# Otto Hahn

Otto Hahn, 1938
Postage stamp from the Deutsche Bundespost, "Nuclear fission of the uranium atom", 1979

Otto Emil Hahn, OBE (born March 8, 1879 in Frankfurt am Main , † July 28, 1968 in Göttingen ) was a German chemist and a pioneer in radiochemistry . Between 1905 and 1921 he discovered numerous isotopes (now called nuclides ), in 1909 radioactive recoil , in 1917 the element protactinium and in 1921 the nuclear isomerism of "uranium Z". For the discovery and the radiochemical proof of the nuclear fission of uranium (late 1938) and thorium (early 1939) he was awarded the Nobel Prize in Chemistry of 1944 in 1945 .

Hahn is considered the "father of nuclear chemistry " and is one of the most important natural scientists of the 20th century.

From 1912 Hahn was a scientific member and from 1928 to 1946 director of the Kaiser Wilhelm Institute for Chemistry (KWI) in Berlin, and from 1928 to 1936 Senator of the Kaiser Wilhelm Society (KWG). In the time of National Socialism , Hahn was, according to Einstein's judgment, one of the “few who stayed upright and did their best during these evil years”. At the beginning of 1934, Hahn announced his resignation from the teaching staff of the University of Berlin in solidarity with dismissed Jewish colleagues . From 1946 to 1948 Hahn was the last president of the KWG and founder and from 1948 to 1960 the first president of the Max Planck Society for the Advancement of Science, which emerged from the KWG . Since the atomic bombs were dropped on Hiroshima and Nagasaki in August 1945, he has been one of the sharpest critics of the nuclear armament of the great powers and the progressive radioactive contamination of the earth due to uncontrolled nuclear tests . In contrast, he repeatedly advocated the peaceful use of nuclear energy. After the Second World War, Otto Hahn became one of the most respected personalities in Europe and also one of the most influential champions for global understanding and international détente , who was nominated several times for the Nobel Peace Prize for his active pacifism from 1957 onwards .

## Life

### childhood

Otto Hahn was born on March 8, 1879 as the youngest son of the master glazier and entrepreneur Heinrich Hahn (1845–1922, "Glasbau Hahn") and his wife Charlotte Hahn, née Hahn. Giese (1845–1906) born in Frankfurt am Main . He lived a sheltered childhood together with his brothers Karl, Heiner and Julius. Walther Gerlach writes in his biographical analysis:

“The first youth and school years were determined by the simple, solid circumstances of the parental home, the professional ambition of the father and the intellectual interests of the mother. The 9-year-old stepbrother Karl, who attended Goethe-Gymnasium and later became a well-known Frankfurt schoolboy as a classical philologist, had a major influence on Otto's upbringing. [...] All other interests during his school days such as literature, music, hiking, gymnastics, theater were neither superficial nor particularly deep - except for one that determined his thinking up into old age. Occult phenomena, spiritism , had interested and fascinated him. But what he read and thought about in the then fairly common writings worried him so much that he resolutely put an end to it. It is the only example I know of an independent critical impulse of the youthful spirit. 'Typical for Hahn' would be said by someone who only knows his later position on such problems. But this is based on that youth experience. Because from it developed his lifelong rejection of all speculation , of all hypotheses that were not based on clear facts . […] His memory was indeed unusual and remained with him into old age - an essential factor for the nature and success of his later research. "

At the age of about 15 Hahn began to be particularly interested in chemistry and, together with a schoolmate, undertook simple chemical experiments in his mother's laundry room.

“I learned how to make hydrogen, burn coal with oxygen, and experiment with sodium metal, yellow phosphorus and potassium chlorate. However, we have not yet dared to approach formula equations. Things got a little better in the higher grades. A friend of my older brother Karl, who studied chemistry himself, gave me the textbook The School of Chemistry by Stöckhardt , and in the senior class we even heard a course on organic dyes from Martin Freund , who later became professor of chemistry at Frankfurt University. He showed us very nice color reactions. So my desire to become a chemist slowly intensified. "

The father, who came to prosperity through innovative ideas, diligence and thrift, would have liked to see Otto Hahn as an architect, as he had built or acquired several residential and commercial buildings. But he was convinced that his son Otto intended to pursue a career as an industrial chemist.

### Studied in Marburg and Munich

After graduating from the Klinger- Oberrealschule in Frankfurt am Main, Hahn began studying chemistry and mineralogy with Theodor Zincke at the Philipps University of Marburg in 1897, with a minor in physics with Franz Melde and philosophy with the neo-Kantians Hermann Cohen and Paul Natorp , which should have a decisive influence on his already empirically shaped scientific thinking and acting. Since his father refused to join a fraternity, Hahn became a member of the 'Natural Science and Medicine Association of Students' in Marburg , a student fraternity that was not a beating at the time and forerunner of today's Nibelungia country team .

“The non- color association had transformed into the color-bearing association 'Nibelungia'. Suddenly and actually without any involvement, I was the 'old man' of a beating association, without ever having fought a racket. […] After January 30, 1933, the 'Nibelungia', like all student associations, included the 'Aryan Paragraph' in its statutes, which deleted all non-Aryan members, whether they were active or old men, from their lists. After the oath of eternal loyalty a few years earlier, I no longer considered my membership to be sustainable. I declared my resignation from the federal government and even after 1945 I could not make up my mind to rejoin. "

Hahn spent the third and fourth semesters with Adolf von Baeyer at the University of Munich , where, stimulated by visits to the Alte Pinakothek , he also devoted himself to art history with growing interest . In July 1901 he received his doctorate in Marburg magna cum laude under Theodor Zincke with a dissertation on "Bromderivate des Isoeugenol", a topic from classical organic chemistry . After completing his one-year military service in the infantry regiment Landgrave Friedrich I. von Hessen-Cassel (1st Kurhessisches) No. 81 in Frankfurt am Main, the young chemist decided to go to the university for two years as an assistant to his doctoral supervisor, Privy Councilor Theodor Zincke To return to Marburg.

### Early successes in London and Montreal (1904–1906)

Sir William Ramsay in his laboratory, University College London
Ernest Rutherford in the McGill University physics laboratory, Montreal 1905

Hahn wanted to work in industry. For this reason, and to improve his language skills, he moved in 1904 on the recommendation Zincke of the University College London and was an employee of Sir William Ramsay , the famous explorer of the noble gases . Here Hahn dealt with the then still young field of radiochemistry . While working with salts of the element radium , Hahn discovered the "radiothorium" in 1905, a new radioactive chemical element according to the ideas of the time. Ramsay was enthusiastic and introduced Hahn to the scientific community of London and the Royal Society , where he could explain his discovery in a lecture and then publish it in the Proceedings of the Royal Society . Apart from the dissertation, it is the first of over 250 scientific publications. On March 8th, a comprehensive report on 'A new Element' appeared in a London newspaper, the Daily Telegraph . In fact, the radiothorium was an isotope of the already known element thorium , 228 Th , which was still unknown at the time . The terms isotopy and isotope were not coined by Frederick Soddy until 1913 and became established internationally.

“Earlier I mentioned the curious historical fact that no one consciously repeated the work Madame Curie did on uranium minerals on thorium minerals. This was accidentally done by the now world famous Professor Hahn in 1905 in the laboratory of Sir William Ramsay in London, during his very first investigation in the field in which he has shown himself to be the greatest living authority. He immediately discovered the "radiothorium", a new alpha emitter of the thorium series with an average life of 3 years. Of course, many other chemists also tried to obtain this new thorium member from thorium compounds, because it would have been very valuable just like radium. But they all experienced total failure. But how did the magician Hahn manage it, who at that time was still a complete beginner in the field of radiochemistry? "

- Frederick Soddy (1952)

In the fall of 1905, Hahn moved to the McDonald Physics Building at McGill University in Montreal , Canada , on Ramsay's recommendation, to deepen his knowledge with Ernest Rutherford. Here Hahn learned, among other things, the analysis of alpha rays, the measurement of gas ionization, the range and the electromagnetic deflection, and with these new methods he was able to use the ( according to the terminology at the time ) radioactive chemical elements thorium C (today: the polonium isotope 212 Po) and radium D. (the lead isotope 210 Pb) and radioactinium (the thorium isotope 227 Th) discover what led Rutherford to comment: "Hahn has a special nose for discovering new elements."

Together with Ernest Rutherford, Otto Hahn published two papers on the alpha rays of radiothorium and on the mass of alpha particles of thorium in Philosophical Magazine , the  leading scientific journal at the time - together with the British Nature .

### Research in Berlin (1906–1944)

Memorial plaque on the former Chemical Institute of the University of Berlin, Hessische Strasse, Berlin-Mitte
Otto Hahn and Lise Meitner in the laboratory, KWI for Chemistry, Berlin, 1913

#### Discovery of the Mesothorium (Radium 228)

In the summer of 1906 he returned to Germany and worked at the I. Chemical Institute of the Friedrich-Wilhelms-Universität Berlin with Emil Fischer , who provided Hahn with a “wood workshop” in the Chemical Institute as his own laboratory. There Hahn discovered in a few months - with extremely primitive equipment - the mesothorium I, the mesothorium II and - independently of Boltwood  - the parent substance of radium, the ionium. Mesothorium I (the radium isotope 228 Ra) became very important in the years that followed, as it - similar to Curie's radium isotope 226 Ra - was ideally suited for medical radiation therapy, with the great advantage that it was only half the cost to manufacture. For the discovery of mesothorium I, which at the time was also known as "German radium" , Otto Hahn was first proposed in 1914 by Adolf von Baeyer for the Nobel Prize in Chemistry.

In June 1907 Hahn completed his habilitation at the Friedrich Wilhelms University in Berlin . On September 28, 1907, at the Physics Institute under Heinrich Rubens, he met the physicist Lise Meitner , who was almost the same age and had moved from Vienna to Berlin. This is where the 30 year long collaboration and lifelong close friendship between the two scientists began. The essay on the absorption of beta rays from some radio elements , published in May 1908 in the Physikalische Zeitschrift , is the first joint publication (of a total of 50), and a short time later Hahn and Meitner published the discovery of a new short-lived product of actinium, actinium C.

After the physicist Harriet Brooks observed the radioactive recoil for the first time in 1904 , but interpreted it incorrectly, it was not until 1908/09 that Otto Hahn was able to demonstrate the recoil during the conversion and to interpret it correctly. Otto Hahn puts it this way: ${\ displaystyle \ alpha -}$

“As is well known, the decay of a radioactive atom happens explosively, the alpha rays reach a speed of up to 1/10, the electrons almost full speed of light. If such a radioactive atom bursts, the remaining atom will get a recoil from the ejection of the electrons or even more the alpha rays, similar to the cannon when the projectile leaves the barrel. The speed of the rest of the atom is therefore determined by the law of the center of gravity.

The physicist Walther Gerlach commented in retrospect:

“... a fundamental, significant physical discovery with far-reaching consequences for the further clarification of the radioactive conversion. - The radioactive recoil not only provided the proof that for the radioactive decay process, which at that time was in principle still incomprehensible (we didn't know anything about an atomic nucleus!), Which Hahn now so vividly calls an 'atom bursting', the mechanical principles of energy and Impulse apply. "

In the period that followed, Hahn and Meitner discovered several new radioactive substances using their newly developed "recoil method", including the isotopes 214 Po, 207 Tl, 208 Tl and 210 Tl.

From September 13 to 15, 1910, Hahn took part in the “1. International Radium Congress ”in Brussels and became a member of the newly established“ Radium Standard Commission ”together with Bertram B. Boltwood , Marie Curie , Stefan Meyer , Ernest Rutherford and Frederick Soddy . At the end of March 1912 the commission met again, this time in Paris, in the institute and in the apartment of Marie Curie, who had made a standard radium preparation from the purest anhydrous chloride. Lise Meitner wrote to Hahn, who was then still in Switzerland:

“I'm curious what you will tell about Paris. You shouldn't be annoyed that you have so many things to do, you're not famous for nothing. "

On October 10, 1910, Otto Hahn was awarded the title of "professor" by the Prussian state government "in consideration of his scientific achievements worthy of recognition", but it was not until 1919 that Hahn was given a lectureship in radioactivity at Berlin University.

