KRISTIAN BIRKELAND
ASTROPHYSICS AND SPACE SCIENCE LIBRARY
VOLUME 325 V
V
EDITORIAL BOARD Chairman
W.B. BURTON, National Astronomy Observatory, Charlottesville, Virginia, U.S.A.
([email protected]); University of Leiden, The Netherlands ([email protected])
Executive Committe
J. M. E. KUIJPERS, Faculty of Science, Nijmegen, The NetherlandsFF
E. P. J. VAN DEN HEUVEL, Astronomical Institute, University of Amsterdam, The Netherlands H. VAN DER LAAN, Astronomical Institute, University of Utrecht, The Netherlands
MEMBERS
I. APPENZELLER, Landessternwarte Heidelberg-K¨onigstuhl, GermanyK¨K J. N. BAHCALL, The Institute for Advanced Study, Princeton, U.S.A.
F. BERTOLA, Universit´a dt´t i Padova, ItalyPP
J. P. CASSINELLI, University of Wisconsin, Madison, U.S.A.
C. J. CESSARSKY, Centre d’Etudes de Saclay, Gif-sur-Yvette Cedex, France O. ENGVOLD, Institute of Theoretical Astrophysics, University of Oslo, Norway
R. MCCRAY, University of Colorado, JILA, Boulder, U.S.A.
P. G. MURDIN, Institute of Astronomy Cambridge, U.K.
F. PACINI, Istituto Astronomia Arcetri, Firenze, Italy V. RADHKRISHNAN, Raman Research Institute, Banglore, India
K. SATO, School of Science, The University of Tokyo, Japan F. H. SHU, University of California, Berkeley, U.S.A.
B. V. SOMOV, Astronomical Institute, Moscow State University, Russia R. A. SUNYAEV, Space Research Institute, Moscow, Russia Y. TANAA AKA,NN Institute of Space & Astronautical Science, Kanagawa, Japan
S. TREMAINE, CITA, Princeton University, U.S.A.
N. O. WEISS, University of Cambridge, U.K.
KRISTIAN BIRKELAND
The First Space Scientist
by ALV EGELAND University of Oslo, Norway
and
WILLIAM J. BURKE Air Force Research Laboratory, USA
A C.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN-10 1-4020-3293-5 (HB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN-10 1-4020-3294-3 (e-book) Springer Dordrecht, Berlin, Heidelberg, New York ISBN-13 978-1-4020-3293-6 (HB) Springer Dordrecht, Berlin, Heidelberg, New York ISBN-13 978-1-4020-3294-3 (e-book) Springer Dordrecht, Berlin, Heidelberg, New York
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Caption to Front Plate: Professor Kristian Birkeland with his left hand resting on an electric discharge tube of the high-voltage device used in 1896 to generate artificial auroral displays in
his laboratory. Asta Nørregaard (1853–1933) painted this portrait in 1906 (100× 83 cm).
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CONTENTS
Preface . . . ix
Introduction . . . 1
Part I: Background and Education . . . . 11
1 At the 19th Century’s End . . . 11
1.1 Union of Norway and Sweden . . . 11
1.2 The Royal Frederik University in Kristiania . . . 12
1.3 Early Investigation of the Aurora and Geomagnetism . . . 13
2 A New Abel . . . 17
2.1 The Birkeland Family . . . 17
2.2 High School and University Education . . . 19
2.3 Postgraduate Research in France, Switzerland, and Germany . . . . 22
Part II: Geomagnetic and Solar System Research . . . . 27
3 Aurora in a Vacuum Chamber . . . 27
3.1 Electromagnetic Wave Experiments . . . 27
3.2 Early Laboratory Simulations . . . 28
3.3 Birkeland’s Offices and Laboratories at the University . . . 34
3.4 Terrella as Anode Experiments . . . 36
4 The Norwegian Auroral Expeditions . . . 45
4.1 Birkeland’s First Expeditions . . . 45
4.2 Arctic Expedition of 1902–1903 . . . 57
4.2.1 The Four Stations . . . 61
4.2.2 Birkeland’s Main Research Contribution . . . 66
4.3 Classification of Geomagnetic Disturbances . . . 70
4.3.1 Polar Elementary Storms . . . 72
4.3.2 Equatorial Perturbations . . . 73
4.3.3 Cyclo-Median Perturbations . . . 74
4.3.4 Field-Aligned Currents in Space . . . 75
4.4 The Permanent Station at Haldde Mountain . . . 77
4.5 Controversies with the British School . . . 80
5 The Universe in a Vacuum Chamber . . . 87
5.1 Terrella as Cathode Experiments . . . 87
5.2 Sunspots and the Solar Magnetic Field . . . 87
5.3 Comet Tails . . . 90
5.4 Saturn’s Rings . . . 93
5.5 Zodiacal Light . . . 94
5.6 Conflicts with Carl Størmer . . . 98
vi CONTENTS
Part III: Technology and Applied Physics . . . . 101
6 Fast Switches and Electromagnetic Cannons . . . 101
7 In as Little as Four Years . . . 109
7.1 Plasma Torch and Nitrogen Fixation . . . 109
7.2 Foundation of Norsk Hydro . . . 115
7.3 Conflict with Sam Eyde . . . 120
7.4 Marcus Wallenberg . . . 123
7.5 Other Technical Applications . . . 125
7.5.1 X-Rays . . . 126
7.5.2 Atomic Energy . . . 126
7.5.3 Rocket Propulsion . . . 128
7.5.4 Radiowave Propagation . . . 128
7.5.5 Production of Margarine . . . 129
7.5.6 Hearing Aid . . . 129
7.5.7 Cod Caviar . . . 130
7.5.8 Radiation Treatment . . . 130
Part IV: Birkeland the Man . . . . 131
8 As Seen in His Own time . . . 131
8.1 Teacher and Experimenter . . . 132
8.2 Birkeland as a Popular Author . . . 135
