Studies in Hamburg 1945–1954

Abstract

In September 1945, Herwig began his studies at the University of Hamburg. Frau Palm had offered him lodgings in the suburb of Hamburg-Farmsen, and the first thing he did once he’d secured somewhere to stay was to apply for a place to study physics and mathematics. He still had his job as an interpreter for the British Military Government, so he had a source of income. He’d carried a copy of his Maturity certificate with him throughout the war, and his excellent grades were good enough to secure him a place.

In September 1945, Herwig began his studies at the University of Hamburg. Frau Palm had offered him lodgings in the suburb of Hamburg-Farmsen, and the first thing he did once he’d secured somewhere to stay was to apply for a place to study physics and mathematics. He still had his job as an interpreter for the British Military Government, so he had a source of income. He’d carried a copy of his Maturity certificate with him throughout the war, and his excellent grades were good enough to secure him a place.

Fig. 3.1

Herwig in his first civilian suit after the war. Photograph taken in the late 1940s in Hamburg (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

He’d been lucky to apply as early as he did. The university was in ruins, and soon after Herwig was accepted, the university imposed two conditions on applicants. First, they had to have been living in Hamburg before the war, and second, they had to spend six months clearing up the of ruins of the campus before they could start their academic work.

These conditions did not apply to the early applicants, but the conditions for learning were nevertheless difficult. With a full-time job, he had to be selective about which lectures to attend and which to skip. Those he did attend were often crowded, and students would be sitting on the steps of the lecture halls, or peering around doors to see what the lecturer was saying. One in particular had a peculiar price of entry to his classes. “The lecture halls were not heated,” Herwig recalls, “so Lenz always wore a scarf, and he put up a sack at the entrance to the lecture hall where every student had to put a piece of coal, or any other heating material, to help heat his living quarters.”

Fig. 3.2

Herwig as a student at the University of Hamburg in around 1948 (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

The students benefited from this too. Tutorials were given in Lenz’s apartment, in a high-ceilinged and draughty room in which the professor had constructed a small cardboard cubicle around a small coal-fired stove. “When I was examined by him, I had to sit in this little cubicle, sweating next to the fire—from the heat as well as his questions.”

The Lenz in question was none other than Wilhelm Lenz, who had been a student of, and then an assistant to, the great Arnold Sommerfeld before becoming director of the Institute of Theoretical Physics in Hamburg. Among his assistants in Hamburg was Wolfgang Pauli, and Lenz maintained strong links with Niels Bohr in Copenhagen, Max Born in Göttingen, as well as his old supervisor, Sommerfeld, in Munich.

Fig. 3.3

One of Herwig’s first teachers, Wilhelm Lenz. “I learned 80% of the physics I know from him,” recalled Herwig. “A great physicist who is too little known today” (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

Ernst Ising was Lenz’s student. The famous Ising model of ferromagnetism was in fact an idea of Lenz’s, given to his student as a problem. “Ising simply carried out the computation that Lenz asked him to do,” said Herwig, “so it should really be called the Lenz–Ising model.” Lenz remains to this day one of Herwig’s favourite teachers, but that’s an appreciation that only developed over time. Lenz was not a loquacious teacher, but rather an assiduous user of the blackboard. “I only realised much later how fantastically thought out his lectures were,” said Herwig. “He really concentrated on the fundamental aspects of physics, and even today if I have a question on fundamental physics, I look at my notes from his lectures. Probably 80% of my knowledge of theoretical physics goes back to the lectures of Lenz, and I only came to realise this much later.” There’s a lesson in this, Herwig believes, for those who advocate the kind of rapid and immediate evaluation of teachers that’s fashionable today. “I believe that one should not give too much weight to the opinion of students—they understand only much later from which lectures they benefitted most.”

Herwig began his studies full of confidence, but was soon brought down to reality. Mathematics at university turned out to be a very different proposition to mathematics at the gymnasium in Landskron, so although he’d mastered the rudiments of calculus at school, at university, he found himself immersed in a whole new vocabulary running from n-dimensional vector analysis to epsilontic reasoning. “I thought the first semester would be rather easy, but to my great surprise, after the first few lectures, I realised I had not understood a single word,” he admitted. “It took me quite some time to get used to the scientific language and thinking at the University.” But get used to it he did, often working late into the night in the Palm family’s kitchen table in Hamburg-Farmsen.

