Otto Hahn (1879 - 1968)

The Man Whose Name We Chose for Our Grammar School - Founder of the Atomic Age

  • Otto Hahn:
  • 1904 Member of Ramsay's Laboratory at University College, London
  • 1905 Member of Rutherford's Laboratory at McGill University, Montreal
  • 1906 Member of Emil Fischer's Chemical Institute at Berlin University
  • 1912 Professorship
  • 1928 Director of the Kaiser Wilhelm Institute for Chemistry, Berlin
  • 1938 Discovery of nuclear fission together with Fritz Straßmann
  • 1944 Nobel Prize for Chemistry
  • 1946 President of the Max Planck Society

Childhood – Youth – Student Years

Otto Hahn was born in the German city of Frankfort/Main on March, 8th, 1879. His father, whose home town was Gundersheim, a small town near the city of Worms, was a journeyman training for the glazier trade. In 1875, at the end of his travelling years, he married widowed Charlotte Stutzmann, née Giese, from Frankfort. The couple had three sons: Heinrich (born in 1876), Julius (born in 1877) and Otto. Otto Hahn's father adopted his wife's son, Karl, who had been born to her in her first marriage.

Frankfort had experienced an exceptional boom, due to its annexation by Prussia in 1866 and to the foundation of the German Empire, ensuing the successful war against France in 1870/71. The fact that there was a building boom in its wake caused Otto's father's glazier's shop to grow into a real business soon; it ensured the family's high living standard and is known world-wide today. Karl and Otto enjoyed secondary education, their brothers Heinrich and Julius became glaziers. Heinrich continued his parents' business later, Julius opened a renowned art trade, Karl became a teacher of classical philology at a Frankfort grammar school.

Their brother Otto, however, began to study chemistry after taking his A levels in 1897, in spite of not having made good experiences with either the school subject of chemistry or physics during his school years at the "Klinger-Oberrealschule" in his home town. He later remembered: "In spite of all his effort our physics teacher did not succeed in making us interested in physics. The chemistry lessons were so boring that I was constantly afraid of falling asleep in the middle of the lessons, but nevertheless I became increasingly interested in that subject. My school leaving certificate sported three times 'full marks' but not, as one should think, in chemistry, mathematics and physics, but in physical education, music and religious education. He took chemistry as his first main subject, mineralogy as his second and the additional subject of crystallography at the university in Marburg, then one of the best in Germany. He reluctantly chose physics and mathematics as his minor subjects. Rarely was he to be found in those lectures. As he later confessed, he was never able to make up for what he missed that way. The seminar for advanced students of chemistry led by Professor Theodor Zincke he regarded as very instructive, however. After his second semester he took up studies in Munich for one year; among others he took lectures there with the well-known Adolf von Baeyer, who had succeeded in synthetically producing the much sought-after indigo. As Otto Hahn was also interested in art and the history of art, the Munich art galleries offered ample opportunities to him.

Having returned to Marburg in 1899, he began to write his doctoral thesis on organic chemistry, exactly speaking "On Bromine Derivatives of Isoeugenol". In October 1901 he submitted it to his academic teacher Professor Zincke and passed the examination for his doctorate with "Magna cum laude", which made him Dr. phil. Otto Hahn.

After serving in the army for one year with the 81st Infantry Regiment in Frankfort, he left the army, having reached the rank of 'vice sergeant'. In contrast to his brothers Otto Hahn did, however, not succeed in obtaining the rank of 'reserve officer', which was very desirable then for social reasons. As he himself later said, he had served without ambition: "You were a soldier because the Kaiser (the German emperor) and your Fatherland wanted you to".