8.3 Positions and Honors . . . 137
8.4 Nominations for the Nobel Prize . . . 138
8.4.1 Nobel Prize in Chemistry . . . 139
8.4.2 Nobel Prize in Physics . . . 140
9 Consummatus in brevi, explevit tempora multa . . . . 141
9.1 Birkeland’s Health . . . 141
9.2 Marriage and Divorce . . . 143
9.3 Sojourn in Egypt . . . 145
9.4 Death in Tokyo . . . 148
9.5 Many Friends . . . 156
9.6 Birkeland’s Will . . . 162
Part V: Birkeland’s Heritage . . . . 165
10 From Small Acorns . . . 165
10.1 Science Education in Norway . . . 166
10.2 Influence on Solar-Terrestrial Research . . . 167
11 In Memoriam . . . . 175
11.1 Kristian Birkeland Research Fund . . . 175
11.2 Birkeland Symposium . . . 176
CONTENTS vii
11.3 Birkeland Lecture Series . . . 176
11.4 The Norwegian 200 Kroner Banknote . . . 179
Appendix 1 Birkeland’s Scientific Publications . . . 181
Appendix 2 Archives and Unpublished Sources . . . 189
Olaf Devik’s Personal Archive . . . 189
The Birkeland-Eyde Industrial Museum at Notodden . . . 189
Norwegian Technical Museum in Oslo . . . 190
The National Library Archive . . . 191
Norsk Hydro Archive . . . 191
Sam Eyde Archive . . . 191
Norwegian Storting Archives . . . 192
University of Oslo, Central Administration . . . 192
Stockholm Enskilda Banken Archives . . . . 192
Norwegian Academy of Science and Letters Archive . . . 192
Printed Sources from Norwegian Newspapers and Journals . . . 192
Biographies . . . 194
Appendix 3 Patents . . . 195
Appendix 4 Letters . . . 201
Letter: Birkeland to Kaja Geemuyden . . . 201
Extracts from Terada’s Diary Concerning Kristian Birkeland in May–June 1917 . . . 203
Letter: Terada to Birkeland (written in English) . . . 205
Letter: Terada to Birkeland (written in English) . . . 206
Letter: Nagaoka to Birkeland (written in English) . . . 207
Letter: Terada to Birkeland (written in English) . . . 208
Letter: Nagaoka to Birkeland (written in English) . . . 209
Letter: Gerda Thomsen to Karl Devik . . . 210
Letter: Eriksen to Birkeland . . . 213
Bibliography . . . 215
Index . . . 219
PREFACE
This scientific biography of Kristian Birkeland (1867–1917) was written to bring the story of a Norwegian national hero to the attention of the English- speaking world. Birkeland’s heroic stature was established not on a field of military battle, but in the bitter cold of the Artic wilderness as he sought to answer basic questions about how the Sun controlled northern lights and mag- netic storms. He was also a father of Norsk Hydro one of Norway’s largest industries. Birkeland died before reaching the age of 50.
Because Birkeland never kept a diary, documented information about his family and private life is sparse. Before he died, Olaf Devik, the last of Birke- ff
land’s close friends, gave a long interview and graciously transferred his per- sonal archive to A.E. Birkeland’s 82 scientific papers and three book-length publications map the progress of his investigations. We are grateful for the access granted to review the contents of many different archives. We greatly benefited from discussions with Professors Leiv Harang and Hannes Alfv´en as well as members of the Norsk Hydro staff. We are very grateful to Profes- sor Naoshi Fukushima for translating and making available to us Birkeland- related segments of Torahiko Terada’s diary. A.E. would also like to thank Espen Trondsen (University of Oslo) for computer assistance and Mrs L. Hedlund for T
language advice.
We also extend special thanks to the staffs at The Norwegian Technical Museum, the Alta Museum responsible for the Haldde Observatory, and to the Birkeland-Eyde Industrial Museum at Notodden for providing useful illustra- tions.
The authors express our special thanks to Ms Louise C. Gentile of Boston College Institute for Scientific Research for proofreading and editing our manuscript.
This book would have been impossible to write without the constant encour- agement of our families, professional colleagues, and friends. Our gratitude extends to all who made this book possible.
Alv Egeland William J. Burke W
W
INTRODUCTION: TEMPORA MUTANT ET NOS CUM ILLIS MUTAMUR
Our lives pass within confines that are brief in time and limited in range.
Miracles of modern medicine prolong our days; modern means of communica- tion and transportation extend our reach across the globe. Still we know limits.
Personal influence is restricted in duration and locality. Yet there are people, Mozart comes to mind, whose contributions to collective human experience extend beyond their prescribed times and places. We place before readers of this book, a synopsis of the life and contributions of such a man, Olaf Kristian Bernhard Birkeland, a Professor of Physics at The Royal Frederik University in Kristiania,1 the capital of Norway, near the beginning of the 20th century.