In 1912 Hahn was appointed head of the radiochemical department in the newly created Kaiser Wilhelm Institute (KWI) for Chemistry in Berlin-Dahlem (today “Hahn-Meitner-Bau” of the Free University of Berlin , Thielallee 63). As the successor to Alfred Stock , he was director of the Kaiser Wilhelm Institute for Chemistry from 1928 to 1946, which he had been acting provisionally headed since 1926. Hahn was appointed a full member of the Prussian Academy of Sciences in Berlin as early as 1924 (at the suggestion of Albert Einstein , Fritz Haber , Max Planck , Wilhelm Schlenk and Max von Laue ).

Punta San Vigilio, painting by Curt Agthe (1862–1943)
Marble plaque by Massimo Ragnolini in memory of the honeymoon, unveiled in 1983 by Count Guglielmo Guarienti in San Vigilio

#### Wedding with Edith Junghans

After Otto Hahn met the 23-year-old art student Edith Junghans at a meeting of the Association of German Chemists in Stettin in June 1911 on a steamboat trip to the Baltic Sea , the couple married on March 22, 1913 in Edith's native city of Stettin, where their father, Counselor Paul Ferdinand Junghans (1859–1915), President of the city parliament until his untimely death in 1915. The young couple's honeymoon initially took them to South Tyrol and Bolzano . Otto Hahn writes in My Life:

“From Bozen we drove on to Lake Garda and stopped in San Vigilio on the quieter east side of the lake. We liked San Vigilio with its wonderful cypress avenue and the simple, pretty hotel so much that we decided to stay here and not go to Brioni as planned . When the last passenger steamer left the place in the evening, we were almost alone with a few painters.

My wife, who was a great swimmer, tried hard to get me excited about the water too. But it was so cold that I ran back to looking for solid ground. So instead we went for walks on the beautiful hills around San Vigilio and on the towering Monte Baldo . Occasional steamboat trips took us to places in the west and south that were already more popular with tourism. "

From the marriage in 1922, the future art historian and architecture researcher (at the Hertziana in Rome), Hanno Hahn, emerged as the only son, who died in an accident in 1960 with his wife and assistant Ilse Hahn on a study trip to France. They left behind a 14-year-old son, Dietrich Hahn . To commemorate Hanno and Ilse Hahn and to promote young talented art historians, the now internationally renowned Hanno and Ilse Hahn Prize was created in 1990 for outstanding services to Italian art history , which is awarded every two years by the Library of Trustees Hertziana in Rome.

#### First World War and discovery of the Protactinium

At the beginning of the First World War , Otto Hahn was called up for military service. From August to December 1914 he initially served as an officer’s deputy in two regiments on the Western Front , after which he became an officer ( lieutenant ) and member of the special unit for chemical warfare led by Fritz Haber (with James Franck , Gustav Hertz , Erwin Madelung , Wilhelm Westphal and Heinrich Wieland ). This developed, tested and produced poison gas for war purposes, trained the military in handling poison gas, prepared for use at the front and monitored the gas attacks. Besides Franck, Hahn was the only one who tested the gas masks and filters developed by the Haber's Institute in 1917, while wearing a gas mask in a hut filled with phosgene until the gas penetrated through the gas mask.

“Hahn was concerned at first, believing that the use of toxic gases in war violated the ' Hague Convention '. But he let Haber persuade him. The principle of duty and fulfillment of duties, which determines his personal and civic upbringing, and the so 'humane' justification that gas shortens war, thus preserves human lives - the unfortunate sentence that the end justifies the means - had its effect. 30 years later, when the same reasoning was used to justify the dropping of the atomic bombs in Japan, Otto Hahn suffered more than anyone else. "

- Walther Gerlach

Hahn served the gas regiment ( Pioneer Regiment 35 ) from January 1915 until the end of the war with only a few long interruptions. He was constantly commuting between the east, west and south fronts, Haber's Institute for Physical Chemistry in Berlin and the Bayer factory in Leverkusen.

For his military services Hahn received the Hessian Bravery Medal , both classes of the Iron Cross , the Albrecht Order with Swords and the Knight's Cross of the Royal House Order of Hohenzollern .

From December 1916 Hahn became a member of the ' Headquarters of His Majesty' in Berlin and was therefore able to devote more time to radium research at his institute between January and September 1917. In 1917 he isolated a long-lasting activity with Lise Meitner , they named the element "Proto-Actinium" and published their work in 1918 under the title The mother substance of actinium; a new long-lived radioactive element in the Physical Journal . In 1913 Fajans and Göhring isolated a short-lived activity from uranium (UX2) and named the element brevium . The two activities are different isotopes of the same element No. 91, which was finally named Protactinium by the IUPAC in 1949 and which Hahn and Meitner confirmed as the sole discoverers. As early as 1924 and 1925 they were proposed for their discovery by several colleagues for the Nobel Prize in Chemistry, including Max Bergmann , Viktor Moritz Goldschmidt and even Kasimir Fajans himself, who unencumberedly recognized the crucial publication by Hahn and Meitner.

#### Discovery of nuclear isomerism

In February 1921 Otto Hahn published the first communication about his discovery of uranium Z ( 234 Pa). It is the discovery of core isomerism that Walther Gerlach described in retrospect as follows:

“If Hahn escaped the discovery of the isotope because he did not dare to take the step from the experimentally demonstrable chemically indistinguishable to the extrapolated chemically identical , in 1921 he succeeded in a discovery that became very important for nuclear physics much later and was incomprehensible at the time: the nucleus -Isomerism. The word comes from general chemistry. Molecules that have the same atomic composition but differ in their properties due to different structures are called isomeric molecules. [...] Again, Hahn's discovery is based on the tenacious search for the cause of a slight deviation from normal. How he came to this discovery and how he ensured it against every objection was what Hahn considered his best work. "

It was not until 15 years later, in 1936, that the young Carl Friedrich von Weizsäcker succeeded in theoretically explaining the phenomenon of nuclear isomerism as the “metastable states of atomic nuclei”. For this discovery, too, the full significance of which was recognized by a few, Otto Hahn was nominated for the Nobel Prize in Chemistry several times from 1923 to 1929, among others by Bernhard Naunyn , Heinrich Goldschmidt and Max Planck .

Hahn's first monograph, What does radioactivity teach us about the history of the earth ?, which was published in 1926 by Springer-Verlag , became widely known, and which quickly became a standard work after its publication, and in which Hahn wrote the not yet generally recognized and controversial theory of continental drift of Alfred Wegener fully confirmed. A review in the natural sciences notes:

“The danger that unsaved hands would seize this delightful subject was very high. It has now been processed by the most qualified expert. [...] The book deals with three big problems of geology resp. geophysics, all three of which are given a new answer through research in the field of radioactivity: 1. the age of the solid earth's crust, 2. the heat balance of the earth, 3. the periodic surface changes in the solid earth's crust (mountain folds). In any case, this clearly written little book can be recommended to anyone who wants to find out more about the geo-physical significance of radioactive processes. "

Due to common geological interests , an extensive scientific, very friendly correspondence developed between Hahn and Fridtjof Nansen , who had dedicated his study of climate changes in historical and post-glacial times (Oslo 1926) to his death in 1930.

Bunsen conference on radioactivity, Münster 1932. From left: James Chadwick , Georg von Hevesy , Lili Geiger, Hans Geiger , Lise Meitner, Ernest Rutherford , Otto Hahn, Stefan Meyer , Karl Przibram .

In the 1920s, Otto Hahn created a new field of work: with the "emanation method" and "emanation ability" he developed, he founded "Applied Radiochemistry " to research general chemical and physical-chemical questions. Applied Radiochemistry is the title of his textbook, published in English (and later in Russian) in 1936 , which contains the lectures given by Hahn in 1933 during his visiting professorship at Cornell University in Ithaca , New York ( USA ). This publication had a significant impact on virtually all nuclear scientists in the 1930s and 1940s, particularly in the United States, Britain, France, and the Soviet Union.

Glenn T. Seaborg , the co-discoverer of numerous transuranic elements and then President of the United States Atomic Energy Commission , wrote in the 1966 foreword to the American edition of Hahn's scientific autobiography:

“In the mid-1930s, as well as in connection with our work with plutonium a few years later, I used his book 'Applied Radiochemistry' as my Bible. [...] I think it is fair to call Otto Hahn the father of radiochemistry and the modern nuclear chemistry that resulted from it . "

### The discovery of nuclear fission (1938)

Together with Lise Meitner and his assistant Fritz Straßmann , Hahn continued the research work that the Italian physicist Enrico Fermi had started in 1934 by bombarding uranium with neutrons . Until the end of 1938, all scientists believed that the elements with atomic numbers greater than 92 (the so-called transuranic elements ) are formed when uranium atoms are bombarded with neutrons. The chemist Ida Noddack was an exception . She anticipated the paradigm shift of 1938/39 by speculating in Angewandte Chemie (No. 47, year 1934):

"It is conceivable that when heavy nuclei are bombarded with neutrons, these nuclei disintegrate into several larger fragments, which are isotopes of known elements, but not neighbors of the irradiated elements."

But no physicist took up Noddack's hypothesis and checked it, not even Ida Noddack herself. The disintegration of heavy atomic nuclei into lighter elements was considered impossible.

Otto Hahn's pocket calendar, 1938
Experimental apparatus with which Otto Hahn and Fritz Strassmann discovered nuclear fission on December 17, 1938 in Berlin ( Deutsches Museum , Munich )

Hahn had kept his revered teacher and friend Ernest Rutherford up to date on the progress of the so-called Transuran work from the start and informed him of all progress. At the end of April 1935, Rutherford wrote to him:

“Thank you very much for your short lines and for sending me copies of your latest articles on the neutron transformations of uranium. The investigation of this point must have fallen exactly into your area, and I am sure that you had a lot of fun clarifying the nature of the conversion products. It is all very interesting and is now so fast that it is difficult to remember all the results achieved. "

It is a tragedy that Ernest Rutherford, who was always convinced that the utilization of nuclear energy would never become a reality, could no longer experience the great breakthrough of his student Otto Hahn. Rutherford died in Cambridge on October 19, 1937, at the age of 66, as a result of an operation, just fourteen months before nuclear fission was discovered.

On July 13, 1938, after Hahn's preparatory help and accompanied by the Dutch chemist Dirk Coster , Lise Meitner emigrated illegally from Berlin via the Netherlands to Sweden , since she had lost her Austrian citizenship when Austria was annexed to Germany in March 1938 and because of her Jewish descent was particularly endangered. She herself was far less aware of the impending danger than Hahn, who feared that Lise Meitner might very soon become a victim of Nazi racial ideology. The last night before her departure from Berlin, she spent in the Dahlem house of Edith and Otto Hahn, who gave her a valuable diamond ring, an heirloom from his mother, for urgent emergencies . Looking back, Hahn wrote:

“Coster himself only met her on the train; then they both left. The danger for Lise Meitner was the multiple checks by the SS on the trains going abroad . - We shivered whether she would get through or not. The agreed telegram came a day later, from which we gathered that Lise was in Holland. I will never forget July 13, 1938. "

Also in July 1938, Irène Joliot-Curie and Paul Savitch published the results of their research on transuranium elements, which they had carried out since 1937. Like Fermi, they irradiated uranium with neutrons; They registered an emitter with a half-life of 3.5 hours, but its chemical identification proved to be extremely difficult. Joliot-Curie and Savitch finally advocated the interpretation "that this body has the atomic number 93 and that the transuranic elements found by Hahn, Meitner and Straßmann so far are the elements 94 to 97." ${\ displaystyle \ beta ^ {-} -}$

When Otto Hahn and Fritz Straßmann looked for transuranium elements in a uranium sample irradiated with neutrons in December 1938, they found traces of the element barium . An organic barium salt from the Jewish chemist Wilhelm Traube , whose later arrest and murder Hahn tried in vain to prevent, served as evidence . On the basis of the decisive experiment on December 17, 1938 - the famous "radium-barium-mesothorium fractionation" - Otto Hahn concluded that the uranium nucleus had "burst" into medium-weight atomic nuclei. This was the discovery of nuclear fission .