In experimental physics, the first semester of the 1945–1946 academic year was to have been taught by Peter Paul Koch. A student of Wilhelm Röntgen, Koch became a professor at the University of Hamburg when it was founded in 1919. During the war, Koch had been an active National Socialist, and although released by the British before the semester started, he chose to take his own life in October 1945, leaving a vacancy to be filled.

The university recruited a retired professor from East Germany, In reality, however, the lectures on experimental physics were delivered by a technician with no formal physics education but years of experience in preparing demonstration experiments. “He was well able to give the lectures,” recalled Herwig, “and they were very popular.” The lecture hall was built for around a hundred students, but every day around double that number tried to get in. “Since I was still working for the Military Government, I often came too late to get in. Soon I gave up and did not go to the lectures at all—I just made sure I got the signature of the Professor at the end of each semester as proof that I’d attended the course.”

Things took a decided upturn for Herwig with the arrival of Rudolf Fleischmann, a physicist with an excellent track record in research. Born in Erlangen in 1903, Fleischmann worked on isotope separation in Strasbourg during the war. Arrested by the Americans in 1944 because of the relevance of his work to nuclear energy, he spent the last months of the war as a prisoner in the US. Given the benefit of the doubt concerning his political convictions, he returned to Germany a free man in 1946 and went on to have a glittering career, both as teacher and as researcher, first at Hamburg, and then in his native Erlangen. In 1957, he became publicly known as a signatory of the Göttingen Manifesto, which argued against arming the German military with tactical nuclear weapons.

For Herwig, Fleischmann soon became a role model as someone whose curiosity was not limited to a single branch of physics. He’d started his career as a student of the nuclear physicist Walter Bothe, who later won the Nobel Prize. From there, he’d gone on to become an assistant to Robert Pohl, a leading solid-state physicist in Göttingen. “Because he’d worked with both Bothe and Pohl, Fleischmann was not specialised in one area or another,” explained Herwig. “He’d acquired and retained a wide understanding, and this impressed me very much. I tried to follow his example all my life—it’s really the unity of physics that makes it beautiful.”

As well as being appointed to the university’s Chair of Experimental Physics, Fleischmann also became director of the Physikalische Staatsinstitut, the state physical institute. Initially, nuclear physics was not allowed in Germany, and Fleischmann had to draw on the broad scientific culture that so inspired Herwig Schopper, but as alliances evolved and the Cold War began, restrictions eased and he was able to establish the university as a centre for nuclear physics.

In the early days of his tenure at Hamburg, however, Fleischmann had other things to occupy him. Along with the directorship of the state physical institute came a responsibility to advise the authorities of the State of Hamburg on questions related to physics, such as weights and measures, which are vital to the livelihood of a trading city. After the intensive bombing of German cities at the end of the war, the role took on the altogether more pressing task of bomb disposal. During Operation Gomorrah in 1943, Hamburg had received some 9000 tons of bombs, and many of them were still there, continuing to threaten the lives of the city’s remaining inhabitants until long after the war was over. Herwig and his fellow students found themselves devising ways of safely seeking out unexploded ordnance and making it safe.

Herwig Schopper first came to the attention of Rudolf Fleischmann when he registered for his pre-diploma examination, which students sat after two years of studies. The role of the pre-diploma was to select those students worthy of continuing towards a career in research, and Herwig passed with flying colours. “I passed the exam in the fall of 1947, apparently with excellent grades, since Fleischmann immediately offered me a job as a part time auxiliary assistant with the task of preparing experiments for the lectures and taking care of students in practical classes.” When Fleischmann later secured sufficient funding to build a new lecture hall, Herwig had an important role to play. “It was really revolutionary,” he explained. “The emphasis was given to the possibility to demonstrate experiments and not restrict physics teaching to explanations in chalk on the blackboard. I helped to design the layout of the lecture hall and became responsible for the demonstration of experiments. I spent many evenings trying to get a demonstration to work for a lecture the next morning.”