Otto Hahn returned to Professor Zincke's chemical institute at Marburg where he obtained a post as an assistant and stayed there from October 1902 to October 1904. "Although I wasn't very skilful at performing experiments, the lectures went quite well nevertheless and Professor Zincke was satisfied", Otto Hahn stated in his memoirs, which once more proves that he was a very modest man. While assisting Professor Zincke, he especially learned to do scientific work systematically and with the utmost precision, which was to be of great use to him later in his nuclear research work and which he was famous for. At that time, however, he did not want to become a scientist yet. He intended to work in industry, in the field of organic chemistry, after having finished his time as Professor Zincke's scientific assistant. But the firm that was willing to take him on as a chemist wanted Hahn to know foreign languages. His teacher, Professor Zincke, advised him to go to England for some time. In October 1904 he went to London because Zincke had managed to find a job for his student with William Ramsay at the University College there.

Important sponsors: William Ramsay and Ernest Rutherford

When Otto Hahn came to him to London, famous William Ramsay had received the Nobel Prize for chemistry in 1904 for discovering the rare gases argon, helium, krypton, neon and xenon as well as for the analysis of the components of the atmospheric air. Meeting William Ramsay and working in his laboratory became decisive for Otto Hahn's further life. Ramsay's instructions for Hahn were: "You are going to work on radioactivity".

William Ramsay For Hahn, an organic chemist, this was surprising, as 'radioactivity' had not got anything to do with organic chemistry and was a very young field of research at that.

Strictly speaking, Wilhelm Roentgen had introduced an altogether new period of the natural sciences in 1895, when he had discovered the at first mysterious rays called 'X', which were named for him later. Only a few years before, the well-known Munich physicist Phillip von Jolly had advised young May Planck, who was to discover the quantum theory in 1900, against studying physics, "because everything had been investigated into already".

Ramsay had come across radium shortly before Hahn arrived in London. Madame Curie – one of Henri Becquerel's students – had isolated it from pitchblende in long experiments. The Polish woman, who was living in Paris then, proved with the help of radium that there are substances on the earth whose atoms split on their own initiative. Before that, on March 1st, 1896, Henri Becquerel had discovered the 'Becquerel rays' emitted from uranium salts, for which the term‚'radioactivity' was later coined. After the rare gases, those radioactive atoms were Ramsay's new field of interest now.

Together with Frederick Soddy, Ramsay tried to give experimental proof of the supposition that helium develops from radium. Hahn's task in this context was to extract 10 milligrams of radium from 100 grams of white barium salts by way of fractured crystallization – the method used by Madame Curie – and to determine the atomic weight of that element. Via complicated vaporization Hahn succeeded in isolating the desired radium from the barium salts. On this occasion he realized that in the preparation which he had supposed to be pure radium there had got to be other radio-active substances as well. With the help of his very fine measuring methods he found a new radioactive element in the end: radiothorium. Ramsay, very happy about this discovery, encouraged Hahn to go on researching into radioactivity: "Mr Hahn, you have discovered a new radioactive element. This is an excellent reference. Therefore you should stay with radioactivity. Go to Berlin. At the largest German university there will certainly be the possibility for you to continue your research work and to qualify as a university lecturer . . . But before that you should work for Ernest Rutherford in Montreal. Nowhere will you be able to learn more about radioactivity than at his institute."

Ernest Rutherford After the director of the chemical institute at Berlin University, Emil Fischer - like Ramsey winner of the Nobel Prize and Ramsay's friend – had agreed to employ Hahn later, Hahn applied for a job in Montreal. Rutherford said yes and around the middle of September 1905 Hahn sailed to Montreal to meet the most famous nuclear physicist of the time. While working at Rutherford's institute, Hahn discovered another hitherto unknown radioactive element: radioactinium. With Rutherford devoting his whole energy to his cherished project, alpha decay, Hahn was supposed to investigate into the nature of that phenomenon, too. He carried out research into the range of alpha rays and with Rutherford's advice he found out the proportion of charge to mass of the alpha particles. While working with Rutherford, Hahn also learnt how to construct electroscopes for measuring alpha and beta rays with the simplest of means, e.g. empty food or tobacco tins. Together with Rutherford he also used the complicated method of scintillation, which enabled them to see the alpha particles shining up in turn as small dots of light, and he was enthusiastic about it.

