeared infrequently and a whole week could pass without a sighting. Sometimes cloud cover hid the sky; sometimes the moon was so bright the Lights were hard to discern against it; sometimes the night was as clear as a new window but only the stars could be seen. On nights when auroras blazed across the heavens, the man on duty would wake up his colleagues, phone Sæland, and carry the photographic equipment outside. Glass plates were inserted into the back of the camera and a view of the Lights fixed in relation to the stars in the sky. The position was then relayed to Sæland, who arranged his own camera. At a certain signal the operators of both cameras would open their shutters, usually for ten seconds or more. The plates were then stored in the darkroom to be developed the following day. As the men curled into their bunks at night, it was not the biting cold that made it difficult to sleep but the excitement of seeing the auroras and hoping that soon they would have scientific explanations that were every bit as dramatic as the old Norse fairy tales.
Birkeland usually offered to do the night-time readings. He had been plagued with insomnia since his student days and remembered lying in bed as a child listening to the city fall silent. Now he used his sleeplessness as an opportunity to work through the night. He would putter around the instrument room making tiny adjustments or watching for movements in the mirror of the magnetometer as each minute twist showed that out in space the magnetic field was pulsating. When the instrument moved more strongly he would pull on his reindeer skins to see if the aurora had appeared. If the weather was clear, the sky would be filled with mysterious, luminescent streamers more brilliant than any fireworks or electric lights.
Although Birkeland regularly sat in temperatures of −20° Celsius to watch the light displays, he was oblivious to the cold. He agreed with folklore that the lower the temperature, the brighter the Lights, although he could find no explanation for this. Their arrival, heralded by rapid movement in the magnetometers, was perfectly silent as the first sinuous streak of light appeared above the distant mountain peaks and arced slowly across the sky, from horizon to horizon. They would sometimes form translucent curtains, blowing like gauze across the darkness. Birkeland was increasingly convinced that they must appear above the height where any wind could catch them, and he certainly did not witness them touch the ground.
He would lie flat on the roof of the tower and gaze at the shooting lines of light wrapping their brilliance around the crown of the Earth, like a ribbon shot through with iridescent metals, tracing distant mountain peaks and valley troughs, filling the night with shimmering threads. From his vantage point, Birkeland could see for about one thousand kilometers from horizon to horizon, but he knew that the Lights continued beyond his line of sight to create a dazzling crown around the magnetic pole of the Earth. These “auroral glories,” as they were christened due to their similarity to haloes, were first surmised in the middle of the eighteenth century, when a Swedish professor, traveling around North America to collect seeds and plants, also noted the dates and positions of auroral displays. When he returned to Sweden this information was correlated with local observations of the Lights and it became clear that the same display had been seen. In the years following this discovery, other observations of the Lights across the globe proved that they occurred in an oval around, but rarely over, the pole. Captain Cook had witnessed that the Lights also occurred around the South Pole in 1770 during the voyage of the Endeavour. He christened them the “aurora australis.” As Birkeland watched the Lights, night after night, he realized that if his theory was correct the Lights seen around the two poles would be a mirror image of each other. He did not have proof for this, but his intuition told him it must be true.
The weather proved the little group’s main challenge as autumn became winter. Birkeland’s notes express disbelief in the violence of the storms:
The wind sometimes roars so against the house that you would have thought you were sitting at the foot of a waterfall; and the floors tremble and everything shakes. We are able to gauge the storm outside by the noise within. Often we cannot get out of the house ourselves for several days and it takes three strong men to shut our little door. One strong anemometer was blown apart in the course of a few days and we found pieces of it 50 to 100 metres from the place it had been put up.
The telephone cable was as vulnerable as the instruments on the observatory roof. In nine or ten hours of bad weather the cable could become as thick as a man’s arm with ice and frequently snapped under the weight. Knudsen and Boye would set out with ladders and rubberized sheathing as soon as the winds died down.
We have seen a layer of snow a metre thick and so hard you could jump on it without sinking in, practically disappear from the summit in the course of a few hours. It may be imagined what a whirling and drifting there is in the wind, when the snow is comparatively fresh and not pressed into a compact mass. Even indoors the situation is not always comfortable. Water freezes a couple of feet from the stove and the lamp is often blown out on the table in the middle of the room, although in a general sense the house is well-enough built.