Fleischmann’s hands-on approach had been acquired during his time at Göttingen, where he had been introduced to the new teaching style of Robert Pohl, which became famous at the time and changed the style of experimental physics lectures in Germany. Pohl believed that physics should not only be taught on a blackboard, but that the main phenomena should be demonstrated to the students through experiments. “The experiments were sometimes very sophisticated and their preparation took a long time, because we had to be sure that they would work next day, otherwise the students would just have fun in criticising the failed experiments rather than learning anything.” Fleischmann also considered it important for students to become familiar with some phenomena even if the detailed theoretical understanding was beyond an introductory course. “This became my first employment in science, and though it was only part time with a ridiculously low salary, it was least enough that I could give up my job at the Military Government and devote my time to physics.”

A Diploma in Optics

Fleischmann assigned Fritz Goos, who had been working on optical spectroscopy at Hamburg since the early days of the university, to be Herwig’s tutor. Goos was a well-known name in the field of optics, thanks largely to work undertaken during the war years with his student, Hilda Hänchen. The Goos–Hänchen effect is a curious phenomenon linked to the total internal reflection of light at a surface between a dense and a less-dense medium. At a certain angle of incidence, all the light is reflected and nothing gets through. What Goos and Hänchen observed is that light that is totally reflected by a dense medium such as glass appears to penetrate a very small distance into the glass before being reflected such that the reflected light is slightly laterally displaced from the point of incidence. This turns out to be due to a phenomenon whereby the incident light becomes a so-called evanescent—literally vanishingly imperceptible—wave that propagates parallel to the interface. The Goos–Hänchen effect was first reported in Hilda Hänchen’s 1943 dissertation, and definitively written up in Goos and Hänchen’s 1947 paper, Ein neuer und fundamentaler Versuch zur Totalreflexion, in the journal Annalen der Physik. That their names remain relatively obscure in modern-day physics circles, despite the fact that the Goos–Hänchen effect is important in many aspects of modern optics, including laser-driven particle acceleration, may be down to the fact that following the wars, the language of scientific publication was shifting from German to English. An English version of their 1947 paper exists in the CERN library [1], but it was not translated until 1972. As this effect exists for all electromagnetic waves it later became interesting for applications such as radar.

Working under Fritz Goos meant that Herwig not only had a very rigorous training in experimental physics, but also an excellent mentor in Hilda Hänchen. She was married to one of the assistants at the institute, Albert Lindberg, who was also a physicist, and Herwig struck up a life-long friendship with them both.

“Goos was an experimenter of the old school,” recalled Herwig. “The first thing he told me was that you should never put your trust in dark boxes whose behaviour you do not know exactly, but rather you must understand all the experiment’s parts.” Thus began Herwig’s apprenticeship in techniques such as glass blowing, required to construct vacuum equipment, the technical skills required to make sensitive devices such as electrometers to measure electric charge, and techniques required to operate a precision balance to measure very small weights. “This approach would of course be unthinkable today, with the big instruments and collaborations where everyone has to trust in black boxes doing what they are expected to do, and in the expertise of others,” said Herwig. “Glass blowing is no longer part of the undergraduate physics curriculum, but this practical training helped me a lot over the following years.”

With the equipment available at the university, coupled with limited funds for research and the fact that even teaching nuclear physics in German universities was banned, Herwig chose a topic in optics for his diploma thesis following a proposal from Fleischmann. This would be the qualification to set him up for a career in industry, and is roughly equivalent to a Master’s degree today. Rudolf Fleischmann had many ideas—some excellent, some impractical—and to sort them out he often used his assistants. That’s how Herwig found himself working on a problem that Fleischmann had been pondering since his time with Pohl in Göttingen, where they’d observed that the structure of thin layers of alkali metals, such as lithium and sodium, is different to that of the bulk material. Pohl had speculated that alkali metals might have two different crystal phases, one of which was manifest in the bulk, the other in thin layers. “My task was to investigate the optical properties of thin alkali metal layers as a function of their thickness to find out whether Pohl was right or wrong.”