"No one could analyze the temporal changes in the activity of several genetically related radionuclides in his head like him, and no one could match him in the skill and care of chemical operations with imponderably small amounts of substances, often only expressed as atomic numbers."

- Karl Erik Zimen

Hahn and Straßmann's radiochemical results were published in the journal Die Naturwissenschaften on January 6, 1939 , and provided irrefutable evidence (confirmed by calculations of the energies involved in the reaction) that the uranium had been split into smaller fragments made up of lighter elements .

In their second publication on February 10, 1939, in which they first used the term “uranium fission”, Hahn and Straßmann predicted that “several additional neutrons could be released” during the fission process - a process that was later described by Frédéric Joliot , Hans was confirmed experimentally by Halban and Lew Kowarski and verified as a " chain reaction ". On February 11, 1939 - Otto Hahn was the only one to inform Lise Meitner in advance of his radiochemical experiments without informing the physicists in his institute - Lise Meitner and her nephew Otto Robert Frisch, who had also emigrated to Sweden in the meantime, delivered a first theoretical one -physical explanation of nuclear fission in the English journal Nature . Frisch estimated the resulting energy at around 200 million electron volts and coined the term “nuclear fission”, which was subsequently recognized internationally.

Memorial plaque for the discovery of nuclear fission at the former KWI for Chemistry, unveiled in 1956

In a later tribute, Lise Meitner wrote :

“The discovery of nuclear fission by Otto Hahn and Fritz Straßmann opened a new era in human history. The scientific achievement on which this discovery is based seems so admirable to me because it was achieved purely chemically without any theoretical guidance. "

In an ARD interview (on March 8, 1959) she added:

“It succeeded with an unusually good chemistry from Hahn and Straßmann, with a fantastic chemistry that really nobody else could at that time. The Americans learned it later. But at that time Hahn and Straßmann were really the only ones who could do that because they were such good chemists. You have really demonstrated a physical process with chemistry, so to speak. "

In the same interview, Fritz Straßmann replied more precisely:

“Professor Meitner has stated that the success is due to chemistry. I have to correct them a little. Because chemistry has only managed to isolate the individual substances, but not an exact identification. To do this, Professor Hahn's method was necessary. So that's his merit. "

And in her article Otto Hahn - the discoverer of uranium fission (1955) Lise Meitner explicitly emphasized:

“Hahn is one of the founders of radiochemistry and as such has discovered a considerable number of new radioactive substances. With great ingenuity, he understood how to apply this to a variety of physical, chemical and geological problems. Ultimately, his greatest achievement, the discovery of uranium fission, for which he received the Nobel Prize, belongs in this direction of work.

Hahn's most momentous achievement is undoubtedly the discovery of the fission of uranium, which led to the development of an almost inexhaustible source of energy with very far-reaching uses - for good or bad. How much Hahn cares about the restriction to the peaceful use of atomic energy is evident from many of his speeches and lectures. "

The chemistry professors Hans-Joachim Born (Munich) and Fritz Straßmann (Mainz) also agreed again after Otto Hahn's death in 1968:

"The fact that, as a chemist, he succeeded in discovering the fission of heavy atomic nuclei was the fulfillment of a busy life and the culmination of tireless research."

Nevertheless, some historians close to theoretical physics have occasionally discussed controversially in recent times what part Lise Meitner played in the experimental radiochemical evidence of nuclear fission. For example, Ernst Peter Fischer , physicist and science historian at the University of Konstanz , even drastically described the fact that Lise Meitner did not receive a Nobel Prize as “the stupidity of the Swedish Academy”. Both Fritz Strassmann and Lise Meitner personally would have contradicted this simplistic assessment.

"That, in my view, is precisely the great moral value of scientific education, that we have to learn to be in awe of the truth, regardless of whether it agrees with our wishes or preconceived notions or not."

- Lise Meitner

The head of the Institute for Radium Research in Vienna, Berta Karlik , wrote to her colleague Erika Cremer :

"Since I followed the Berlin work closely at the time, and was so well known and even friends with Hahn as well as Meitner personally, I have always been of the opinion that the discovery of the split is solely due to Hahn."

And Otto Robert Frisch occasionally emphasized to prevent misunderstandings:

“This discovery, which was deservedly awarded the Nobel Prize in 1944, caused great excitement all over the world. [...] Otto Hahn called the process 'bursting', whereas today it is called 'splitting'. "

During the war, Otto Hahn - together with the employees Hans Joachim Born, Siegfried Flügge , Hans Götte, Walter Seelmann-Eggebert and Fritz Straßmann - worked on the fission reactions of uranium and compiled a list of proven 25 elements and 100 isotopes by 1945 astonishing performance under the working conditions severely restricted by the war.

### Tailfingen (1944-1945)

Villa Hakenmüller, Tailfingen, Panoramastraße 20

On the night of February 11-12, 1944, the Kaiser Wilhelm Institute for Chemistry was hit by a heavy bomb, so that constructive research work could hardly be continued. Otto Hahn wrote to his brother Heiner in Frankfurt am Main:

“My institute has hit the bull's eye, which has just exploded in my director's office. Half of the beautiful institute was completely destroyed. All my documents, reprints, manuscripts, correspondence etc. are atomized! Valuable and now unrecoverable equipment, which cost many thousands in peace, is gone. "

Hahn therefore decided to outsource his institute to southern Germany, which was largely spared from Allied bombing attacks. Three empty textile factories were found in Tailfingen (Württemberg) and the intact remains of the institute, in particular the highly active preparations and the beryllium neutron sources, were integrated into them. Otto Hahn and his wife moved into two rooms in the villa of the textile manufacturer Julius Hakenmüller at Panoramastrasse 20, where they stayed until the end of the war.

### Period of National Socialism (1933–1945)

Through his energetic and consistent demeanor towards the Nazi authorities, Otto Hahn, who was an opponent of the Nazi dictatorship from the beginning and repeatedly successfully opposed the invitation to join the NSDAP , together with his courageous wife Edith, was able to manage many endangered or persecuted institute members and private individuals and protect them from being deployed to the front or even from being deported to a concentration camp .

“During the war years he became the keeper of life for many. He was always ready to help and support when serious difficulties loomed. He only countered quickly finished things with a serious, ironic warning. "

- Hans Joachim Born and Fritz Strassmann

"The cases in which the Hahn couple helped oppressed and persecuted people are innumerable, openly and even more in secret, regardless of their own endangerment."

- Walther Gerlach

The Hahn couple, in particular Edith Hahn, also provided practical humanitarian survival aid for fellow citizens in hiding, as can be seen from a report:

“The Hahns were with us once, and Ms. Hahn said that she knew hundreds of Jews living illegally in Berlin, who were hidden in coal cellars and attics, but that they were slowly starving to death because they were given no ration cards, no meat stamps, no bread stamps . I must have been around 16 then, I think it was early 1943 or late 1942. And while Hahns and my parents were talking about it, also about the danger of air raids that illegally living Jews in Berlin always stay in the attics had to - because of the air raid shelter - I had the impression that something should be done and then I made a number of friends. We collected some of our own ration cards, some of which were not owned by others - of course we didn't get to know any of the recipients - instead I brought them to Frau Hahn in Lichterfelde, where the Hahns lived, and she had the distribution mechanism. "

In November 1933 Hahn refused to sign the confession of the German professors to Adolf Hitler and in early 1934 resigned from the teaching staff at Berlin University in protest against the dismissal of Jewish colleagues, including Lise Meitner , James Franck and Fritz Haber . In a letter to James Franck and his wife Ingrid, Edith Hahn wrote:

“And if I didn't want you so much, I could envy you (and it's really not just a phrase) that you are Jews and so have your right on your side, and we have the shame and the indelible, never again redeemable shame for all and all times! [...]

I bought the rest of the Voss in our Ullstein branch on Wednesday and sent it to all the people I don't think are completely lost because I think your letter should bring them to their senses, and I hope the whole world will respond . "

Max von Laue remembers his friend Otto Hahn in a letter:

“Our friendship had to pass the acid test only in 1933 and afterwards. We thought of Hitler and National Socialism ... the same. And we put what we thought into action whenever possible. How often have you, how often have I helped Jewish acquaintances and other persecuted people spiritually by visiting them or inviting them to our houses in defiance of all prohibitions. We also know how to remember practical support by making it easier for them to emigrate, mostly independently of one another. In the Prussian Academy, we were able to put the brownie through the bill several times, for example in elections. Compared to the extent of the horrific event, this meant little; Our influence was insufficient for anything else. In any case, it was your masterpiece when Lise Meitner, for whom we were all worried, managed to escape to Holland. "

The chemist Hans Götte, one of Hahn's employees at the KWI for Chemistry since 1935, who had made lasting contributions in particular when the institute was relocated to Tailfingen in 1944, wrote in a review:

“Otto Hahn had no relation to power. He did not care in the least to rule or organize, nor did the powerful arouse his admiration. Where, as in the Third Reich, power was abused, he turned against it with great personal courage. It should only be remembered that he personally helped his long-time colleague Lise Meitner to escape across the Dutch border. He provided Jewish fellow citizens in hiding with bread cards and other essential items. Even on minor occasions, he defended himself against the system. When a conference was to be held in Strasbourg in 1943, two SS men refused to allow one of his employees of Swedish nationality to enter Alsace. The otherwise so peaceful rooster - he could get very angry if it mattered - rushed to both of them with a raised voice so that they forgot their regulations and did not hinder the journey. "

In November 1944 Otto Hahn intervened "in the case of the Jew Maria Sara von Traubenberg, née Rosenfeld", as it was called in the Nazi terminology of the time. In a letter to SS-Hauptscharführer Dobberke Hahn wrote that “Dr. von Traubenberg was involved in the 'secret work on uranium' as a physicist and employee of her husband. Only she could overlook the important research results of her deceased husband. ”The Gestapo was deceived by Hahn's exaggerated but effective words and deported Maria von Traubenberg not to Auschwitz , but to Theresienstadt , where she was given a room of her own to house her husband's estate to edit. She was saved and survived. At the end of 1945 she left Germany and moved to relatives in England.

### Internment in England (1945)

At the end of the war, in April 1945, Otto Hahn was arrested by allied special units of the Alsos III mission in Tailfingen (today: Albstadt ) and, after brief stops in Reims , Versailles and Huy, with nine German physicists (including Max von Laue , Walther Gerlach , Werner Heisenberg and Carl Friedrich von Weizsäcker ) interned as part of Operation Epsilon in the Landhaus Farm Hall in Godmanchester near Cambridge (England). Walther Gerlach writes:

Hiroshima after the atomic bomb was dropped, August 6, 1945
The explosion: (mushroom cloud) over Nagasaki , August 9, 1945

“Everyone worked in the uranium association in one way or another on the development of a uranium reactor - except for Hahn himself and Max von Laue. - Why they were brought in was and remained as unclear as their status - whether captured, interned, in protective custody, secured: Hahn invented the word detainten as guests of His Majesty, at the pleasure of His Majesty , apart from Radio and newspapers were forced to live closed to the world. From the beginning he was naturally the doyen of the group; Quick grasp of a situation, clear judgment, humanity, humor, quick-wittedness and steadfastness, all registers were available to him for negotiations with the 'supervisors' and for resolving difficulties.

An assessment by the British security officers characterizes Hahn as benevolent and cooperative:

“A man of the world. He has proven to be the most helpful of all the professors, and his humor and common sense have saved the day on numerous occasions. He has a decidedly friendly attitude towards England and America. "

In Farmhall, the German scientists learned of the American atomic bombs being dropped on Hiroshima and Nagasaki on August 6th and 9th . Otto Hahn, who was first informed by the on-duty Major Terence H. Rittner, was on the verge of desperation and, as his companions reported, close to suicide, because as the discoverer of nuclear fission he felt jointly responsible for the death and suffering of hundreds of thousands of Japanese civilians .