Our subtitle The First Space Scientist, places Birkeland’s life in the context of space exploration, half a century before “Sputnik” and “Apollo” entered our vocabularies.
Over the course of the 20th century “space” evolved in the public con- sciousness from the captivating science fiction of Jules Verne (1828–1905) to a practical reality that touches innumerable aspects of modern living. We plan our activities around weather forecasts based on images from satellites hovering about 36,000 kilometers above the Earth’s surface. How did this transformation come about? While it represents a triumph of rocket technology, much more is involved. Scientists had to devise and miniaturize electronic devices. This re- quired the development of new materials that could withstand and operate in the harsh radiation environments of space. Industry had to create new management and quality assurance skills to meet schedules of unprecedented complexity.
Every single mechanical and electronic component has to work within exacting specifications. Once launched, repair services are not available to replace failed components on a 100 million dollar spacecraft. The extraordinarily high cost of entry to space requires national and international investments and visions of future possibilities. The critical alliances among science, government, and industry needed to understand and operate in space were simply unimaginable as the 20th century began.
At the time scientists constituted a very small percentage of the total popula- tion. The vast majority of these were either associated with universities or inde- pendently wealthy. Of the former, teaching responsibilities usually outweighed
1In 1925, Norway’s capital reverted to Oslo, its name before the devastating fire in 1624. King Kristian IV of Denmark rebuilt the region and renamed the city. For 300 years, the city was called Christiania, but during the last period was spelled Kristiania, as used here.
2 INTRODUCTION
research opportunities. Still progress was made. As the 19th century concluded, practical implications of a newly discovered unity underlying electrical and magnetic phenomena were being grasped. Understanding, controlling, and uti- lizing the new world of electromagnetism challenged the contemporary imag- ination.
Scientists distinguish between phenomena in laboratory experiments and in nature. Laboratory investigators control experimental environments exact- ingly to test theoretical understanding and to identify new interactions. At the other extreme, astrophysicists can only measure the effects of natural forces that lie light years beyond human control and try to interpret observations in the light of known physical laws. Much of Birkeland’s story concerns hard won observations and bold interpretations of the natural interactions between the Sun and the Earth’s magnetic field that produce auroral displays and geomag- netic storms. Birkeland distinguished himself from contemporary investigators though laboratory simulations of natural electrical phenomena. Far ahead of his time, Birkeland’s prophetic concepts about the electric particles and cur- rents controlling the physics of space passed into decades of eclipse before re- emerging in the 1970s. Throughout the years of eclipse, Birkeland’s reputation remained strong in Scandinavia, although heated debates raged concerning the validity of his speculations about space. Even in principle, no resolution could be found before spacecraft probed altitudes above 100 kilometers. Birkeland’s reputation survived and flourished because he was the first to forge alliances be- tween science and the Norwegian government to investigate space, and between science and international industry to resolve an emerging crisis in feeding the growing global population.
Olaf Kristian Bernhard Birkeland was born in Kristiania on December 13, 1867 and died in Tokyo on June 15, 1917. Although his birth certificate reads “Christian”, as an adult he used only his second name, which he spelled
“Kristian”. In publications after 1898, he simply referred to himself as Kr.
Birkeland. Birkeland’s life spans a watershed period when insights about elec- tricity and magnetism, codified by Maxwell in the mid-19th century, evolved from theoretical curiosities to become the basis for electronic technology and eventually for our understanding of the geospace environment.
Friends and colleagues universally recognized Birkeland as a gifted man with a wonderfully inventive mind that bubbled with ideas and sought to inves- tigate every aspect of the physical sciences. In June 1890, Birkeland completed university studies in physics, graduating youngest in his class with the highest grades. In January 1893, he was awarded a universitetsstipendiat, equivalent to a Research Assistantship, at the University of Kristiania. Much of his early research was conducted in France, Switzerland, and Germany between January 1893 and August 1895. During this period, Birkeland published two theoretical
INTRODUCTION 3 papers that drew wide attention. His mathematical training in Norway provided a superb foundation for developing the first general solution of Maxwell’s equa- tions. He continued to investigate the properties of electromagnetic waves in conductors and wave propagation through space. At the age of 28, he was elected to be a member of the Norwegian Academy for Science and Letters. In the Academy’s 150-years history, only the famous Arctic explorer and oceanog- rapher Fridtjof Nansen (1861–1930) was elected at a younger age.
In October 1898, Birkeland was called by King Oscar II of Sweden to be senior Professor of Physics at the University of Kristiania. At that time, he was the youngest professor on the faculty. Because he looked younger than his age, for several years he was called “the boy professor”. In 1906, he was elected a fellow at the Faraday Society of London and in 1908 received an hon- orary doctorate, Doktor Ingenieur Honoris Causa, from the Dresden Technical University in Germany.
Birkeland married Ida Augusta Charlotte Hammer, who was four years his senior, in May 1905. She was a teacher of cooking at a girl’s school near Kristiania. They had no children and the marriage was not happy. They formally divorced in January 1911, after nearly two years of separation.