The institute was well equipped for optical research, but for the kind of precision that Herwig would need, there was one piece of equipment missing: an optical bench to provide the stability required for the kind of precision measurements he would have to make with interferometry. The solution came from a rather surprising direction. “Goos found out that near to the institute there was an old cemetery that had been badly damaged by bombs during the war, and was being closed,” explained Herwig. “Large marble gravestones were being sold off cheaply, and Goos got several of these. By putting such slabs of marble on three tennis balls one got something which was almost as stable as a modern optical bench, and it served my needs well. All the work for my diploma thesis and later for my Ph.D. was done on gravestones.”

Fig. 3.4

At Hamburg University after the war, equipment had to be improvised. Herwig’s optical bench consisted of a gravestone bought from a nearby bombed churchyard, supported by tennis balls (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

The technique that Herwig was asked to develop involved shining light on layers of alkali metals of varying thicknesses and studying the reflected and transmitted light. Previous work of this kind had considered the relative change of phase between vertically and horizontally polarised light on reflection, but Fleischmann thought that more insight could be gained into the structure of the sample by measuring the reflected and transmitted phase shifts independently for each of the two orthogonal linear polarisations: the shift in the so-called absolute phase. To do this, Herwig had to have a way of comparing his measurements with a reference beam of light that did not impinge on the metal layers. This required setting up a system of two beams, initially the same phase so that a definite interference pattern could be produced between the reflected or transmitted beam and the reference beam, thereby allowing the phase difference between the two to be determined. In order to get clear interference fringes, the intensity of the two beams had to be comparable and this was achieved with a special device. This had not been done before, and developing the techniques to make such measurements was the task assigned to Herwig for his diploma, which he received on 1 March 1949, paving the way to a Ph.D. studentship.

Restrictions on Nuclear Research in Germany Relax

After the war had been over for three years, the restrictions covering nuclear physics in German universities were relaxed. As a result, Fleischmann was able to introduce some teaching on the subject, although research remained out of the question. In 1948, he had hired one of the world’s pre-eminent experts on the matter, Erich Bagge, who had been a student of Werner Heisenberg, and was among the German scientists interned along with Heisenberg by the British at Farm Hall near Cambridge after the war, as the allies tried to understand the extent of the German wartime nuclear programme. Otto Hahn was another internee at Farm Hall. In 1938, Hahn, a chemist, working with Fritz Strassmann in Berlin had been the first to observe nuclear fission, although they did not immediately recognise it as such. They reported their observations to Hahn’s long-time colleague, Lise Meitner, who as a Jewish physicist had fled Germany for Sweden. She and her nephew Otto Frisch provided the interpretation—when Hahn and Strassmann had bombarded uranium with neutrons, and observed that the lighter element barium had been produced, the process was due to the fission of the heavy uranium nucleus into two lighter nuclei, along with three neutrons and the release of energy. They published this interpretation in the journal Nature. Despite the fact that four people had contributed to the work, the effect became associated most strongly with Hahn and Meitner, and it was Otto Hahn alone who was awarded the Nobel Prize for Chemistry in 1944, making Lise Meitner one of the most notable absentees from the list of those to receive one of science’s most prestigious awards. Somewhat ironically, Hahn accepted his prize while incarcerated at Farm Hall. Herwig would later learn about these events from none other than Meitner herself, when he spent some time working with her in Stockholm (see Chap. 5, A sojourn in Stockholm with Lise Meitner).

By this time, Herwig was developing an interest in nuclear physics, but by the time he concluded his diploma work and moved on to a Ph.D., it was still impossible to conduct experimental research in the field. “Fleischmann was trying to establish some experimental nuclear physics in the institute,” he recalled, “and later he proposed a Van der Graaf accelerator. This came too late for me because when this machine came into operation I had already left Hamburg.” Instead, Fleischmann encouraged Herwig to follow his diploma work through to a conclusion and test Pohl’s hypothesis that the alkali metals have a different crystal structure in the form of thin films than they do as bulk matter.