Carl Friedrich von Weizsäcker recalls:

“Otto Hahn's reaction to Hiroshima was terrible. Because Hahn was a determined opponent of National Socialism from an early age. He was a good, classic liberal. He had placed all his hopes on a victory for the West, that is, for a victory for America. And now he learned that the people he had hoped for had developed this weapon and actually used it. That shook him.

This shock to Otto Hahn on the day of Hiroshima brought him a very big human closer to me, precisely because it was evident that he felt responsible for something that he was not responsible for according to any normal rule. Because Otto Hahn was a really moral and mature person, and so he felt that the dead of Hiroshima were on his conscience. And I adored him for this feeling. "

And Werner Heisenberg writes in his memoirs:

“Understandably, Otto Hahn was hit hardest. The fission of uranium was his most important scientific discovery, it had been the decisive and by no one foreseen step into atomic technology. And this step had now brought a terrible end to a big city and its population, unarmed people, most of whom felt innocent in the war. Hahn withdrew into his room, shaken and disturbed, and we were seriously worried that he might harm himself. "

During these difficult hours Hahn's active pacifism grew , which made him one of the most committed and important champions for peace, disarmament and international understanding in the years that followed.

The science historian Friedrich Herneck summarizes the essential points in a historical analysis:

“The fact that the insight gained by Hahn was initially not used for the benefit of mankind, but for its ruin, for the creation of means of mass destruction, can be ascribed to the political circumstances in which this discovery took place. The scholar is not to blame for this. But it is precisely through this tragic interlinking of science and society that Otto Hahn became a unique figure in world history, one of those natural scientists whose importance stands out beyond the area of ​​their specialist specialist area, such as - in another way - Galileo or Darwin. "

At the beginning of January 1946 the group of ten internees was allowed to return to Germany, and after a stay in Alswede (Westphalia), Hahn, Heisenberg and von Laue were released to the British zone in Göttingen .

### The Nobel Prize in Chemistry in 1944

Otto Hahn's Nobel Certificate
The concert hall in Stockholm , where the Nobel Prizes have been awarded since 1901

After Hahn was accepted as a foreign member of the Royal Swedish Academy in 1943 , it awarded him the Nobel Prize in Chemistry in 1944 - "for his discovery of the fission of heavy atomic nuclei," according to the official explanation. The academy waited until after the collapse of the Hitler dictatorship to make the announcement, otherwise Hahn would have been forced to reject the Nobel Prize. Therefore Hahn's election was not published until November 16, 1945. However, since he was still interned in England in December 1945, the prize could not be presented to him until December 10, 1946, by King Gustav V of Sweden in Stockholm.

Lise Meitner wrote to her friend Birgit Broomé Aminoff at the end of November 1945:

“Hahn has certainly fully earned the Nobel Prize in Chemistry, there is really no doubt about that. But I believe that Frisch and I have contributed something not insignificant to the elucidation of the uranium fission process - how it comes about and that it is connected with such a great development of energy was very far from Hahn. "

Carl Friedrich von Weizsäcker , Lise Meitner's former assistant, later added:

“Indeed, he deserved this Nobel Prize, would have deserved it, without having made this discovery. But that a Nobel Prize was due for nuclear fission, that was probably clear to everyone. "

Otto Robert Frisch wrote in 1956:

“In my opinion, that is quite correct. The discovery of the fission of uranium [...] was the decisive observation from which everything else had to develop very quickly. "

Walther Gerlach , experimental physicist, long-time eyewitness and one of the best experts on the historical context, emphasized in a later analysis:

“The suffering that Otto Hahn suffered as a result of Lise Meitner's expulsion from his institute and from Germany, the respect for people who, regardless of personal dangers, helped and alleviate need wherever they could, who were aware of all the hurts accepted the right path because a good conscience meant more to him in science and life than external recognition - all of this may have played a role in the award of the prize under unusual circumstances. But in the end it is the recognition of a researcher's life of rare fertility, the keystone of which directly changed science, world politics and the situation of mankind. "

And Elizabeth Rona , who had worked for Hahn at the KWI for chemistry from 1919 and had to emigrate in 1938, wrote in her memoirs:

"I have often thought that he deserved a second Nobel Prize - the Nobel Peace Prize."

Otto Hahn was proposed for the 1914 Nobel Prize in Chemistry for the first time by Adolf von Baeyer . By 1945 he was nominated a further 21 times (among others by Walther Nernst , Adolf Deismann, The Svedberg , Frans Jaeger, Wilhelm Palmaer and Arne Westgren ). Furthermore, Hahn was nominated for the Nobel Prize in Physics 16 times between 1937 and 1947, mostly together with Lise Meitner, but also with Fermi , Yukawa , Stern , Pauli and Bethe (among others by Werner Heisenberg , Max von Laue , Dirk Coster , Arthur H. Compton , James Franck , Samuel Goudsmit , Manne Siegbahn , Boris Iliin, Hendrik Kramers , Cyrias Quellet, Felix Bloch , Jean Thibaud and Louis de Broglie ).

### Göttingen: The founding of the Max Planck Society (1948)

At the beginning of 1947 the new news magazine Der Spiegel and its editor Rudolf Augstein managed to dispel some suspicions and rumors about Otto Hahn. The article states, among other things:

“Only after strict control and in 'escort' does the visitor - of course only this one - come to Professor Otto Hahn if he wants to visit him in his study. It requires English regulations for the site of the former aerodynamic research institute in Göttingen. Perhaps this fact was the starting point for that great talk a few weeks ago that the famous researcher and Nobel Prize winner could not move freely in Germany.

The office of the President of the Kaiser Wilhelm Society (which, despite all the plans, has not yet been closed) is anything but pompous. The fact that the atmosphere was quite cool was due to the lack of coal, and by no means to the people. Because Otto Hahn, the 68-year-old South German, knows no starry airs or scholarly vanities. He is a man of nobility and kindness. He has remained humble, focused on the essentials. Real anger has just gripped him. In all the interviews that Professor Hahn has given during these months, in all the statements he has made, he has used scientific arguments to counter the rumors that the secrets of the atom bomb had been betrayed to the Americans by the Germans. The atom bomb was a fruit of his discovery of uranium fission by neutrons, but never one he wanted or aimed at.

Mass stupidity, malice and know-it-all do not allow this truth to apply. Hahn is again suspected of having been "bought". Unfortunately, Germans are great at such denigrations. […] Professor Hahn only wants to be a man of science, a man who, according to his looks, could very well be a professional diplomat. And yet he has just completed an incredibly important political mission: He has brought the badly battered German name back to life. Of course, Hahn did not determine this himself, but previously unknown Germans and German-friendly circles in Sweden said it. That is the content of letters that were received in large numbers in Göttingen. [...]

One can understand it when the mentioned letter writers express their happy feelings about the fact that the German name was allowed to be pronounced again in front of the world. This is not Prof. Hahn's only impression of his stay in Sweden, but the decisive one: knowing that he was able to do his fatherland a great service. So the Nobel celebration became an event for Germany too. "

A week later, Erika Weisenborn, the sister of the writer Günther Weisenborn, published a letter to the editor in "Spiegel":

“How much sure tact is not part of awarding a German the Alfred Nobel Prize a year after the end of the war and choosing a man against whom no voice of protest was raised anywhere in the world. This act encourages the neutral Swedes. "

From 1948 to 1960 Otto Hahn was the founding president of the newly created Max Planck Society (MPG) for the promotion of science, which was able to regain the former reputation of the Kaiser Wilhelm Society through his work and his internationally respected personality.

“While he was still in England, he received a request from the aged Max Planck to take over the presidency of the Kaiser Wilhelm Society. In February 1946 Otto Hahn was given the difficult task of collecting the remains of the Kaiser Wilhelm Society that had been saved from the war in order to maintain the existence and organization of the society and to fill its institutes with scientific life again. Only a man of his size, his scientific reputation, his impeccable character and his kind nature, who was able to differentiate between guilt and error in each of his companions, could bring about the rebuilding of society under the name of Max Planck and a new beginning for German science and set a new goal. [...]

He was president for fourteen years, and when he resigned from office in 1960, the Max Planck Society again had 40 institutes and research centers, which offered 840 scientists job opportunities. The financing of the Max Planck Society was secured in the years of his presidency by the Königstein State Agreement of the states and by ongoing subsidies from the federal government. "

“After he took over the office, his innate kindness and the factuality of his thinking, far removed from any political prejudice, helped him over many negotiating difficulties. He was able to resolve tense situations with a joke, and he often won the hearts of even those who wanted to go other ways than himself. During the construction period, quick decisions were sometimes required. Hahn often made important decisions without asking any boards. He was happy when he succeeded. […] When rebuilding the Max Planck Society, he wanted to follow the image of the old Kaiser Wilhelm Institutes, which had ample equipment for the conditions of the time, but extremely modest compared to the needs of the new era . Hahn did not really enjoy the enormous expansion of the scientific enterprise, the inevitability of which he recognized, but which he was reluctant to cover with his name. All in all, he still enjoyed actively participating in the reconstruction, and at the end of his term of office he was proud of the Max Planck Society and the scientific life in its institutes that had come into being under his hands. "

- Werner Heisenberg

“As much as he worked with the widely visible and recognized success for the expansion of the institutes and the expansion of the MPG, he also emphatically emphasized that this society is only one member of the country's scientific activity. The Senate and Main Committee of the Research Association , of which Hahn was an active member for many years, owe him some advice and help. In his objectivity and altruism he went so far as to postpone the advocacy of donations to the MPG behind the financially worse off university institutes. [...]

Hahn headed the MPG as president until 1960. But even under his successor Adolf Butenandt he took part in the work of the society until he was the last year of his life: the appointment as “honorary president”, thanks to the society that owed its existence to him, was for him no jewelry, but an obligation. "

- Walther Gerlach

### Frankfurt am Main: Opening speech at ACHEMA IX (1950)

At the first "Exhibition for Chemical Apparatus" after the Second World War, ACHEMA  IX in July 1950 in Frankfurt am Main, Otto Hahn was invited to give the opening speech. His address with numerous historical examples and references, which he gave the title "Research and Technology - Freedom and Responsibility", culminated in the warning words:

“The ideal of the scientist has always been intellectual freedom, the pursuit of knowledge and the possibility of communicating it to like-minded people and enjoying success. Every coercion, be it private or state, leads to the stunting of research, and secrecy promotes the mistrust of the individual towards the individual, the distrust of the peoples against one another.

Unfortunately, it is the case that the spiritual attitude of mankind, their responsibility and their compassion for their fellow human beings have lagged far behind scientific and technical progress, so that this progress can be used against instead of for the relationships between people. Today science has undoubtedly become a political power factor of the first order. It should therefore be heard before political decisions that involve research results.

We should learn that even the greatest technical achievements, the greatest so-called 'proficiency', the belief that one can do anything if it only promises success, that this cannot be the right worldview . We must be in awe of human life again! "

### Fight against nuclear weapons and nuclear tests

Immediately after the Second World War , under the influence of the American atomic bombs being dropped on Hiroshima and Nagasaki , Hahn took a decisive stand against the use of nuclear energy for military purposes. He saw this kind of use of his scientific knowledge as abuse, even a crime. In the 1950s and 1960s, for example, he stepped up his engagement in numerous calls for disarmament, peace and international understanding, but without allowing himself to be absorbed by communist-driven initiatives. Hahn refused to accept him several times as a member of the World Peace Council founded by Frédéric Joliot-Curie just as strictly refused to participate in its various congresses or to sign pro-Soviet-oriented manifestos, such as B. in Warsaw in 1950, Stockholm in 1951, or in Vienna and East Berlin in 1952. Hahn explained his position in several letters to Frédéric Joliot-Curie, including at the beginning of February 1951, after moving from Joliot-Curie to the next meeting of the World Peace Council to the East -Berlin had been invited.