While Professor of Physics at The Royal Frederik University in Kristia- nia (1898–1917), Birkeland laid foundations for our current understanding of geomagnetism and polar auroras. In 1901, Birkeland initiated a new set of laboratory simulations that he called Terrella ExperimentsTT . He hoped to prove incontrovertibly the correctness of his theoretical interpretation of auroral and geomagnetic disturbances. For the first time cosmic phenomena were scaled and simulated in a laboratory. His terrella experiments were at once simple and in- genious. His largest chamber was a full cubic meter in volume. He fully believed that the laboratory simulations confirmed his understanding of auroras. They opened new paths suggesting how electromagnetic forces might operate in the solar system. Birkeland’s laboratory simulations were brilliant successes that allowed him to argue by analogy about the causes of auroras and geomagnetic disturbances. In 1899, Birkeland built the first permanent auroral observatory in northern Norway atop a 900-meter mountain. He conducted three auroral and geomagnetic expeditions between 1897 and 1903. Of these, his four-station polar expedition during the winter of 1902–1903 was the most important.
After 1906, Birkeland extended his terrella experiments and applied the electromagnetic theory to include solar and cosmic phenomena. His simula- tions of the influence of corpuscular radiation from the Sun on Saturn’s rings, and comet tails are fascinating, especially coming at a time when other scien- tists maintained that the Earth was surrounded by vacuum. His concepts of stars as sources of matter for interstellar space and the importance of electromag- netic forces throughout the cosmos are markedly less known. His theoretical
4 INTRODUCTION
Figure 1.
F
F King Oscar II appointed Birkeland Professor of Physics in October 1898. The appoint- ment was announced in a formal, four-page document. In accepting this appointment Birkeland promised to support royal authority.
proposals were rooted in laboratory experiments designed to simulate space in- teractions. Birkeland blended a unique intuition with talent for technical work.
His approach generated fruitful frameworks for understanding basic plasma processes.
Birkeland published eighty-eight scientific papers; thirty-two of them ap- peared in Comptes Rendus des Sciences, the journal of the French Academy.
The others were published in German, Scandinavian, and English journals.
He also wrote three scientific books. His main treatise The Norwegian Aurora Polaris Expedition of 1902–1903
P
P fills more than 800 pages in large format. The
other two books are about 200 pages in length. Research activities in many dif- ferent fields were new to Norway. As many as eight research assistants worked in his laboratory. Several scientists have ranked him among the world’s leading experimental physicists. (cf. e.g. Perattrr , 1996).
From 1901 to 1906 Birkeland turned to applied physics and technological development. His primary motive for engaging in this activity was to generate the funds needed to support ambitious research projects and to build a modern research laboratory whose cost greatly exceeded what the University could afford. All together Birkeland developed sixty patents in ten different subject
INTRODUCTION 5 areas. In one field, the production of agricultural fertilizers, he earned large sums of money. Birkeland invented the plasma arc leading to the Birkeland-Eyde method for industrial nitrogen fixation and the founding of Norsk Hydro that today remains one of Norway’s largest industrial enterprises. While Norwegians mostly remember him for his leading role establishing Norsk Hydro, Birkeland viewed the effort as a diversionary episode in his life.
Birkeland’s first patent concerned an electromagnetic cannon that is similar in concept to a rail gun. He then formed his first company called Birkeland’s Firearms. A modern rail gun was used to simulate how the Space Shuttle Columbia’s left wing was breached by a high-speed packet of foam. Birkeland also held patents related to electrical switches and even formed a small company for their industrial production. He also took out patents related to hardening whale oil to produce magarine, electromagnetic devices to probe for metals and w
minerals, the refining of oil, and mechanical hearing aids. In 1906, Birkeland applied for funds from international financiers in Stockholm to support research for utilizing atomic energy; in 1915, he sought support to build automated meteorological stations to improve severe weather predictions. From 1908 to 1910 he conducted extensive radiowave experiments related to telegraph and telephone technology. To help improve radio communications capabilities, at his own expense, Birkeland erected a 15-meter high transmitter antenna on the roof of the University’s main building and built receiving stations a few miles away.
Birkeland’s pioneering research in geophysics and applied physics engen- dered a widespread spirit of pride in his newly independent homeland. On February 1, 1913, the front page of the Aftenposten, Norway’s largest newspa- per, featured a summary of a lecture Birkeland had presented to the Norwegian Academy on the previous evening with King H˚akon VII sitting in the front˚ row. His ability to attract and stimulate young scientists laid the foundations for Norway’s strong presence in present-day space research.
Many of Birkeland’s insights about the physics of space passed unrecognized until satellites gave us the ability to survey electromagnetic environments be- yond our atmosphere. He introduced basic concepts that are central to modern space physics. They include calculations of energetic-particle motions in dipo- lar magnetic fields, his description of geomagnetic substorms, and his postulate that electric currents flow along magnetic field lines into and out of the upper atmosphere, today called the Birkeland currents. These currents link the upper atmosphere to the distant reaches of geospace. He also discovered the global pattern of the electric currents in the polar ionosphere. Based on his own lab- oratory simulations, Birkeland first suggested that how charged particles from the Sun control geomagnetic disturbances and might influence such interplan- etary phenomena as Saturn’s rings, comet tails, and zodiacal light. As space
6 INTRODUCTION
measurements accumulated in the 1970s, attitudes towards Birkeland’s work on electric currents in space changed to admiration and acceptance. In retrospect, we see that Birkeland’s geomagnetic and auroral research, conducted between 1894 and 1913, was decades ahead of its time.