“By determining the optical constants, the index of refraction and absorption, as a function of the thickness of the metal layers produced by evaporation it was possible to explain the measurements by assuming that the thin layers are not deposited immediately as bulk metal but produced by condensation in the form of tiny droplets,” Herwig explained. “At first little droplets are formed, and these later join together to form bulk metal layers. The droplets are smaller than the wavelength of the light we used, which only sees the average density of the layers, resulting in apparent anomalous optical constants. Today this explanation is fully corroborated by electron microscope images where one can actually see the individual drops.” In his Ph.D. thesis, Herwig Schopper had demonstrated the hypothesis of Robert Pohl to be incorrect, and in doing so, he had developed a range of formulae for transmission and reflection from thin single layers, and for multilayers, valid for all kinds of electromagnetic waves. Herwig’s results were published in Zeitschrift für Physik. “These formulae became important not only for my own work, but they also became useful in completely different fields. To my surprise I found out many years later that they were rediscovered. Obviously people don’t read old publications, in particular if they were published in German, in journals like Zeitschrift für Physik or Annalen der Physik.” Herwig’s work, like that of Goos and Hänchen before him, had suffered from the wartime hollowing out of German science, as the world’s scientific communities looked elsewhere for new developments.

The move from diploma to doctorate was accompanied by a promotion from part-time to full-time assistant to Rudolph Fleischmann, which had important consequences for Herwig both in his professional and private life. Although unable to pursue experiments in nuclear physics, he was able to join in conversations with Fleischmann and the growing team of nuclear physicists he was assembling in Hamburg. “Fleischmann’s head was full of ideas,” remembered Herwig, “as always some were excellent and some were crazy, and it became the job of his colleagues to test them.” One such idea stemmed from Fleischmann’s time studying nuclear reactions with Walther Bothe. Just as he’d pointed Herwig in the direction of exploiting the experimental power of polarised light for his thesis, Fleischmann also thought that polarised particles would provide a more powerful tool for investigating nuclear reactions. This was a new idea at the time, but is ubiquitous in particle physics today. At the time, there was no known method to produce a polarised particle beam. Herwig tucked the idea away in his head for future reference.

In the 1920s, Otto Stern and Walther Gerlach had demonstrated the quantisation of electron spin in one of the landmark experiments from the early years of quantum mechanics, and Fleischmann wondered whether a Stern–Gerlach experiment could be adapted to produce polarised proton beams He asked his assistant Herwig to develop such a system. “It took quite some effort and time to convince myself, and to prove to Fleischmann that a Stern–Gerlach experiment works only for electrically neutral atomic beams and not for charged particles like electrons or protons,” said Herwig. The experience nevertheless proved useful to Herwig later, because it had led him to study developments subsequent to the Stern–Gerlach experiment, and in particular the Nobel Prize-winning work of Isidor Rabi, who invented the atomic molecular beam magnetic resonance method to study atomic spectra. This is the technique that today underpins the powerful medical imaging tool, magnetic resonance imaging (MRI). Back in the early 1950s, it led to Herwig suggesting to Fleischmann that a modified MRI technique, rather than the simple Stern–Gerlach setup, could be adapted to produce a polarised particle source. Later, when nuclear physics experiments were once again permitted in Germany, Herwig would use this knowledge to build just such a device. “I was intrigued by Fleischmann’s ideas,” remembered Herwig, “so alongside my doctoral work, I started to build a proton source. It did not provide polarised protons, but the experience came in useful later.”

Fig. 3.5

Herwig working on his polarised proton source in Hamburg in the early to mid 1950s (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

Another of Fleischmann’s questions for his team proved to be an important life lesson for Herwig. “I thought classical optics was old-fashioned and I was impatient to complete my thesis and move in the direction of more promising nuclear physics. Only much later did I realise how difficult it is to judge whether a field has become obsolete or not.” The question that led Herwig to that conclusion concerned coherent and incoherent reflection of light from alkali metals, and specifically, at what point along the transition from the gaseous start of the metal towards increasing density does the reflected light become coherent. “One of my colleagues, his name was Heinrich Deichsel, was charged with investigating this experimentally. He measured the light reflected from alkali gases in a glass vessel as a function of the gas density. Not much was achieved, but in a way, he was ridiculously close to the idea of ‘lasing,’ which gives us lasers today. Anyway, I decided to quit optics just a few years before the laser was invented and optics again became a blossoming field. From that experience I learned that one should be very careful when judging a field of physics to be obsolete.”