He finally found another product of radioactive decay while working at Rutherford's institute: thorium C. Rutherford's comment: "Hahn has a special nose for discovering new elements." Rutherford had taught him a lot. Hahn was devoted to him throughout his life – he was his shining example. Later the two of them became close friends. The months he spent in Montreal remained the best time of his life for Otto Hahn. In October 1906 he returned to Berlin.

Working with Lise Meitner
In his postdoctoral thesis which qualified him as a lecturer in Berlin with Emil Fischer, the renowned organic chemist and winner of the Nobel Prize in 1902, Hahn dealt again with the problems of radioactivity. Even though nobody in Fischer's institute knew anything about radioactivity then and chemists tended to look down upon this young field of research as a minor matter, Emil Fischer himself closely watched the progress of Hahn's research work. Hahn himself, as a young outside lecturer of chemistry, tried to get into contact with the physicists at his university. It was then that he came across Lise Meitner, an Austrian who had studied theoretical physics with Ludwig Boltzmann in Vienna. After Boltzmann's sudden death she wanted to continue her studies with Max Planck in Berlin. Only in the year 1908, when Prussia finally allowed women to study at university, could Lise Meitner move around the institute freely.

Soon afterwards Lise Meitner and Otto Hahn began to work together as the team they were to form during three decades. This period of Cupertino was only interrupted when Hahn had to serve in the German army in the First World War, where he went through the terrible experience of asphyxiating gas being used as a weapon of the war. The results of their common research work made both of them famous on an international level and brought them into contact with the world's most renowned scientists concerned with the research into radium: Marie Curie and Frederick Soddy, Enrico Fermi and, more often than once, Ernest Rutherford. In Berlin Hahn and Meitner used to work together well with Otto von Baeyer, James Franck and Gustav Hertz. When they succeeded in isolating radioactive products with a very short half-life, they would attach them to a piece of wire and quickly take them by car across Berlin to the Institute of Physics, were the above Berlin physicists were always prepared to help them with any kind of measuring. "We were young, happy and carefree – perhaps too carefree where politics were concerned", Lise Meitner remembered later.

When the Nazis came to power in 1933, Otto Hahn refused to become a member of Hitler's National Socialist Party. As a consequence he lost the leading position in his two institutes and gave up his lectureship at Berlin University. Lise Meitner, an Austrian Jew, was able to live in Berlin unhampered until March 1938. But this changed after the Nazis had annexed Austria. Now she was subject to German law. Helped by Otto Hahn – who gave her a diamond ring 'to use in any kind of emergency' – she managed to leave Germany secretly on the morning of July, 17th, 1938. She went to the Netherlands and from there she emigrated to Sweden and later to Cambridge in England.

The discovery of nuclear fission (1938)

Now Fritz Straßmann became the person Hahn co-operated with most successfully. Like Otto Hahn himself, Straßmann, too, was a meticulous and most energetic scientist. Like Hahn, Straßmann had also refused to join the National Socialist Party. Both research scientists now devoted themselves to elucidating Enrico Fermi's experiments with neutrons, who had bombarded the heaviest nuclei, those of uranium, with neutrons. In December 1938 Otto Hahn and Fritz Straßmann succeeded in splitting the nucleus of a uranium atom on a simple wooden experimenting table, which can still be seen at the 'Deutsche Museum' in Munich nowadays. Under the tabletop you can see several batteries attached, on top of the table there are Geiger counters, electronic amplifiers and a block of paraffin wax. This first nuclear fission took place in Berlin-Dahlem, in the 'Kaiser-Wilhelm-Institute' of Chemistry.