“I acknowledge with gratitude that you have taken the trouble to present the importance of this World Congress and the agenda in Berlin. I think you know me so well that you will believe me that I long for the avoidance of World War III as much as you do yourself, and that I keep thinking about what steps one could take to achieve this ideal goal reach. But, as I have already told you earlier, I consider the personal freedom of the individual and the freedom of entire peoples to be the most important thing in general, and I cannot imagine any general peace as bearable if this freedom without fear, without coercion and without prescribed opinion is no longer guaranteed. Surely this is also your own opinion. You write in your letter that this liberté de pensée is absolutely guaranteed at the World Congress. I am convinced that this will be the case, but I am not convinced that the gentlemen who live in the eastern zone of Germany would dare to express an opinion other than the one prescribed.

Time and again I experience that visitors from the eastern zone or from the Russian sector of Berlin, when they have the opportunity to speak to us alone without witnesses, speak very differently than they do in public, and one always has again the impression that the same dull pressure exerted on people at all such conferences as we experienced sufficiently during the Hitler era. [...]

Dear Professor Joliot, I am writing these few remarks so sincerely to you because I sometimes believe that you are in fact not sufficiently informed about the real freedom of conscience and belief in the East. We certainly don't live in an innocent paradise in the West either, but the opportunity to express your opinion, to publish it in independent newspapers, and even to slap it on the table if necessary, makes a lot of things easier.

I would very much appreciate it if we had the opportunity to talk in detail about all of these questions, but unfortunately the World Congress in Berlin is not the right place for it. "

#### Broadcast appeal: Cobalt 60 - danger or blessing for humanity? (1955)

Hahn's remarks became widely known in his radio speech on February 13, 1955 “Cobalt 60 - Danger or Blessing for Humanity?”, Which was published simultaneously in Germany, Denmark, Austria and Norway, and a few days later also in English translation via the BBC in London broadcast worldwide. In it he said among other things:

“A tremendous responsibility lies in the hands of political leaders today. Even if the ordinary atomic bombs , even if the hydrogen bombs only have localized but terrible effects there, then there is still the possibility of producing cobalt 60 with these hydrogen bombs. A mentally ill or power-obsessed dictator could then, following the example of 'après nous le déluge' , surrender the civilized world, but also his own country, to radiation death. Even without cobalt, the neutrons released in the explosion create dangerous radioactive dust particles that can be carried away over great distances. This possibility must never arise, and therefore the need for truly international control over the development of nuclear weapons, or rather, peaceful coexistence between peoples. [...]

A united appeal from all responsible scientists, who are aware of the dangers of using a weapon of war that threatens the world, should succeed in bringing those in charge of major politics on both sides of the Iron Curtain to a negotiating table.

Today war is no longer 'the continuation of politics by other means'. In a bombing war there is no longer a winner or a vanquished. The big bombs destroy the sites of civilization in an instant. The deadly radiations then do their work of destruction more slowly but comprehensively. Shouldn't the many opportunities for peace and prosperity of the peoples prevail if the people really know what it is about? "

The international positive response to this appeal, even from the Eastern Bloc countries , was used by Otto Hahn for numerous other actions with a comparable peace policy content.

Memorial in Berlin-Dahlem, in front of Hahn's former house (today Otto-Hahn-Platz), with the last sentence from the Mainau rally

#### Mainau rally (1955 and 1956)

Among other things, he was the initiator of the Mainau rally on July 15, 1955, in which initially 18 and one year later 52 Nobel Prize winners drew attention to the dangers of the atomic bomb and warned the countries of the world against the use of nuclear weapons of any kind . It says, among other things:

“We have gladly put our lives at the service of science. We believe it is a way to a happier life for people. We see with horror that this very science gives mankind the means to destroy itself. Full military use of the weapons possible today can contaminate the earth so strongly with radioactivity that whole countries and peoples would be destroyed. This death can hit the neutrals as well as the belligerent.

If a war broke out between the great powers, who could guarantee that it would not develop into such a deadly battle? So a nation that embarks on total war brings about its own doom and endangers the whole world.

We do not deny that perhaps peace is maintained today precisely through fear of these deadly weapons. Nevertheless, we consider it a self-delusion if governments should believe that they can avoid war for a long time by being afraid of these weapons. In extreme danger, no nation will refuse to use any weapon that scientific technology can produce.

All nations must decide to voluntarily renounce violence as a political last resort. If they are not ready for this, they will cease to exist. "

A few weeks earlier, Bertrand Russell had asked Otto Hahn whether he would be willing to sign a manifesto that he, Russell, had prepared to draw attention to the effects of nuclear weapons. This so-called Russell Einstein Manifesto was published on July 9, a few days before the Mainau rally , and was later widely known. Otto Hahn wrote in his notebook on July 12, 1955:

“The Russell call in the newspapers brings about the content of our manifesto. But because of the one-sided left tendency I had refused Russell to sign. "

In the same year Otto Hahn appealed in his speech at the general meeting of the Max Planck Society to the mutual understanding of the peoples:

“We urge the peoples of the earth and their statesmen to avoid the roads that lead to the destruction of our earth. First of all, this can hardly be done by a general ban on nuclear weapons. Even today, mutual possession of this weapon prevents its use. But the ways in which human tensions are discharged must fundamentally change. If we remain critical of our own convictions and are ready to understand the opponent's point of view, then perhaps the time will come when wars are prevented not by having a sufficiently large number of weapons of mass destruction, but by mutual understanding of the peoples, even if their ideologies are as different as those of East and West today. "

#### Göttingen Declaration of the 18 Atomic Researchers (1957)

A year later, Otto Hahn was one of the authors of the Göttingen Declaration , in which on April 12, 1957, together with 17 leading West German atomic scientists, he opposed the nuclear armament of the German Bundeswehr . The then Federal Defense Minister Franz Josef Strauss , who vigorously promoted nuclear armament, then made derogatory and insulting comments in front of journalists about Hahn ("An old fool who can't keep his tears and can't sleep at night when he thinks of Hiroshima!"). Federal Chancellor Konrad Adenauer defused the situation a few days later during a discussion with Otto Hahn and four leading scientists of the Göttingen Eighteen in the Chancellery.

The Göttingen Declaration found an unexpected response in public opinion , not only in Germany, but above all in the trade unions and at universities, where a strong student opposition leaned against it. Just a year later, the SPD , which also represented the position of the Göttingen 18 in the Bundestag , founded the Committee on Fight against Nuclear Death , which was also supported by the German Federation of Trade Unions .

The London weekly Observer came to the following conclusion in early June:

“Otto Hahn is a figure in world history. He is also a key figure in current German politics. But he has none of the attributes of the traditional heroes from the history books. […] This indefinable personal refinement, together with his old age, his great fame and the dignity of his position, give Otto Hahn an almost unique prestige in Germany and, in the spring of the Göttingen Declaration, gave it a tremendous impact on the German public. In the eyes of the Germans, Otto Hahn's signature probably weighed more heavily than that of the other 17 scientists put together, and not only because he is the great old man of German science, but because his decision embodied an act of conscience more vividly than any other . "

On June 28, during the Annual General Meeting of the Max Planck Society, Hahn again highlighted all of the key points in his speech:

“These eighteen have acted, each individually, aware of their special responsibility, based on their expertise. We did not expect that the appeal would have received such a strong response , especially from the Eastern Zone and the West German political opposition. It was clear to us that we had to get into a certain conflict with some West German government agencies. But we couldn't change it if we really finally had a serious discussion.

That is why we consider our current approach to be justified and we stand by it. We believe that we have done the world public a service. The numerous personal approvals, also from Western countries, confirm this. It now looks as if ideas about arms control are really gradually being seriously discussed, and during our conversation with the Federal Chancellor on April 17th we were deeply impressed by his concern about the arms race in the world and his hope for gradual disarmament .

It was an unbearable condition that the horrors of a hot nuclear war were painted on the wall again and again. If one side boasts that it can use super hydrogen bombs to melt the polar ice so that the continents are flooded, then the other side could have reminded them that dust of death with strontium 90 or cobalt 60 is falling over the hostile world and make all life there impossible for the long term.

Instead of this whipping up in fear, hopefully ways will now be found to initiate gradual relaxation, even at the risk of one side making a sacrifice without knowing how the other side will initially react to it. But we have to come to a gradual reduction in the arms race!

The constant continuation of the H attempts is, however, not very pleasant accompanying music. Hence the desire of the physicists to stop further attempts, which are repeatedly trumped by attempts by the other side. Hence our hope that smaller countries shouldn't make bombs. What can these be of use? You can only increase the risk that a bomb will suddenly explode and the global conflict will then begin.

I think I will agree with my colleagues in physics if I consider a truly international, non-party-dependent debate by leading experts from the United States and Europe, but also by Russian physicists, to be a very useful contribution to understanding ; first of all, this would be the place which could work out the methods of controlling armaments preparations, and such methods exist. With this we hope, or are even convinced, that we can do our governments a real service in their efforts towards gradual disarmament.

The Geneva Congress on the Peaceful Use of Atomic Energy two years ago was marked by friendly discussions between East and West. It opened the door to many of the previously kept secrets. Why not a congress of the same people for the peaceful reduction and perhaps prevention of an arms race that will no longer allow the world to rest?

I am not a politician, but I am not only speaking on behalf of the 18 nuclear physicists, but I am convinced that I am also speaking on behalf of the countless people who are unable to publicly express the pressure of their conscience. "

The Göttingen Declaration and all of the campaigns it initiated and influenced were ultimately successful, because the German Bundeswehr has remained nuclear weapons-free to this day , and it can hardly be assumed that this situation will change. Together with other members of the Göttingen Eighteen , he founded the Association of German Scientists (VDW eV) on October 1, 1959 during the conference of the German Physical Society.

#### Viennese appeal against A and H bomb experiments (1957)

On November 13, 1957, Otto Hahn's “Viennese appeal against the A and H bomb experiments” followed, and on December 28, 1957, his appeal on the Bulgarian radio in Sofia for an “urgent international détente and general nuclear disarmament”. Hahn closed both appeals with the imploring words:

"May the realization grow that with the possibility of the destruction of all earthly life that exists today, a great war is no longer the 'continuation of politics by other means'."

Among Hahn's listeners in Vienna was the writer Reinhold Schneider , who reported about it in his diary entries Winter in Vienna :

“I am constantly preoccupied with his destiny, his personality, as researchers, as rulers of time, have more to say to me than artists about the human being, about the fate of the spirit, about history. [...] Otto Hahn's lecture in the occupied concert hall is an attempt to account: a man whose destiny is questioning and finding came before being and not being in the world; research was not prepared to accept responsibility for history, its transition into history. Research can perhaps consolidate itself in a personal-ethical sense; its historical location is a surprising discovery and has not yet been explored. Even the genius works today in the quarry of power.

The bold attempt of a struggling conscience to document moral freedom is formidable, poignant. The audience feels that it is not a lecture, but an event. While they say thank you, the speaker, bent over a chair, carefully packs the blackboards that were used for his lecture in his portfolio. Power and impotence of the spirit, power and impotence of conscience, and thus: personality. "

On December 6, 1957, the GDR daily newspaper Neues Deutschland carried the following message:

“In an interview with the Copenhagen newspaper Politiken , the German atomic physicist Prof. Hahn expressed the hope that the 18 people from Göttingen will succeed in starting a broad international movement of scientists to fight the nuclear race. Prof. Hahn warned emphatically against the plans of the USA to set up nuclear missile bases in all western European NATO countries and to equip the armies of these countries with nuclear weapons. A 'little Hitler' could thus have the opportunity to plunge the whole of Europe into ruin. "

#### Petition by naturalists to the United Nations (UN) in New York (1958)

In January 1958 Otto Hahn and Albert Schweitzer signed the "Petition of Natural Scientists to the United Nations" prepared by Linus Pauling and later supported by over 9,000 scientists from 44 countries in New York for the "immediate conclusion of an international agreement on the worldwide cessation of nuclear weapons tests" and in October, together with the incumbent Pakistani President Ayub Khan , the former Prime Ministers Lord Clement Attlee , Edgar Faure , Tetsu Katayama and the Mayor of Hiroshima Shinzo Hamai u. a. the "agreement to convene an assembly to draft a world constitution". The petition states, among other things:

“An international agreement on the immediate cessation of nuclear tests would serve as a first step towards general disarmament and the final and complete abolition of nuclear weapons and avert the possibility of nuclear war that would spell catastrophe for all of humanity.