It was hard to tell when one day ended and the next began, and the logbooks were marked “a.m.” and “p.m.” to prevent confusion. Long days of work were punctuated by brief moments of excitement—when the aurora twisted over the distant mountains, or on the occasional mornings when Hætta appeared with the post or Sæland arrived with his measurements and to pick up supplies. The days were busy with taking recordings, mending the instruments outside, keeping warm, and reading. Despite the intense cold, the little sunlight, and the monotonous diet of meat, there was rarely any tension in the observatory. Boye, in particular, used the time for almost constant questioning of Birkeland, trying to cram the contents of a science degree into a crash course of a few months. The professor was a patient and inspiring teacher, grabbing any available object or drawing simple diagrams to make abstract concepts visible. Although he admired all the men on his team, it was the irrepressible Boye to whom he became most attached. When not on duty, the two would often sit around the stove, discussing basic concepts such as gravity and electricity, Boye benefiting from the most contemporary and profound understanding available in Norway and Birkeland enjoying the intelligent and often surprising questions Boye asked. For Birkeland, the expedition had an unexpected and pleasant side effect: he felt happy. He enjoyed being surrounded by intelligent young graduates whose enthusiasm and energy matched his own, their banter and practical jokes alleviating the bone-aching cold. Far from being depressed by the weather and diminishing daylight, Birkeland was enjoying the challenge that the location and the scientific puzzle presented and the camaraderie that resulted among the closely knit team.
There had been several times in Birkeland’s life when he had not been so contented—he had blamed these episodes of “nervous freezing fits,” when he lay incapacitated in bed, on overwork, physical illness, or homesickness if they occurred while he was traveling, but the truth was that he had suffered from mild mania and depression since his student days.
3, rue Casimir Delarique
Paris
5.2.1893
Dear Bjerkenes!
Thanks for your letter; you can’t imagine how timely it was. I have been in bed for four days without sleeping after a tremendous nervous freezing attack caused by too much work. Now I am up again and feel relatively well but I think it is necessary to proceed more carefully.
Now about the Carnival fun. Yesterday was the first day I could think of going out after my illness and I decided to watch the parades and spectacles in the grands boulevards . . . as you know, confetti plays a large part in these and I bought a large bag for fifty centimes to return fire from sweet young ladies! . . .
Best wishes to you
Kristian
His prodigious talent had a cost in that it was fueled by an appetite for work that his body could barely cope with; he became lost in the puzzles he found and time ceased to exist, tiredness and hunger evaporated. Newton had once replied, when asked how he managed to conceive of gravity, “by thinking continuously upon it”; Birkeland did the same, driven to explore the ideas that arose in his mind. His acute scientific intuition was born of a young life devoted entirely to “thinking continuously upon it.” Here on the mountaintop Birkeland was free to spend every minute on his work: there were no other demands upon his time and the act of living, though strenuous due to the conditions, was simple.
On most days Birkeland would spend several hours with the magnetometers. Before entering the room he emptied his pockets of pens, penknife, keys, and any other object that might contain magnetic materials that would disrupt his results. All the buttons on his clothes had already been replaced with bone, his glasses were rimmed with gold, a nonmagnetic metal, and he wore reindeer slippers that enabled him to tread softly among the instruments. His three magnetometers were in constant use, writing a map of the magnetic field for every second of the day. The first showed the direction of the field, the second its horizontal strength, and the third its vertical strength, from which calculations could be made to map its position overhead and note any changes that occurred. They had been made in Germany by the best instrument manufacturer in Europe, Otto Toepfer, and were about the size of large shoeboxes. In one side of each instrument a hole was pierced, six centimeters in diameter, through which a quartz thread could be seen hanging, like the workings of a grandfather clock. Attached to the bottom of the thread was a tiny magnet that sensed changes in the magnetic field caused by electric currents flowing overhead at least a hundred kilometers above the Earth’s surface, possibly as far as 100,000 kilometers away. A continuous recording was made automatically using a narrow beam of light from an oil lamp, focused with the use of a lens, beamed directly at a small mirror attached to the front of the magnet. This tiny mirror reflected the beam onto a long roll of photographic paper that scrolled by clockwork at a steady pace. As long as Birkeland remembered to wind up the recording machine every day and refill the oil in the lamps, the beam of light would create a continuous line on the photographic paper that fluctuated as the magnet responded to changes in the magnetic field. If there was no magnetic activity, a straight line would be produced. The scrolls would be developed every morning in the darkroom and hung up to dry. By comparing them with visual observations of auroral activity, Birkeland would soon build up an accurate picture of how movements in the magnetic field related to the occurrence of auroras.