Hahn, who was known for having the profoundest experience in separating chemical elements, repeatedly hit upon what he supposed to be artificial "radium", which could not be separated from barium that was attached to it. Nevertheless he did not really believe in something like artificial "radium", because if radium isotopes were specially added, they could be separated from the carrier substance barium. But when working with uranium that had been bombarded with neutrons this separation did not work. Lise Meitner had to help with that. On December, 19th, 1938 Otto Hahn wrote her the memorable letter which was to become famous later. "There is something the matter with the radium isotopes which is so strange that we want to tell nobody but you at the moment . . . More and more we arrive at the terrible conclusion: our ra(-dium)-isotopes do not react like ra(-dium) but like ba(-rium). . . Perhaps you can suggest some fantastic kind of explanation . . . "

Even before Lise Meitner answered this letter, Straßmann was convinced: "We have undoubtedly found barium." On January, 3rd, 1939, Lise Meitner's answer arrived: "I'm rather sure now that you have really got barium as the result of the fission you have carried out and I regard this as a wonderful result on which I congratulate you and Straßmann from the bottom of my heart."

In January/February 1939, after renewed profound measuring, there was no doubt left: the uranium nucleus with the proton number 92 had been split into two nuclei of average mass – barium (with the proton number 56) and krypton (proton number 36). The formula for this was:
92U + 0n --> 56Ba + 36Kr (+ energy).

Both nuclei had a large surplus of neutrons, which was balanced firstly via ß-decay and secondly by the emission of surplus neutrons. This additional emission of neutrons, however, made chain reaction possible and thus the practical, technological use of atomic energy.

The atomic age had begun.

The disastrous consequence – the atom bomb

. . . my need is sore.
Spirits that I've cited
My commands ignore . . .
(Goethe, The Sorcerer's Apprentice,
translation by Edwin Zeydel)


Nuclear physicists soon realized the tremendous source of energy that the splitting of the nucleus had placed into the hands of mankind – like the present to Danae in Greek mythology it could be used for the good or the bad of mankind. The amount of energy set free when splitting one cubic metre of uranium oxide U3O8, a press report said on August, 15th, 1939, would suffice to produce the amount of energy which the electric power stations all over the German 'Reich' generated within eleven years. Before that, on August, 2nd, 1939, Albert Einstein, who had emigrated to the USA in 1933 already to escape persecution by the Nazis, had written the famous letter to President Roosevelt in which he recommended to enforce nuclear research, to stockpile uranium ore and to build an atom bomb: "A single bomb of this kind transported by ship or exploded in a port might perhaps be able to destroy the whole port and parts of the neighbouring areas."

Farmhall When this terrifying vision became reality on August 6th and 9th with the explosions of atomic bombs above Hiroshima and Nagasaki, the most important German nuclear scientists were interned at Farmhall, a manor house near Cambridge in England. They had been taken prisoners in Germany by the English and via several intermediate stops had been brought to Farmhall on July, 3rd, 1945. They were: Otto Hahn, Werner Heisenberg, Max von Laue, Carl Friedrich von Weizsaecker, Erich Bagge, Kurt Diebner, Paul Harteck, Horst Korsching, Karl Wirtz and Walther Gerlach, who was especially close to Otto Hahn and who was present to hold a speech when our grammar school celebrated its 50th anniversary in 1969 and on that occasion was named for Otto Hahn.

When Otto Hahn received the news of the first atom bomb being dropped on Hiroshima, he was aghast and full of despair. His friend, Max von Laue, who feared for Hahn's life, stayed with him during that night. Although Hahn had no part in the technological development of the atom bomb, this most awful consequence of his discovery was a hard blow to him. It was two of Max Born's former students, Robert Oppenheimer and Eduard Teller, who, unnoticed by the public and supported by a large staff, had developed the bomb. Max Born - a resolute opponent of atomic weapons – later said about those two students of his: "It feels good to have had such clever and diligent students but nevertheless I should wish them to be less clever than wise. Now mankind has been caught in an almost desperate situation due to their cleverness."