Birkeland was tireless, energetic, and enthusiastic, constantly involved in simultaneous projects. Thus, he often worked both days and nights. He in- troduced innumerable ideas but never spared himself. He possessed a lively imagination and a sense of humor that tended toward self-deprecation. Some faculty colleagues were envious of Birkeland’s ability to attract generous gov- ff
ernment support for his research. He identified and employed many promising young students who grew to become important leaders in the Norwegian sci- entific community. Among these were Sem Sæland, Carl Størmer, Lars Vegard, Ole A. Krogness, Thorald Skolem, Karl and Olaf Devik. They all contributed to the development of cosmic geophysics, a new field of research started by Birkeland. He disliked the University’s formal criteria for appointing new pro- fessors, and often voted with the minority. Feeling that the University had too many German-speaking professors, Birkeland actively supported the candidacy of chemist Ellen Gleditsch, a former assistant to Madam Curie, to become the first female member of the faculty.
Olaf Devik (1971) described Birkeland’s lectures: “When he lectured on a subject which he was especially fond of, he brought a breath of fresh air into the classroom. He would operate electrical equipment far beyond their rated capacities and burn out 100 Ampere fuses with dignified nonchalance” (Devik, 1971). He seldom hesitated to disagree with explanations in physics textbooks.
As his research responsibilities grew, Birkeland found less and less time to prepare and give lectures, and often paid his assistants to teach introductory courses.
The concept of maintaining good health with regular exercise and a good diet was alien to Birkeland’s mind. He always worked hard, and his assistants often had to remind him to eat lunch. From his days as a student, he experienced frequent bouts of insomnia. Some of his early radiowave experiments led to serious hearing defects. In his later years, Birkeland grew even more absent- minded and disorganized in his daily life. He jotted small notes about schedules, budgets, and scientific ideas on single sheets of paper, then left them in random places. A rapid deterioration in his health was a critical factor in Birkeland’s decision to emigrate to Egypt in 1913. The last two years of his life were particularly difficult. He slept poorly and became inordinately suspicious of strangers.
Birkeland’s life also spanned a period of political change, from whose influ- ence not even theoretical physicists are exempt. Incorporated into the Swedish Kingdom in 1814 after the Napoleonic wars, Norwegians found themselves
INTRODUCTION 7 mired in a political and economic backwater. Between 1840 and 1900, more than 600,000 Norwegians emigrated to the United States. Others stayed and struggled for an independent Norway. Birkeland always viewed his scientific and applied work through the prism of Norway’s contribution to civilization.
Although he was very much a Norwegian nationalist, he was also a European cosmopolitan. In the summer of 1914, the century-long peace established at the Congress of Vienna collapsed while Birkeland was in Egypt conducting research on a solar effect called zodiacal light. His two young assistants were recalled to Norway for military service.
In early 1917, alone and in poor health Birkeland decided to return to Norway. The war dictated that he travel to Kristiania via Japan and the Trans- Siberian railroad from Vladivostok. His companion, Dr. Eriksen, the Danish Consul to Egypt, was on his way back to Copenhagen. However, when they reached Tokyo in early May, Eriksen changed his plans and returned to Egypt.
Birkeland died in Tokyo about a month later, an indirect casualty of the con- flagration we now call World War I. In the course of our research for this book, we uncovered documents from May and June 1917 that cast new light on Birkeland’s last days in Japan.
At the University commemoration of Birkeland’s death in 1917, Vice- Chancellor Sæland characterized Birkeland as “a scientific explorer by the grace of God.” In the eyes of all Norwegians he was both famous and wealthy.
At the time of his death, an international committee was in the process of nominating him for the Nobel Prize in Physics. Altogether he was nominated for a Nobel Prize four times each in chemistry and physics. The government of Norway honored Kristian Birkeland as the world’s first space physicist. His por- trait, along with his terrella experiment and some original drawings, appears on the 200 kroner banknote, first issued in 1994. In addition, a large international Birkeland Symposium was held in 1967, and the annual series of Birkeland lectures was established at the Norwegian Academy for Science and Letters.
Birkeland was the complete scientist, a gifted theorist, as well as an imag- inative laboratory and field experimentalist. He devised laboratory experi- ments that, for their time, were of unprecedented size and complexity, and he made them work. Many studies have been made of eminent scientists.
Some scholars are purposeful, follow straight lines toward their goals, and never allow interruptions or distractions. Others take a different approach.
Like gardeners who develop hybrid roses, they try many different methods and techniques with varying degrees of success. Birkeland belongs to this latter category.
To begin to understand Birkeland’s accomplishments and the arguments against them, we must set aside the technological world we take for granted and imagine ourselves at the end of the 19th century. We must continually ask,
8 INTRODUCTION
“What did scientists of the time know?” For example, although Birkeland began working with “cathode rays” in 1894, it was not until 1897 that Joseph John Thomson (1856–1940) identified them as the electrical corpuscles we now call electrons. With this knowledge, Thomson developed a model in which posi- tive and negative charge was distributed more or less uniformly throughout the atomic volume. However, Thomson’s model wrongly predicts atomic emission spectra. It was not until 1910 that Ernest Rutherford (1871–1937) experimen- tally demonstrated that atoms consist of electrons orbiting very small nuclei of positive charge. According to Maxwell’s equations, electrons in Rutherford’s planetary atom should radiate energy as light and collapse into the nucleus.
In 1913, Niels Bohr (1885–1962) took the first step toward understanding the quantum universe we take for granted today.