Formative Years

Herwig remembers his days as an assistant to Rudolph Fleischmann in Hamburg as formative for many reasons. In accompanying Fleischmann to conferences, he was able to meet many of the leading figures of twentieth century physics, among them Max Born, Werner Heisenberg, Robert Pohl and Arnold Sommerfeld. Thanks to the efforts to establish the University of Hamburg as a leading scientific and technical university, he also had the chance to rub shoulders with quantum pioneer Pascual Jordan, and among his Ph.D. examiners was the eminent physical chemist, Paul Harteck, who invented the technique of separating uranium isotopes using centrifuges. Harteck was another of those who had spent some months at Farm Hall after the war. Herwig remembers his Ph.D. examination vividly. “In order to embarrass me, Harteck asked a question that I could not answer. It was only after giving me an excellent grade that he confessed that the answer was only to be found in a paper of his, soon to be published.”

In Hamburg, Herwig established many life-long friendships with fellow students and university employees. Among them was Rudolf Kollath, an applied physicist, and later professor at Mainz. “His wife was an excellent violinist and we played together quite often,” said Herwig. There was also Albert Lindberg, Hilda Hänchen’s husband, who went on to be responsible for the development and production of scientific demonstration equipment for schools at the firm of Linde in Köln, and Hugo Neuert, later a renowned nuclear physicist. Herwig’s contemporaries as students included Gerhard Hertz, a great nephew of Heinrich Hertz, who became a professor in Münster, and Reimer Witt who went into industry and made a name for himself at Philips producing television sets.

Herwig received his doctorate on 9 April 1951 and with the exception of a year spent in Stockholm working with Lise Meitner, he remained in Hamburg until 1953. That year, Fleischmann received an attractive offer for a chair at the University of Erlangen. “Since this was his home town,” said Herwig, “he accepted. He offered me a post there and I went with him.”

In His Own Words: Family Matters

“My years in Hamburg were important not only for the development of my career in physics, but also for personal reasons. When I look back on that time now, I’m struck by how lucky I was, and how easily my career could have taken a completely different turn. It was also in Hamburg that I re-connected with my family who were dispersed around Europe after the war, and that I met my wife Ingeborg, with whom I shared the happiest 60 years of my life.

Before talking about how we met, I’d first like to describe a somewhat strange but important event in my life. After the war, I was a displaced person since my family had been expelled from Czechoslovakia. I didn’t know where they were, and they didn’t know where I was. We had no contact, and only rediscovered each other when the postal service between Germany and Italy was re-established. I had relatives in Italy, in particular an aunt, a sister of my mother, and from her I learned where my father and my mother were living. They were both safe and well, in separate towns: my mother in in a little town in Bavaria and my father at Wittenberg, the town where Martin Luther had lived. I told my aunt what had happened to me and what a difficult life I was having immediately after the war. My aunt’s husband was a sea captain, who commanded a commercial ship after the war transporting coal from Poland to Italy. Why do I tell you all this? Well, to avoid sailing around the Jutland peninsula, my uncle’s ship had to pass through the Kiel canal, which links the Baltic Sea to the North Sea. This canal has many locks, and one of the largest is at Kiel, which has a big harbour. One day, I received a letter from my aunt saying that my uncle could pick me up at the Kiel lock as a stowaway and take me illegally to Italy. Since life in Hamburg at that time was still extremely precarious and difficult, with little food and little hope of making a living, and since I faced an uncertain future in Germany, I considered this offer very seriously and I agreed to go. So, with just a small bag containing my belongings, I set off from Hamburg to Kiel and waited near the lock for the arrival of my uncle’s ship. Of course, he had told me when he expected to arrive, but ship navigation was rather uncertain in those times. I waited there but he didn’t come. Fast communication was impossible—no mobile phones in those days, and normal telephony was also practically not available.