We share with our fellow human beings the great concern for the continued well-being of humanity. As scientists, we know the dangers that threaten us and we feel responsible for making these dangers known. We believe it is imperative that something is done immediately in order to reach an international agreement to end nuclear weapons tests. "

On May 31, 1958, the front page of the New York Times published a statement from its correspondent Harry Gilroy, headline “HAHN SEES ATOM SHORN OF TERROR - Pioneer Predicts Hydrogen Fusion Will Serve Peace Without Bomb's Peril,” in which Hahn “My own views on the future of fusion reactors ” . He later specified these views in a short biographical contribution:

“My particular wish for the future would be that the physicists succeed in achieving the controlled fusion of hydrogen into helium. Then one would have the possibility of extracting the artificial elements without using the uranium 235 contained in a nuclear reactor and without the plutonium produced in it, both of which provide the material for the atomic bombs. The heat of reaction of the fusion reactor could be used to generate electricity just like that of the uranium reactor. So one could imagine a world for the not at all distant future in which the inexhaustible abundance of water from the world's oceans would bring us all the blessings of modern atomic technology, which are currently still linked to uranium with its dangerous transformations. "

In the same year Hahn was awarded the " Hugo Grotius Medal with the Olive Branch" from the International Grotius Foundation in The Hague for "outstanding services to the spread of international law" .

#### Message to the 'Japanese Council against A- and H-Bombs' in Tokyo (1960)

At the end of January 1958 Otto Hahn was asked to join the Japan Council Against A and H Bombs and to be an honorary member. He accepted but had to cancel his participation in the first meeting of the Council. Hahn telegraphed the President of the Council, Koshiro Okakura:

“I send warm greetings to the Japan Council meeting on March 1st. Many of my German colleagues also fully understand the desire of the Japanese people to be freed from the effects of the atomic weapons tests on Eniwetok . That is why we, too, are in favor of stopping the experiments. I wish your conference a complete success. "

Hahn also sent a corresponding message to the Japan Council meeting in February 1959, which he specified again for the September 1960 meeting in Tokyo and which was read out by the chairman in his opening speech at the general meeting. Hahn's words were then published in several Japanese daily newspapers:

“As I have emphasized many times on official occasions and in my lectures, I consider the production of A- and H-bombs to be a great danger to humanity, especially when smaller states, one after the other, want to produce them too. It would be very welcome if the United States and Britain on the one hand, and the Soviet Union on the other, were to neutralize each other by owning these weapons. We have to negotiate an agreement with these nuclear weapons-producing nations, but even after this treaty I am a staunch opponent of the ever-increasing number of atomic bombs and I support everything that contributes to their elimination. I wish the Japan Council a complete success across the board. "

#### Moscow Treaty to Cease Nuclear Tests (1963)

On August 5, 1963, after the nuclear test ban decided in Moscow, the so-called "Moscow Treaty" between the Soviet Union, the USA and Great Britain came into force, Otto Hahn welcomed the agreement in a letter to ADN and pleaded for the Federal Republic of Germany to join soon:

In an interview with CTK, Prague, he added:

“I consider any conversation that can lead to a real relaxation between East and West as desirable. I therefore warmly welcome the cessation of nuclear weapons testing in the atmosphere, in the cosmos and under water. It has been proven that the ever increasing number of such tests also increases the radioactivity of the air and water. It is also well known that it has an adverse effect on human health that can even lead to serious hereditary damage. I consider every step to prevent this to be a good thing. "

Just two weeks later, on August 19, 1963, the Federal Republic of Germany acceded to the Moscow Treaty and immediately put Hahn's recommendation into practice.

Until his death he never tired of urgently warning in word and in writing about the dangers of the nuclear arms race of the great powers and radioactive contamination of the earth. Since 1957 Otto Hahn has been nominated several times for the Nobel Peace Prize by international organizations (including the largest French trade union CGT, the Confédération générale du travail ). The 1962 Nobel Peace Prize laureate Linus Pauling once described Otto Hahn as “one of my role models”.

“I have admired Otto Hahn since my early youth, the researcher and the person. Hahn's reason for his peace work was simply that he knew more about nuclear weapons than other citizens and therefore felt it was his duty to speak on this question, which is so crucial for humanity. He could explain, he had to use his knowledge. His knowledge for what? For an ancient human wish. Et in terra pax  - and peace on earth. That's how we read it in the New Testament. We hear it at one point in Beethoven's Missa Solemnis, in shocking tones. Thus, after the First World War, the League of Nations was created, which Immanuel Kant , the greatest of all philosophers, had already called for in his book On Eternal Peace (1795). So, after the Second World War, the United Nations was founded with the great hope of creating world peace. And so Otto Hahn, mindful of nuclear weapons, wrote about the need for world peace until shortly before his death . "

### The 1st UN Conference "Atoms for Peace" in Geneva (1955)

On December 17, 1954, Otto Hahn wrote in a letter to the President of the UN General Assembly , the former Dutch Foreign Minister Eelco van Kleffens :

“As I learned from American newspapers and also from Paris, the United Nations is planning a general debate in New York on the use of atomic energy for peace. This is a topic that interests the whole world and it is very welcome that the many inhibitions that have hitherto stood in the way of general international debate are gradually being relaxed.

My personal opinion is now that the conference could be given the greatest possible response by including a number of internationally recognized scientists at the meetings of the United Nations. I am thinking of personalities who on the one hand can be considered real experts, but also of others who care about the future moral and ethical possibilities of using atomic energy. "

In June 1955 Otto Hahn was asked by Foreign Minister Heinrich von Brentano to represent the Federal Republic of Germany at the first UN conference " Atoms for Peace " in Geneva and to lead the German delegation. On August 8, the twelve-day conference was opened in the presence of delegations from 73 nations, chaired by Homi Jehangir Bhabha .

“The Geneva Conference was an unforgettable experience for many. Hundreds of participants became aware for the first time of the deeper meaning of a discovery that had now been made 17 years ago and which had penetrated the worldview of our time with such terrible clarity through Hiroshima and Nagasaki. [...]

Lectures, the content of which was at times sensational, gave way to receptions and one-on-one discussions. The representatives of the nuclear powers competed with each other to divulge information that had previously been kept secret. The United Nations selected 450 of the total number of submissions for the oral presentation and discussion at the conference itself. [...]

The practical experience the German delegation had in their hands on the subject of the conference was extremely modest. Meanwhile, in the midst of the participants, sat the man who had just taken  the first, decisive step with regard to the motto of the conference -  Atoms for Peace - in 1938: Otto Hahn. He was certainly the very last one who, after the fission of the uranium , would have had the slightest idea of ​​using this new, still largely unmistakable power for war. [...]

With his sense of humor and his great human security, Otto Hahn quickly gained ground at the conference, which was of great benefit to the other members of the German delegation. We even went to the official Soviet reception, where we could bask in Hahn's scientific glory. However, this visit took place against the resistance of the representative of the Foreign Office , because the Federal Republic did not yet have diplomatic relations with Moscow. "

### Encounter with Jawaharlal Nehru (1956)

At the general meeting of the MPG in June 1956 in Stuttgart, Otto Hahn again complained that the state subsidies for the Max Planck Society repeatedly fell short of expectations. In his manuscript, which was sent to the press in advance, and which Hahn's address published in excerpts, are the conjuring words:

“I have the impression that our Ministers of Culture should have even more to assert themselves over the Ministers of Finance. We will spend billions on armaments in the next few years. Shouldn't it be possible to raise at least a few hundred million for research, science and schools? "

“We are all happy and grateful that he exists as he is, as he rules. [...] And that's why I am not afraid, by thanking and paying homage to him, to use a rather old-fashioned word that is in danger of freezing in the vocabulary of public and scientific discussion: He is a pure person, and that is , it seems to me, for the public, is for science, is for science policy, nothing small. "

On the occasion of the state visit of Indian Prime Minister Jawaharlal Nehru in mid-July 1956 Hahn was invited to Bonn by Heuss and Federal Chancellor Konrad Adenauer . Hahn noted in his notebook:

"13. July: Off to Bonn. In the evening at 9.30 p.m., Adenauer invited Nehru in tails. All diplomats and women, from Conant to Sorin . I get to know Nehru: serious man, no pathos. Very beautiful daughter Indira Gandhi .

July 14: 1 p.m .: Lunch at Heuss, a smaller group. As diplomats only those from the Commonwealth . Nice speech by Heuss, nice and serious speech by Nehru in English, which will be translated excellently in a moment. I'm moving to the Petersberg . There still lecture by Nehru in closed. Society for Foreign Policy: very impressive. Probably nothing for the German agitators. "

### "Atomium Speech" in Brussels (1958)

In March 1958 Otto Hahn received an invitation from the Belgian government to give a lecture on atomic energy at the first world exhibition after the Second World War, Expo 58 in Brussels . He said yes. - Before that he had a “conversation with Hübinger, Ministry of the Interior, about a lecture in Brussels. I promise not to get political, that is, not to talk about our rejection of nuclear weapons, only about peaceful international cooperation. "

The motto of the Brussels Expo was "Human progress through technological progress", and the new future technologies of nuclear power and space travel were presented to a broader public for the first time.

On June 18, Otto Hahn gave his so-called "Atomium Speech" (original title: Atomium - symbol of international cooperation in science ) in front of a large auditorium . In it he stated, among other things:

“The big exhibition, at which we Germans are also guests, shows us the ' Atomium ' as the main attraction . The marvel is the image of a single atom, enlarged billions of times. The facility is, so to speak, the symbol for the modern, immense area of atomic research . The early historical development was mostly tied to individual names. You could almost say that everyone knew everyone from literature. With the chain reaction , the uranium pile, the nuclear reactor , things changed. Approximately 40,000 jobs have been carried out in the United States since 1939 and are considered official jobs of the AEC . The corresponding number for the UK is 11,000 to 12,000. The number of papers published annually all over the world on scientific and technological questions of atomic nuclear energy can be given today as around 20,000. But the dimensions of the plants are getting bigger and bigger, the financial burden for the individual working group, indeed for a whole country, is getting too big, and so we are now gradually experiencing the transition from the individual country to the national community in nuclear science. Secrecy gives way to pronunciation, distrust to trust. [...]

I believe that we can take in what we learn and see about the atom at this exhibition as a triumph of true international research and enjoy it, because science is international, at least it should be, it should promote peace and serve the advancement of all humanity. "

Hahn received general approval for his factual, neutral, apolitical words, including from King Baudouin , who gave a reception and dinner in his honor, at which Hahn became political in a short speech and expressed his hope that " international atomic research should limit itself exclusively to peaceful applications and refrain from any cooperation in military developments ”.

### Trip to Israel (1959)

Edith and Otto Hahn, 1959

In November 1959, Otto Hahn visited with a delegation from the Max Planck Society, the biochemist Feodor Lynen , the nuclear physicist Wolfgang Gentner and Hahn's son Hanno belonged representing the humanities, on official mission, the first time Israel, notably the Weizmann Institute of Science to to make the first scientific contacts with Israeli colleagues - u. a. with Abba Eban , then President of the Institute and later Foreign Minister, as well as with Professors Yigael Yadin , Giulio Racah and Yehuda Hirshberg from the Hebrew University in Jerusalem. Even Vera Weizmann , the widow of the founder and first President of Israel Chaim Weizmann , was in Rehovot a meal and a reception in honor of Otto Hahn on which this gave a widely acclaimed speech. The appearance of Otto Hahn and his delegation, six years before the establishment of diplomatic relations, marked a turning point in the relationship between Israel and Germany and made a significant contribution to overcoming the deep rifts between the two states caused by the Holocaust and the Nazi crimes. Since 1989, this trip has been honored as a historic event in several memorial events in Israel and Germany - each in the presence of the then Federal President Richard von Weizsäcker and the President of the Weizmann Institute Haim Harari .