There is also a problem of language. The 19th and early 20th centuries were times of singular growth in scientific understanding. Reading early papers chal- lenges scientists accustomed to textbooks written after World War II. Standard terminology, mathematical notation, and physical units have now evolved that allow readers access to the thoughts of American, European, or Asian scientists without requiring mental gymnastics to map between them. However, reaching this stage of synthesis required the unification of partially described phenom- ena and diverse metaphors into a common nomenclature. Like any explorer, Birkeland had to invent new language as his research uncovered new layers of physics.
As the first to examine disturbance records from around the globe during magnetic storms, Birkeland estimated that currents of several millions Amperes must flow in the upper atmosphere. He understood intuitively that only the Sun could drive and sustain such large electrical currents. Consequently, currents in the upper atmosphere must connect to generators in deep space via mag- netically field-aligned currents. Indeed, Birkeland found the predicted currents replicated in laboratory simulations. He reached truly innovative conclusions about the physics of the aurora and disturbances in the Earth’s magnetic field.
Others shared neither Birkeland’s intuition nor his trust in laboratory simu- lations and felt they could explain magnetic perturbations observed on the ground as the results of a system of equivalent currents flowing in the upper atmosphere. Decades passed before Naoshi Fukushima showed in 1969 that it is impossible to distinguish between Birkeland’s and the equivalent-current systems based on ground magnetic records alone. Field-aligned currents can only be detected with magnetometers on spacecraft flying above ionospheric current layers. Scientists are human beings who may feel tribal loyalties that blind them to truths expressed in unfamiliar words. In 1892, William Thomson (1824–1907), better known as Lord Kelvin, expressed his opinion that no mat- ter passes between the Sun and the Earth. In spite of mounting evidence to
INTRODUCTION 9 the contrary, Kelvin’s opinion was definitively rejected only after satellites had passed though the boundary of the Earth’s magnetic field into the solar wind.
Writing a scientific biography of Kristian Birkeland about a century removed from the time of his greatest achievements presents two further difficulties.
First, Birkeland was an extraordinary theoretical, experimental, and applied physicist whose interests were both broad and urgent. Coming from a middle class family, he lacked the independent resources needed to support his scientific investigations. An international scholarship and his inexpensive but ingenious experiments at the University of Kristiania established his scientific reputation at a time when Norway sorely needed heroes. This renown provided entr´ee and´ credibility when he approached the Storting, Norway’s parliament, in search of funds to support challenging field experiments. It also attracted the attention of industrialists who approached the Norwegian WunderkindWW for advice in solving practical problems. In the first decades of the new century, Birkeland analyzed and published the results of his laboratory experiments while developing new practical concepts and demonstrations to support sixty patents. More and more Birkeland invested money earned from industrial inventions to support his scientific research. Because he was involved in so many projects at once, a simple chronological listing of events would lead to confusion. For this reason, we chose to pursue a thematic development.
A second difficulty arises from the fact that Birkeland never kept a diary.
Most of our knowledge of him as a schoolboy, as a university student, in his private life and marriage as well as his conflicts with Sam Eyde and Carl Størmer is largely based on the writings and recollections of his close assistants, Sem Sæland, Ole A. Krogness, and the Devik brothers, Olaf and Karl. They regarded Birkeland as a genius. One of the authors (A.E.) conducted extensive interviews with Olaf Devik and was given full access to his archives. In The Norwegian Aurora Polaris Expedition of 1902–1903, which we refer to asww NAPE, Birkeland does discuss the development of his thoughts concerning N
N
laboratory and field experiments. He also provides candid descriptions of and his reactions to physical hardships and dangers experienced during the auroral expeditions. In addition, he planned to write Volume III, mainly concentrating on auroral physics and the results of experiments with his 70-cm diameter terrella. Unfortunately, Birkeland died before this volume was written. Shortly after his death in Tokyo, colleagues assembled all of Birkeland’s scientific papers for return to Norway. The ship bearing the papers was lost at sea, and with it access to Birkeland’s mature thoughts on auroral phenomena.
At the present time, Birkeland’s name and contributions are not well known outside Scandinavia. External recognition is mostly confined to scientists who study the Earth’s space environment. Even among them, appreciation of Birkeland’s work is fragmentary, mainly concerned with the field-aligned
10 INTRODUCTION
currents that electrically couple the ionosphere to deep space. His laboratory simulations of the solar system and his technological innovations remain largely unknown. Lucy Jago’s book The Northern Lights (2001) is the most compre- hensive biography of Kristian Birkeland available in English. The book is well written in a journalistic style that necessitated telescoping events and, in the absence of documentation, making “reasonable” assumptions about what ac- tually occurred. It strongly emphasizes Birkeland’s personality and the reac- tions of others to him. We share much common ground. However, as auroral scientists, we emphasize Birkeland’s documented scientific and technological accomplishments and his place within the development of space physics over the past century.
This book is divided into five major sections, each with two or three chapters.
The first sets the stage with brief summaries of the political and scientific status of Norway at the end of the 19th century. It also describes the Birkeland family and Kristian’s education through postgraduate studies. The second section deals sequentially with Birkeland’s geomagnetic and solar system research. His ge- omagnetic studies were conducted during field expeditions and in laboratory simulations with the terrella serving as an anode to attract energetic electrons from the “Sun”. In his solar system simulations, Birkeland reversed the electric polarity of the terrella to simulate the origin of sunspots and comet tails. From these experiments, he came to a profound realization that the universe must be filled with ionized gas that we now call plasma. The third section deals with Birkeland’s technological inventions related to high-current switches, electro- magnetic cannons, and nitrogen-fixated fertilizers. The fourth and fifth sections, respectively, describe Birkeland the man as perceived through available docu- ments and interviews with Olaf Devik, and his heritage in Norwegian education and space physics. In addition to the standard references at the end of the book, interested readers can also find copies of several previously unavailable docu- ments as well as lists of Birkeland’s publications and patents.