Now, after the atomic bomb had been dropped on Hiroshima, the German nuclear physicists at Farmhall were allowed for the first time to write letters to Germany. This showed that those nuclear scientists had been interned to make it impossible for them to produce atomic weapons before the Allies had got those weapons. Besides, this measure should prevent the Soviets, who had occupied part of Germany at the end of the war, from taking hold of the German nuclear scientists. It must be stressed, however, that the physicists who were held prisoners at Farmhall had never been engaged in producing nuclear weapons for Germany. Werner Heisenberg had led a uranium research team during the war, but its aim had been to develop a nuclear reactor. Otto Hahn was not a member of that team. As Hahn himself said: "We had no idea that atomic bombs had been built in America. We discussed about that a lot, and Professor Heisenberg, in the first place, tried to get hold of technical data. I was not interested that much. Being a chemist I have never really understood the details about the bomb, they were too complicated for me. . . . I would have declined at all costs to take part in building an atomic bomb."

On November, 16th, 1945 – still in British internment at Farmhall - Otto Hahn read in the 'Daily Telegraph' that he had belatedly been awarded the Nobel Prize for Chemistry in 1944 for his discovery of nuclear fission. The British authorities, however, did not allow Hahn to travel to Stockholm in December 1945 to take part in the presentation. His internment at Farmhall did not end before January, 3rd, 1946 when the nuclear scientists were taken back to Germany as free men.

The Nobel Prize Winner - His Commitment to the Fight Against Atomic Weapons

On returning to Germany Hahn first had to fight the accusations that were being spread by some important newspapers that the nuclear scientists interned at Farmhall had "supplied the Americans with the bomb". Then the question of which of the members of the Kaiser-Wilhelm-Institute for Chemistry was to become the new president of that society had to be answered. The then president, highly esteemed Professor Max Planck, the father of the quantum theory and Nobel prize winner in 1918, was 88 years old and because of his weak health no longer in a position to hold that post. He had lost his strength entirely when his son, Erwin Planck, who had worked for the Nazi regime as a secretary of state, had been executed on the grounds of having taken part in the bomb attack on Hitler on July 20th, 1944. This, together with Max Planck's incessant, quiet and private resistance to the Nazis, had caused his powers to fail altogether finally. Max Planck himself suggested Otto Hahn for the post of president of the Kaiser-Wilhelm-Institute. Hahn appeared to be exceptionally well-suited to that post because of his scientific esteem at home and abroad, his political impeccability, his position as the oldest scientific member of that society as well as his pleasant personality. After the 'Kaiser-Wilhelm-Institute' had been renamed 'Max-Planck-Institute' it was first re-instated in Goettingen for the British-occupied zone of Germany on September 11th, 1946.

Nobel Prize At the beginning of December 1946, Otto Hahn could finally set out on his journey to Stockholm for the presentation of the Nobel Prize in Chemistry on December, 10th, "for his discovery of the fission of heavy nuclei". The lecture he held on that occasion on December 13th, 1946, contained his first serious warning against the dangers of the acquisition of nuclear weapons: "The energy of nuclear physical reactions has been placed into man's hands. Shall it be used to encourage free scientific knowledge, social development and the alleviation of living conditions or shall it be misused to destroy what mankind has created over thousands of years? The answer to this question should not be difficult to find."

Having returned to Goettingen, where the Max-Planck-Society had its headquarters, Hahn finally succeeded, after long negotiations, in being granted permission to establish that society throughout the Federal Republic of Germany. On February 26th and 27th, 1948, the official foundation ceremony took place in Goettingen. The 69-year-old Nobel Prize winner now devoted himself entirely to setting up scientific institutes all over the Federal Republic. In essays, radio speeches and lectures that aroused considerable public attention he kept on warning against the deadly potential of that dangerous radiation. In 1955 he organized an appeal of 16 Nobel Prize winners who were meeting in Lindau. It has become famous under the Name of 'Mainau Declaration' against the misuse of atomic energy.