I waited for several days but he did not arrive. Finally, I learned that because of heavy fog, all shipping had been stopped. Since it was not clear how long the fog would last the arrival of my uncle became very uncertain. I could not stay away from Hamburg too long because I would have lost what security I had with my job with the Military Government, and I could not interrupt my study at the university for too long if I wanted to continue there. So, I decided to give up this fantastic possibility, and go back to my life in Hamburg, whatever it may hold. Imagine what would have happened if there had been no fog! My life would have probably taken a completely different direction. So sometimes life is determined by chance, and there is little we can do about it. With hindsight, I’m very glad for those days of fog.

Let me tell you the second incident that determined the course of my life. During my time at the Military Government, I met a young German lady by the name of Ingeborg Stieler in the elevator. Somehow, there was an immediate spark between us, and we noticed a certain mutual empathy. We met again and I learned that she was also working for the Military Government as an English secretary. After some long walks along the river Elbe and several visits to the Hamburg opera house, which had been seriously damaged by bombs and had started some performances using the former stage as an auditorium, we got to know each other quite well.

After many discussions and some hesitation due to the precarity of our situation, we came to the conclusion that we should marry, which we eventually did, and were married for a long and happy 60 years. However, we agreed that the marriage would have to wait until I had a real job to support a family. This sounds very old-fashioned today, but back then it was the norm. We didn’t have to wait too long, since this condition was at least formally fulfilled after I passed the diploma examination in 1949 and was employed as assistant at the institute. However, other problems had to be solved before we could marry. Certainly, we wanted to have the agreement of the father of my future wife. He was in the import–export business like many people from families living in Hamburg for generations. Like most of the rest of the population at this time, he knew what a lawyer or a medical doctor did but he had no idea what the chances of a physicist were, and whether such a person could support a family. After some hesitation, and after he got to know me, he agreed to the marriage. His agreement was also essential for a practical reason. Living accommodation in Hamburg was strictly rationed and controlled. Space was limited to about eight square metres per person in the still half-destroyed town, and to find housing for a newly wed couple was practically impossible. Ingeborg was living with her father and her sister in a modest apartment since their house had been completely destroyed during the war. The apartment had two living rooms, a bedroom, a kitchen and a bathroom. Because of the shortage of accommodation, my father-in-law-to-be had been obliged by the authorities to let one of the rooms, and it was occupied by a young man who, among other things, was training to be an opera singer.

We tried to get approval from the authorities to give notice to the opera singer and make his room available for us. But when we went to see the people at the municipal authorities, the first person we spoke to told us that our marriage was our private matter and had no bearing on the rules concerning the distribution of accommodation. We should share the room with the singer, he told us. This was not a joke! Of course, we were very unhappy and went to see his superior, who turned out to be much more reasonable and understanding and agreed that we could have one room of the apartment. So at least we got a roof over our heads, but life in the small apartment was not so easy. Only several years later did we manage to get a larger living space, more independent, but still with only a kitchen corner and no separate bathroom.

We were married on 14 March 1949 at Hamburg-Eppendorf, just two weeks after I’d received my post as an assistant at the institute, but the first few years of our marriage can’t have been easy for Ingeborg. At the university, my job as Rudolph Fleischmann’s assistant meant that I got involved in teaching experimental physics by being responsible for the preparation of experiments to be demonstrated during the main lectures. Because of this I sometimes had to stay late in the evening and my wife was waiting for me for dinner in vain.

Fig. 3.6

Herwig and Ingeborg’s wedding photo, taken in Hamburg on 14 March 1949 (Herwig Schopper’s personal collection. ©Herwig Schopper, All rights reserved)

Sometimes she came to the institute to find me, but in the evening the institute was locked so she would call to me from the street outside. This turned out not to be such a good idea, since next to the institute there was the main court of Hamburg, complete with a prison wing to hold delinquents under trial. When my wife tried to call to me, the prison guards thought she was trying, illegally, to contact a prisoner. If that was not enough, barely a year or so into our marriage, I had an opportunity that I could not refuse to go and work with Lise Meitner for a year in Stockholm. Travel was still very much restricted, and the offer was for me only, so Ingeborg had to stay home while I seized the opportunity (see Chap. 5, A sojourn in Stockholm with Lise Meitner).”