Part I: Background and Education
CHAPTER 1
AT THE 19TH CENTURY’S END
1.1 UNION OF NORWAY AND SWEDEN
In the aftermath of the Napoleonic wars, England and Russia agreed that Norway should become a part of the Swedish kingdom. From the outset the Union was unstable. In 1814, the year of the forced union, Norwegians ratified their own constitution. They experienced two bothersome limitations to their autonomy. First, Norway was not free to appoint its own foreign ambassadors.
Second, their Swedish King held veto power over enactments of the Norwegian Storting (Norway’s parliament). Relations between Sweden and Norway dete- riorated severely in the first half of 1905, leading to the Union’s dissolution. On June 1, 1905, King Oscar II of Sweden vetoed a Norwegian resolution to form its own Consular Service. The Storting declared that the King’s action was unconstitutional. Existing law allowed the king to exercise a veto only with the concurrence of his cabinet. Norway unilaterally ruptured the Union on July 7, 1905, and waited anxiously to see if Sweden would declare war. In the months before the final break, the Storting prudently consulted with critical countries to assure international acceptance for their independence initiative. The world-famous Norwegian explorer and oceanographer Fridtjof Nansen (1861–
1930) helped carry the day by persuading the British government to support separation.
A September plebiscite, in which only men could vote, certified the degree of popular support for dissolving the Union. Almost unanimously Norwegians voted to end the Union, 368,208 for and 184 against. A second referendum, held in November, decided whether newly independent Norway would become a republic or remain a constitutional monarchy. Newspaper editors and other prominent citizens encouraged votes for a monarchy, hoping that a Swedish prince would be chosen as the king and thus maintain good relations with the strong neighbor. When the Swedish prince declined, Norway turned to the Danish prince Carl who accepted and assumed the Norse royal name H˚akon VII.˚
12 CHAPTER 1
Figure 2.
F
F The Royal Frederik University of Kristiania and University Square as they looked when Birkeland was a student. Birkeland’s office and laboratory were in the Domus Media, behind the column fa¸cade.¸¸
1.2 THE ROYAL FREDERIK UNIVERSITY IN KRISTIANIA In 1811, King Frederik VI of Denmark established Det Kongelige Frederiks Universitet (The Royal Frederik University) in Norway’s capital, Kristiania. It was renamed University of Oslo in 1939. Following Birkeland’s example in his main book, The Norwegian Aurora Polaris Expedition of 1902–1903, we simply refer to it as the University of Kristiania. In the beginning, the University was scattered throughout the city. The Astronomical Observatory (1832) was the first building specifically built for the University. In 1851, the University moved into the new Domus Media around which the main campus formed.
This was centrally located on the city’s main street, Karl Johan Gate 47 (Gate is the Norwegian word for street). At the beginning of the 20th century, it was still the largest building along the street. Figure 2 shows its impressive facade of columns and shallow steps. The Royal Castle and the Storting were¸¸
its nearest neighbors to the north and south, respectively. The physics group moved into Domus Media in 1851. Not long afterwards, two other monumental buildings were completed on the new campus. The main university library, Domus Academica, with several lecture halls lies to the west of Domus Media, and to the east is the first festival building later known as the Old Banquet Hall.
The Philosophy Faculty then had two major sections. The first concerned the disciplines of philosophy and history, the second mathematics and science. By 1860, an institute of physics was recognized with its own faculty. In 1891, the institute became the Department of Physics.
AT THE 19TH CENTURY’S END 13
Figure 3.
F
F Christofer Hansteen (1774–1873), the first professor at the University of Kristiania to study geomagnetism and auroral lights. A fascinating researcher, Hansteen had a profound influence on the University’s early development.
Christofer Hansteen (1784–1873), shown in Figure 3, was a character central to the University of Kristiania’s development. A Norwegian by birth, Hansteen received his scientific education at the University of Copenhagen under the direction of Professor Hans Christian Ørsted (1777–1851). We return to Ørsted and Hansteen in our discussion of geomagnetism. In 1816, Hansteen returned to Norway to become the University’s first Professor of Astronomy and Applied Mathematics. He was the driving force responsible for building the Astronom- ical Observatory on land that would become a part of the University campus.
By 1885, when Birkeland entered the University, the total number of students and faculty was nearly 600. There was a single Professor of Physics, Oscar Emil Schiøtz (1846–1924). However, Birkeland worked more closely with Carl Anton Bjerknes (1825–1903), Professor of Applied Mathematics and father of his friend Vilhelm Bjerknes (1862–1951). The younger Bjerknes later gained international fame for his work on the meteorology of weather fronts. Two other professors who greatly influenced Birkeland were Hans Geelmuyden (1844–
1920), head of the Astronomical Observatory, and Henrik Mohn (1835–1916), director of the newly established Meteorological Institute.