Atomic Committee In 1950 Hahn was elected Vice President of the German Atomic Committee whose chairman was the then Minister of Atomic Affairs, Franz Josef Strauß. The year 1957 saw highly controversial arguments concerning the atomic rearmament of the Federal Republic between Hahn on the one side and German Chancellor Konrad Adenauer and Franz Josef Strauß, who held the office of Minister of the Defence, on the other. The scientists joined together in the section of nuclear physics had requested the minister in a joint declaration to declare publicly that the Federal Republic would neither produce nor store nuclear weapons. Should the Minister of the Defence decline their request, the scientists intended to make their letter public. Strauß was outraged and accused the scientists of not having any understanding for his attempts to strengthen Germany against the Soviet Union. On April 12th, 1957, a letter drafted by Carl Friedrich von Weizsaecker was in fact handed over to the German press. The elite of German nuclear scientists had signed this text, in which they resolutely warned against the development and use of so-called strategic atomic weapons. Those scientists were: Otto Hahn, Carl Friedrich von Weizsaecker, Fritz Bopp, Max Born, Rudolf Fleischmann, Walther Gerlach, Otto Haxel, Werner Heisenberg, Hans Kopfermann, Max von Laue, Heinz Maier-Leibnitz, who was present at our grammar school to give a speech when we celebrated its 75th anniversary, Josef Mattauch, Friedrich Adolf Paneth, Wolfgang Paul, Wolfgang Riezler, Fritz Straßmann, Wilhelm Walcher and Karl Wirtz.

Konrad Adenauer and Franz Josef Strauß were infuriated. Another declaration, drawn up in unison with Adenauer, was needed to restore the peace between the Federal Government and the nuclear scientists: "The nuclear scientists who have taken part in the conference want to underline that it was not their first aim to keep only the Federal Republic out of common disaster, but to take initiative in the defence against something that is threatening to ruin the world; they were of the opinion that it was their duty to begin with the state whose citizens they are."

All these were first steps on the long way to nuclear disarmament of the two super-powers, the USA and the USSR, which has really taken place during the past decade and whose first positive result was the Non-Proliferation Treaty (NPT) signed on July, 1st, 1968.

When, at the age of 81, Hahn handed over his office of President of the Max-Planck-Society to the Nobel Prize Winner in Chemistry, Adolf Butenandt, in May 1960, he could not foresee that there was still another great task in store for him: due to a traffic accident in France in August 1960, in which his son and his daughter-in-law lost their lives, he had to take over the education of his grandson, Dieter. The great scientist and man Otto Hahn did not refuse to meet this challenge, either.

His meticulous scientific way of working, his human greatness and his modesty, his perseverance and his powers of endurance, his courage, his personal and political integrity did and still do set an example. It is the fact that he really is a shining example that makes him seem so suitable for naming a grammar school for him. Otto Hahn died on July, 28th, 1968. He lies buried in the cemetery in Goettingen among the important members of his "trade", Max Planck, Walter Nernst and Max von Laue. Let us honour his memory.

by Dr. Edmund Neubauer


Bibliographical Reference:

Baumer, F., Otto Hahn, Köpfe des XX. Jahrhunderts, Bd. 78, Berlin, 1974.
Gerlach, W., Hahn, D., Otto Hahn. Ein Forscherleben unserer Zeit (Große Naturforscher Bd. 45), Stuttgart, 1984.
Hahn, O., Mein Leben, Munich, 1968.
Hoffmann, K., Schuld und Verantwortung. Otto Hahn, Konflikte eines Wissenschaftlers, Berlin/Heidelberg, 1993.
Stolz, W., Otto Hahn/Lise Meitner (Biographien hervorragender Naturwissenschaftler, Techniker und Mediziner Bd. 64), Leipzig 1989.

This essay was first published in the commemorative publication "75 Jahre Otto-Hahn-Gymnasium Marktredwitz" (1994).

English translation by Brigitte Hippmann.

 

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