Birkeland first became fascinated by the force of magnetism at school when his math teacher, Elling Holst, had persuaded him to buy a magnet with the money Birkeland made from teaching math to his less talented peers. Rapidly he learned what his magnet could do by experimenting with it and reading all he could about magnetism. He became fascinated by the Englishman William Gilbert, who in 1600 wrote a book called De Magnete (On a Magnet). Not only was it the first major scientific book published in England, but in it Gilbert established that “the Earth itself is a giant magnet.” In Gilbert’s time bar magnets, such as Birkeland bought as a child, did not exist. The only naturally occurring magnetic materials were iron and “magnetite” or “lodestone,” a rare rock that had magnetic properties and was quarried, with iron, along the coasts of the Aegean Sea, on the Mediterranean islands, and near Magnesia in Asia Minor, whence the name derived. An ancient Greek fable explained the name: a shepherd, Magnus, was walking on Mount Ida in Crete when the tacks in his sandals and the iron tip of his staff became so strongly attracted to Earth that he could not move. He began digging to ascertain the cause and found a wonderful stone— which he called after himself, magnetite. As it was not possible to dig into the core of the Earth, the mechanism that created the magnetic field was still one of the greatest unsolved scientific mysteries of Birkeland’s day, along with the Northern Lights and what powered the sun.
For his experiments, Gilbert made spheres of lodestone turned on a lathe, a difficult task in itself due to the hardness of the material, and called them “terrellas,” little Earths. Placing iron needles that could pivot freely around the terrella, he noticed that the needles all pointed north. When he put terrellas on cork floats and let them move freely in water, he saw that they circled each other for a while before coming together—for the north pole of a magnet is only attracted to the south pole of another magnet and vice versa. Gilbert discovered not only that the Earth was a magnet, but also that it had two poles, north and south. When iron filings were sprinkled around a magnet, they spread out furthest at the poles, forming a shape like an apple cut in half with the magnet, or the Earth, being the central pip. The strength of the field was at its greatest at the poles because the lines of force were more concentrated there. As Birkeland and scientists before him had understood, the auroras were mostly seen in the polar regions of the Earth—where the lines of magnetic force could reach great distances into space. Birkeland also saw, from studying the magnetometer readings, that the auroras appeared only when the steady magnetic field was disturbed and “storms” could be detected. What force was creating these storms was the question Birkeland sought to answer.
Gilbert had realized that magnetism was a force related to but separate from electricity, he was the first to use the words “electricity,” “electric attraction,” and “electric force.” He took the terms from Thales of Miletus, who, in the sixth century B.C. in ancient Greece, noticed that rubbing amber gave it the power to attract light objects. This phenomenon, later known to be static electricity and produced by many materials when rubbed, was named after the Greek word for amber, “electron,” the root of the terms Gilbert coined.
It took more than two hundred years from the publication of De Magnete for the connection between magnetism and electricity to become clear. In 1820, the Danish natural philosopher Hans Christian Ørsted set up an electric circuit and held a compass near the wire. When the current was flowing, the needle of the compass was deflected. Ørsted realized that the electric current caused this magnetic disturbance and that an electric current must therefore have magnetic effects. Eleven years later, Michael Faraday, a research assistant at the Royal Institution in London, demonstrated that when a copper wire was subjected to a changing magnetic field— the opposite of Ørsted’s experiment—an electric current began to flow through the circuit. Magnetic forces, he observed, gave rise to electric currents—a discovery he called “electromagnetic induction.” This discovery led to the invention of dynamos and generators that in turn led to electric lights, the telegraph, the telephone, and other technological developments that Birkeland had witnessed changing the world around him during his youth. Faraday realized that light must also be a form of electromagnetism, an idea later proved by James Clerk Maxwell, a Scot, in his Treatise on Electricity and Magnetism (1873). Maxwell tied together the work of Ørsted, Faraday, and other experimenters in a series of equations that contained the fundamental laws of electromagnetism: that an electric current was always accompanied by a magnetic field and that a varying magnetic field created an electric field. The equations also stated that a varying electric field gave rise to a magnetic field and thus the two kinds of fields could create each other in an endless loop. The result was a wave of electric and magnetic fields inextricably tied together and emanating outward in space. Maxwell called them “electromagnetic waves” and proposed that waves with a length of about a thousandth of a millimeter corresponded to visible light, but he also showed that waves with much greater or shorter lengths were possible. This was proved experimentally in 1888 by Heinrich Hertz, who generated radio waves, and in 1895 by Wilhelm Roentgen, who discovered X-rays. Birkeland himself had used Maxwell’s equations to study mathematically the propagation of such waves under certain conditions and was the first to do so successfully—a feat that had propelled him into the first rank of mathematical theoreticians at the age of twenty-eight. Now he intended to use this knowledge to unravel the complicated physics behind the aurora.