1.3 EARLY INVESTIGATION OF THE AURORA AND GEOMAGNETISM
The beauty and mystery of shimmering auroral lights in the polar sky have long fascinated humanity (cf. e.g. Brekke and Egeland, 1994). These glorious
14 CHAPTER 1
lights have many names. In his treatise on Meteorology, Aristotle (384–322 B.C.E) referred to them asχασ µατα (chasms or cracks in the sky) shining with blood-red light. For the Vikings, they were simply “northern lights”. Early modern scientists such as Galileo (1564–1642) and Pierre Gassendi (1592–
1656) used the Latin aurora borealis or “northern dawn” to describe their red appearance at the latitudes of southern Europe. In 1770, during the voyage of Endeavor, Captain James Cook (1728–1779) was the first European to observe auroral lights in the southern hemisphere (aurora australis). Birkeland used the term aurora polaris to indicate that auroral phenomena occur at magnetic high latitudes in both hemispheres.
For many centuries, the magnetic properties of lodestones and magnetite were known and used as navigational aids. William Gilbert (1544–1603) con- ducted the first systematic investigation of the Earth’s magnetic field and pub- lished the results in De Magnete (1600). His most important conclusion was that “the Earth itself is a large magnet” with its greatest strength at the poles.
Gilbert also noted that the magnetic poles are displaced by a few degrees from the geographic poles. Scientists [Gilbert (1600); Gauss (1839, 1841); Chapman and Bartels (1940)] long recognized that the Earth’s magnetic field changes continually and often violently.
When Galileo first turned his telescope on the Sun in 1610, he discovered that it lacked the perfectly smooth surface postulated by Aristotelian cosmology.
Rather it was pocked by blemishes now called sunspots. Thereafter, the behavior of sunspot activity was carefully monitored. However, it was not until the 1840s that Heinrich Schwabe (1789–1875) showed that the number of sunspots varies considerably over an 11-year cycle.
In 1716, Edmund Halley (1656–1742) found a close association between geomagnetic disturbances and visible auroral displays. During the year 1741, Anders Celsius (1701–1744) and Olaf Peter Hiorter (1696–1750) conducted investigations in which they noticed that the orientation of a suspended mag- netic needle tilted either to the left or right of the geomagnetic pole direction whenever auroral lights were visible. Clearly, auroral perturbations of com- w
w
pass directions posed serious threats to navigation. However, Celsius could not explain why an auroral display affected compass directions. More than a cen- tury later, Birkeland proposed the first scientifically correct explanation of this mysterious relationship. He argued that fluctuations of the geomagnetic field m
m
provide critical information about the electrical currents flowing in the Earth’s space environment and about activity on the Sun. While the Earth’s atmosphere protects us from hazardous radiation, most information carried by magnetic field variations reaches the ground.
During the early years of the 19th century, while Christofer Hansteen was studying at the University of Copenhagen, the Danish physicist Hans Christian
AT THE 19TH CENTURY’S END 15 Ørsted (1777–1851) was examining changes in the orientations of magnetic needles whenever electric currents flowed in nearby wires. In 1820, Ørsted pub- lished his discovery that electric currents cause magnetic disturbances. Later, Michael Faraday (1791–1867) demonstrated that time-varying magnetic fields induce electric currents. James Clerk Maxwell (1831–1879) unified the work of Ørsted and Faraday, expressed in four fundamental laws of electromagnetism.
As Ørsted’s student, Hansteen was aware that Halley detected similar deflec- tions of compass needles during auroral displays. In 1812, Hansteen entered a European competition to answer the question: “Can we explain the Earth’s magnetic phenomena with a single magnetic axis, or must several axes be as- sumed?” Hansteen’s (1819) thesis Untersuchung ¨uber den Magnetismus der¨ Erde won the competition. He concluded that two axes, or four magnetic poles were needed to explain existing measurements of the Earth’s magnetic declina- tion. The concept of a quadrapole magnetic field was not new. Hansteen cited it as part of Halley’s geomagnetic model, and he spent a good deal of time trying to determine where to place the four poles on a globe. Hansteen built several new instruments for measuring the total field and the magnetic declina- tion to support his geomagnetism studies. Between 1828 and 1830, he traveled across Siberia to China to look for the second pole on the northern hemisphere.
Although he never found a fourth magnetic pole, the global magnetic map he derived during this expedition was of considerable use to Carl Friedrich Gauss (1777–1855).
Although the auroral problem was not of central interest to Hansteen, in 1825, he surmised: “The northern lights must be part of a shining ring, with a diameter of about 4,000 kilometers, of which each observer sees his own segment. This leads us to suppose that there must be some connection between the aurora and the Earth’s magnetism.” (cf. e.g. Tromholtrr , 1885). Much later in the 19th century, Herman Fritz (1830–1893) in 1881 clearly documented that the auroral lights most often occur about 23◦from the magnetic poles.
Systematic recordings of simultaneous geomagnetic field variations began in 1834, when Carl Friedrich Gauss first deployed magnetometers of the Gøttingen Magnetic Union at stations around Europe. Gauss’ publication Algemeine The- orie des Erdmagnetismus (1839) initiated the modern study of geomagnetism by applying the gravitation potential theory of Pierre-Simon Laplace (1749–
1827) to the Earth’s magnetic field. Gauss argued that magnetic fields detected on the ground have sources inside Bint and outside Bext the Earth. He then demonstrated a mathematical technique to separate them. He concluded that Bintwas due to a large, permanent field from inside the Earth that varies from ap- proximately 30,000 to 60,000 nanotesla (nT) between the geomagnetic equator and the poles. The magnetic-field axis tilts about 11◦to the Earth’s rotational axis. To a good approximation, the geomagnetic field is represented by a simple