### South Africa (1965)

In 1965 Otto Hahn turned down the invitation of the South African government Verwoerd to inaugurate the country's first nuclear research center and the first nuclear reactor on the African continent (SAFARI 1) in Pelindaba near the capital Pretoria . He justified this decision by pointing out that it was “impossible for him to support the racist apartheid regime and the discrimination and oppression of the black population in any way”. When Miriam Makeba , who was awarded the Otto Hahn Peace Medal in South Africa in 2001 for her fight against apartheid and for her services to human rights , heard about it, she responded spontaneously with emotional recognition: “Oh, I would have loved him! A great man! He was really my brother! "

### Journey to the ČSSR (1966)

In July 1966 Otto Hahn visited the Czech city of Jáchymov , the former St. Joachimsthal, at the invitation of the local city administration , to take part in the unveiling of a monument in honor of the married couple Marie and Pierre Curie and to give a speech. It was his last trip abroad. In Jáchymov he also met František Běhounek , a student of Marie Curie, who at the time had undertaken experiments with Hahn's mesothorium I (radium 228).

“Otto Hahn left Göttingen on July 10th with some skepticism because he felt he belonged to a nation that had inflicted great suffering on the Czechoslovak people during the Nazi era. The government of his country also refused to establish diplomatic relations with the ČSSR. Hahn was all the more delighted with the extraordinarily hospitable reception. 'I have not yet recovered from the surprise of the friendly reception that I have met everywhere,' he told the Lidová Demokracie newspaper . 'In my opinion, face-to-face encounters of this kind are the best way to remove all misunderstandings and to create good relationships that are sure to lead to lasting peace.'

As a guest of the Czechoslovak Academy of Sciences , Otto Hahn accepted an invitation to Prague at the end of his trip . In a speech on the Czechoslovak radio, Hahn also commented on the relationship between the two countries. According to a contemporary report, Hahn demonstrated "an astonishing sense of real and ideal values ​​that can connect peoples with one another". Otto Hahn found words that would suit some politicians. "

At a meal, Hahn was presented with the "Honorary Key of the City of Prague" by Mayor Ludvík Cerný , as a thank you and in recognition of his tireless international peace work.

Walther Ottendorff-Simrock , the great-grandson of the poet and philologist Karl Simrock , met Hahn in Jáchymov and then accompanied him to Prague. In his book Encounters , he recalls:

“Otto Hahn lacked any tendency towards professional one-sidedness and human tightness, which one would easily attribute to his old age. He always surprises with his open-mindedness and versatile knowledge, also in the field of beautiful literature. A quarter of an hour in the evening in the shadow of the Wallenstein Palace will always linger in me . It was getting dark, the gas lamps flared. None of us could escape the magic of the “Golden City” with its soil soaked in history. Otto Hahn, who knows how to play so many instruments, is captured by this mood. Spontaneously he begins to recite from ' Wallenstein ', not just fragments from Schiller's poetry, but to our astonishment the entire monologue. 'Professor, how is this possible? How can you still rely on your memory so precisely today? ' Our surprised questions penetrate him. And with a slight smile he replies naturally: 'What I once learned at school, I kept everything.' - Perhaps one should have answered him with Schiller : 'Nature is in an eternal league with genius.' "

### death

In March 1968 the Belgian Nobel Peace Prize laureate Dominique Pire asked Hahn whether he would be willing to take over the protectorate for the Pavillon de la Paix planned for the 1970 World Exhibition in Osaka . Hahn initially had concerns about his old age, but since he held Père Pire in high esteem, and the latter assured him that he would not incur any administrative obligations, he finally agreed. Hahn ended his letter to Pire of March 18, 1968 - the last official letter - with the words:

"I should be very happy if your efforts would help to finally convince all peoples or their rulers of the need for world peace, so that in the not too distant future any danger of war will be averted."

Three days later Hahn was transferred to the “ Neu Mariahilf ” clinic in Göttingen due to an injury to his cervical spine, which he suffered from a fall while getting out of his company car , where he died of acute heart failure on July 28, 1968 after a four-month stay . Federal President Heinrich Lübke wrote in his condolence to Hahn's widow Edith Hahn:

“It is with deep sorrow that I remember your late husband, who was close to me like a friend. A richly gifted and blessed life is completed. Our German people and humanity say goodbye to a man who, through the strength of the spirit, through a high sense of responsibility, goodness of heart and unusual achievements, has become a role model for the creative work of scientists of our time. Through his life and work, the deceased is a shining example of that spirit and that disposition that does honor to the German name in the world. "

On July 29, the Max Planck Society published an obituary notice in all major newspapers:

“Our honorary president Otto Hahn passed away on July 28th at the age of 90. As the founder of the atomic age , he will go down in human history. With him Germany loses a scholar who was equally distinguished by his upright posture and inner modesty. The Max Planck Society mourns for its founder, who continued the tasks and tradition of the Kaiser Wilhelm Society after the war, and for a kind and loved one who will remain unforgettable to everyone who met him. His work will continue. We remember him with great gratitude and admiration. "

Hahn's death was accompanied by worldwide appreciation and sympathy. The cities of Frankfurt am Main and Göttingen , as well as the federal states of Lower Saxony and Berlin, flagged all public buildings at half-mast for three days .

On August 1 , the funeral service took place in the Göttingen University Church , St. Nikolai , and was attended by around 600 personalities from politics, science, business and culture, including the Federal President , the Federal Council President , the Prime Minister of Lower Saxony and several Federal Ministers as representatives of the Federal Government the grand coalition under Federal Chancellor Kurt Georg Kiesinger and Foreign Minister Willy Brandt , the mayors of Frankfurt am Main, Göttingen and Berlin, the presidents of numerous academies and universities, the ambassadors of Belgium, France, Greece, Great Britain, Sweden and the USA, two envoys of the Israeli government and the Weizmann Institute , as well as the Apostolic Nuncio Archbishop Corrado Bafile as a representative of Pope Paul VI. , also Max Born , Manfred Eigen , Walther Gerlach , Werner Heisenberg , Fritz Strassmann , Carl Friedrich von Weizsäcker and numerous scientists, bankers and industrialists who were friends with Hahn, among them Hermann Josef Abs , Clemens Plassmann and Karl Winnacker . The Second German Television broadcast the celebration unabridged in its evening program.

Regional Bishop Hanns Lilje gave the funeral sermon and MPG President Adolf Butenandt praised Hahn in his commemorative speech as “great in spirit”, “genius of science” and “immortal of humanity”.

Otto Hahn's grave in Göttingen

Walther Gerlach , Otto Hahn's friend, recalls: “On August 1st, friends and scientists from all over the world, the Federal President, the regional bishop and the entire population of Göttingen, took him to the grave of honor in the Göttingen cemetery next to Max Planck and Max von Laue. The simple tombstone only bears his name and the uranium fission formula. "

In an obituary in the Süddeutsche Zeitung, Werner Heisenberg wrote :

“The consequences of his most famous discovery have fundamentally reshaped the political and economic image of the world. Perhaps this discovery was more controversial in its implications than any other scientific advance before it. But if you think of Otto Hahn's personality, there was hardly ever a researcher who was so little controversial, so generally respected and loved as he was. Perhaps the deepest root of his outstanding human and scientific success was the fact that, despite all difficulties, he said 'yes' to life without reservation, and that he was able to transfer this happy yes to his colleagues and friends.

The great discovery of Otto Hahn will appear in much later times as the beginning of a completely new epoch in world history, in which natural science and technology, and the rational thinking behind them, dominated people's lives to an unprecedented extent - an epoch For the time being we can only hope with fear that it will be happier than the difficult past in which Otto Hahn worked with joy. "

His grave, in which Hahn's widow Edith, who died a short time later on August 14, was also buried, is located on the so-called Nobel Prize winners' roundabout in the Göttingen city cemetery , where Max Born , Walther Nernst , Max von Laue , Max Planck , Otto Wallach , Adolf Windaus and Richard Zsigmondy are buried.

Two weeks after Hahn's death, the Munich Bruckmann Verlag published his memoirs under the title “Mein Leben”, which received extremely positive reviews in numerous reviews, had five editions in just a few months, and two years later also in England, the British Commonwealth of Nations , the USA and Japan in licensed editions. For example, Arndt Rühle wrote in Münchner Merkur :

“What was praised about his grave: his genius, of course, but also his modesty, kindness, courage and dedication, that is all confirmed here in an unpretentious way. A very private, humorous and self-critical, but above all information-rich biography. And the rare stroke of luck: a light-handed, excitingly written contemporary document full of anecdotes, from childhood in Frankfurt, from studying in Marburg and Munich and his already spectacular scientific beginnings, to world-changing successes, always closely intertwined with political and private life . A history textbook of radiochemistry by the way. "

And Ernst H. Haux commented in the Berliner Tagesspiegel :

“And anyone who believed that the name Otto Hahn was only found in the annals of natural science with the key word 'nuclear fission' will recognize his own great mistake. With this epoch-making discovery, Hahn had to earn the later, false reputation of a 'grandfather of the atomic bomb' as well as his capture and internment as a quasi-war criminal in the first months after the war. His humble, benevolent nature forbade him ever to capitalize on his discovery. Only then did he go public when it came to standing up against injustice and inhumanity. His simple memories, which never lack humor, are an invaluable document of his and our time. "

## private interests

### Rockclimbing

The Matterhorn in the Valais Alps, which Otto Hahn climbed in 1911 over the Furggengrat
In the summer of 1930 Hahn, who is now 51 years old, climbed three four-thousand-meter peaks in the Bernese Alps, a. a. the Finsteraarhorn over the southern east wall rib.

Otto Hahn first sniffed alpine air in 1898 while climbing Germany's highest mountain, the Zugspitze , which was to establish his love for the mountains. Then there was initially a break of several years as a result of his studies and stays in London and Montreal.

“Finally, in 1907, already busy with his own research at the Chemical Institute of the University of Berlin, Otto Hahn's second life began, documented in black and white with an ID from those days: He became a member of the German-Austrian Alpine Club , Section Frankfurt am Main. In the same summer he celebrated a reunion with the mountains, and that in the Ötztalern up to the Wildspitze . In 1911, when the Kaiser Wilhelm Society was founded in Berlin, he was in Switzerland. The ascents of Matterhorn and Dent Blanche have been handed down from that year , from 1922 Großglockner and Kitzsteinhorn in the Tauern, 1930 Mönch , Jungfrau and Finsteraarhorn in the Bernese Alps. In 1927 he was with his wife on the Allalinhorn and in 1928 on the Three Peaks . With the greatest respect, as his most difficult undertaking, he often remembered the Südlenzspitze and the Nadelgrat in the Mischabel group near Saas-Fee .

Today we would say that Otto Hahn took everything that was good and what was expensive in sweat, whether in the Silvretta , in the Dolomites , or on skis in Davos, in the Valais or in the Wetterstein , in the Stubaiern or in the Ötztalern. […] Family and friends have passed down that he prepared his tours with the same care and thoroughness as his laboratory experiments. Biographer Ernst Berninger wrote about Hahn's alpine hobby: 'It was a matter of course for a person who worked so intensely that he sought balance during the holidays in an area in which he could pursue the set goals just as intensively, and which he kept doing Experience of achievement and success in difficult situations. '"

In 1966, the playwright Carl Zuckmayer , who had settled in Saas Fee since 1958, wrote to Hahn:

“How nice that you did the same tours in Saas Fee as I did. The Allalinhorn twice, both times from the Britanniahütte , because that, with the wall climbing and the ridge, is the much more interesting ascent route. I know nothing more beautiful in the world than this morning departure from the hut at two or three o'clock in the morning, and the lights of the first twilight and sunrise between 3000 and 4000 meters. Now I often see these spring lights from a distance, but that too is wonderful. "

Since 1980, mountaineering equipment from mountaineer Otto Hahn, a gift from his grandson Dietrich , has been in the collections of the Alpine Club Museum in Innsbruck .

### Pets

Otto and Edith Hahn always had several cats in their Dahlem villa at Altensteinstrasse 48, including 'Muzie', about whom their son Hanno published a story in 1939 in the specialist journal 'Our Cat' , and a French shepherd, a Briard named 'Tommy'. There was also a terrarium in the house with a tree frog , called 'Möppi', for which Hahn liked to catch flies in his spare time, which he found a pleasant relaxation . At the KWI, too, younger employees were occasionally asked to catch “fresh flies”, as an authentic anecdote shows:

"Otto Hahn in dialogue with a young laboratory assistant: 'Did you catch the flies outside of your working hours?'  - 'Of course, Professor!'  - 'Good. Otherwise my frog won't eat it! ' "

### music

Throughout his life Hahn was a "great music lover", as he called himself, who liked to go to concerts and opera performances whenever possible. While he was still enthusiastic about Richard Wagner in his youth , his musical interests became more selective and diverse with increasing age. Later on, he mainly preferred the works of Beethoven , Brahms and Tchaikovsky and before the First World War even belonged to a Berlin choir with his tenor voice, which occasionally took part in the house music evenings of the Planck and Harnack families . Lise Meitner particularly remembered singing together in the KWI's laboratory:

Otto Hahn in June 1965 on a steamboat trip to Speyer

“When I think back to our more than 30 years of collaboration, apart from the scientific experiences, my strongest and dearest memories are of Hahn's almost indestructible cheerfulness and cheerful disposition, his constant willingness to help and his joy in music. Although he does not play an instrument, he is extremely musically gifted, with very good musical hearing and an exceptionally good musical memory. I remember that he used to sing or whistle the themes of all movements of all Beethoven symphonies and some themes of Tchaikovsky symphonies. When he was in a particularly good mood, he would whistle large parts of Beethoven's violin concerto and sometimes intentionally change the rhythm of the last movement just to be able to laugh at my protest. As long as we worked in Emil Fischer's so-called wood workshop , where we didn't have any assistants, we often sang Brahms songs in two voices, especially when the work went well. "

- Lise Meitner

### literature

Hahn, who had already developed a growing interest in literature, especially in poetry, during his student days (for example in the poems of Christian Morgenstern , many of which he could recite by heart into old age), stood with several poets and Writers in close contact, u. a. with Reinhold Schneider , Carl Zuckmayer , Alice von Herdan , Irmgard Keun , Joseph Breitbach and Eugen Roth , who once wrote him the following shaking rhyme :

Caricature by Gheorghe Manu, Romania

I proudly walk the path of life -
since I was loved by Otto Hahn.

Hahn also maintained closer contacts with some theater people, for example with the artistic director Heinz Hilpert and the actor Klaus Behrendt , especially since he never missed an opportunity to attend the performances of the Deutsches Theater in Göttingen in the 1960s . Alice von Herdan, Carl Zuckmayer's wife, wrote in her memoirs:

“On the occasion of Heinz Hilpert's 70th birthday in Göttingen, we had a delicious party with Professor Hahn, which was all the more beautiful because there was no giant table, but individual tables, where there were only four of us with Otto Hahn. I will never forget that he said goodbye to us around three o'clock after dinner with the words: 'I have to go to the store!' And that in a tone as if he were selling ties. "

Hahn had a special friendship with the banker Clemens Plassmann , who, under the anagram of his name C. Palm-Nesselmanns, was one of the most famous shake rhyme poets and dedicated some of his wonderful (Hahn) poems to Hahn, for example the collection published by the DVA Shaking rhymes:

Sometimes people jokingly call me an Otto man.
Well! So you can easily guess the dedication and motto.
I dedicate this little book to my Otto Hahn.
Always kind helps me with a motto Hahn:
I was called, who split the atom, split words.
He liked to let me play cunningly in this sport.
My splitting often - he never called it madness - amused him.
So let the collection be expanded into a little book, Hahn. -
Thanks to your heart and mind you will become a noble ancestor for posterity.

## Honors

Otto Hahn, Honorary President of the Max Planck Society since 1960, was one of the most honored and highly decorated scientists of all time. He has received many major academic, municipal, and state awards around the world.

“'Fame is a poison that humans can only tolerate in small doses,' said Honoré de Balzac . Otto Hahn is a striking exception to this rule, and that seems to me to be the most admirable thing about him. Successful student and friend of the famous Ernest Rutherford, for decades a leader in the new research field of the chemistry of radioactive substances, director of the oldest Kaiser Wilhelm Institute, finally revered as the founder of the atomic age, entrusted with high offices, showered with praise and highest honors - Hahn stayed simple, often full of self-irony, not infrequently plagued by doubts about oneself, immune to the poison Balzac spoke of. "

- Karl Erik Zimen

Hahn was an honorary doctor of numerous universities and a member or honorary member of 45 academies and scientific societies - including the University of Cambridge , the Physical Society (now the Institute of Physics ), the Royal Society and University College in London, the Romanian Physical Society in Bucharest, the Royal Spanish Society for Physics and Chemistry and the Consejo Superior de Investigaciones Científicas (CSIC) in Madrid, the Academy of Sciences in Göttingen (since 1924), the German Academy of Natural Scientists Leopoldina in Halle (1926 member, 1956 honorary member ) and the academies in Allahabad (India), Bangalore (India), Berlin, Boston (USA) , Bucharest, Göttingen, Helsinki, Copenhagen, Lisbon, Madrid, Mainz, Munich, Rome, Stockholm, Vatican and Vienna. Hahn was also an honorary member of the German Physical Society (DPG), the Society of German Chemists (GDCh), the German Bunsen Society for Physical Chemistry and the Japanese Council against Atomic and Hydrogen Bombs in Tokyo . From 1959 to 1960 he was a member of the Advisory Board of the Friedrich Naumann Foundation .

In the course of his life he received 37 highest national and international orders and medals, u. a. the Emil Fischer medal in gold, the Cannizzaro medal, the Copernicus medal, the Cothenius medal in gold from the Leopoldina, the Goethe plaque , the Paracelsus medal in gold from the Swiss Chemical Society, the Fritz Haber medal , the Max Planck Medal , the Faraday Medal of the Royal Society of Chemistry , the Wilhelm Exner Medal , the Ernst Reuter Plaque , the Theodor Goldschmidt Medal in gold, the Helmholtz Medal , the Heraeus Medal in gold, the Becquerel medal, the Harnack medal in bronze in 1954, in gold in 1959, the Marie Curie medal, the gold medal of the Massachusetts General Hospital in Boston, the medal bene merenti and the Romanian Order of Merit for Culture , the Peace class of the Order Pour le Mérite , the Greek Order of the Redeemer , the Belgian Order of the Leopold , the Order of the British Empire and the rank of Officer of the Legion of Honor from President Charles de Gaulle .

In 1954 Otto Hahn received the Great Cross of Merit with Star and Shoulder Ribbon from Federal President Theodor Heuss and in 1959 the Grand Cross of the Order of Merit of the Federal Republic of Germany . In 1961 Pope John XXIII presented him . in Rome the gold medal of the Pontifical Academy of Sciences , and in 1966 US President Lyndon B. Johnson and the United States Atomic Energy Commission in Washington, DC awarded him the Enrico Fermi Prize , together with Lise Meitner and Fritz Straßmann. They were the first foreigners to be awarded the Fermi Prize.

As early as 1957 Hahn was offered honorary citizenship of the city of Magdeburg (then GDR) and in 1958 honorary membership of the Soviet Academy of Sciences in Moscow. Hahn refused both honors.

On March 8, 1959, on the occasion of his 80th birthday, Otto Hahn was made an honorary citizen of Frankfurt am Main and his long-standing place of work in Göttingen . The first of the two documents summarizes:

“The hometown of Frankfurt is honoring a scholar of international repute who enjoys an outstanding reputation in the world for pioneering discoveries in the fields of atomic research, radioactivity and radiochemistry. At the same time, she recognizes her connection with a personality of unusual talent and creativity, whose scientific and administrative work serves the progress and the well-being of all humanity. "

Lise Meitner , who had come from Stockholm especially to congratulate her friend Otto Hahn, wrote in a public congratulatory address:

“Your 80th birthday will bring you proof from all over the world that you, as a person and scientist, have earned the love, admiration and gratitude of at least two generations of people and that you are a very hard-to-reach role model for the youngest generation. May you enjoy it in health and joy for a long time to come. - In old friendship, your Lise. "

Before Theodor Heuss had ended his ten-year term in 1959, Otto Hahn was proposed by several public figures, including the Free Democratic Party (FDP), to succeed Heuss for the office of Federal President . But he declined for reasons of age - with the famous ironic words: “That would never be an option anyway. Two eighties in Bonn? One is enough and yo ... "(Federal Chancellor Adenauer was already 83 at the time)

On June 17, 1968, the " Day of German Unity ", the Senate and House of Representatives appointed Otto Hahn an honorary citizen of the state and the city of Berlin . Senator Werner Stein explained the reason:

“His name is far too big to belong to just one city, even one nation. We knew this when, at the end of his life, we offered him a title that can only imperfectly express our respect and gratitude. It is an honor for Berlin to be able to associate its name with the history of the city in this way. Berlin bows to the life and work of Otto Hahn. This city is also deeply indebted to him. "

### Post fame

Hahn monument at the place where he was born at the Kleinmarkthalle in Frankfurt, unveiled in 1978
Bust of the
Knud Knudsen memorial

Two years after his death, American researchers suggested naming the newly synthesized element No. 105 hahnium in his honor , but in 1997 it was finally named Dubnium by the IUPAC after the Russian research center in Dubna . In 1994 the IUPAC proposed the name Hahnium for element No. 108, but the element has been called Hassium since 1997 . Furthermore, the only nuclear-powered European ship , the nuclear freighter NS Otto Hahn , was named after him in 1964 , as were two intercity trains of the Deutsche Bundesbahn in 1971 (route Hamburg-Altona - Basel SBB). The following awards were created in his honor and in his memory: Otto Hahn Prize , Otto Hahn Award , Otto Hahn Medal and Otto Hahn Peace Medal .

5 DM coin of the Federal Republic of Germany, 1979

Numerous cities and municipalities in the German-speaking area named comprehensive schools, secondary schools and high schools after him, and countless streets, squares, bridges and paths in Europe bear his name. Several countries honored Otto Hahn with editions of medals, coins and stamps (including the Federal Republic of Germany, the GDR, the USA, Portugal, Austria, Angola, Hungary, Ghana, Guinea-Bissau, Madagascar, Somalia, Romania, Moldova, the Chad, Cuba, Dominica, St. Vincent and the Grenadines).

Otto Hahn is immortalized on the Frankfurt stairs . At the site of the house where he was born, next to the western entrance to the Kleinmarkthalle Frankfurt, there is now a monument. An island in Antarctica ( Hahn Island, near Mount Discovery) was also baptized in his name, as was the Otto Hahn Library in Göttingen and the Otto Hahn Institute in Mainz . In March 1959, the Hahn-Meitner Institute for Nuclear Research (HMI) was inaugurated by the Governing Mayor of Berlin, Willy Brandt , in the presence of the namesake . In 1974 a wing of the Weizmann Institute of Science in Rehovot (Israel) was named Otto Hahn Wing in recognition of Otto Hahn's special services to German-Israeli relations . The Saint Louis University in Baguio City (Philippines) also named one of its research buildings as the Otto Hahn Building, and there are Otto Hahn lecture halls in various universities and institutes (for example in Berlin, Heidelberg and Kiel ).

In several cities and communities, busts, monuments and memorial plaques were unveiled in his honor, including in Albstadt- Tailfingen, Ankara , Berlin (East and West), Boston (USA), Frankfurt am Main, Göttingen, Gundersheim (Rheinhessen), Mainz, Marburg, Munich (in the hall of honor of the Deutsches Museum), Punta San Vigilio (Lake Garda), Rehovot ( Israel ) and Vienna (in the foyer of the IAEA ). Public Otto Hahn Centers were created in the city of Göttingen and the municipality of Ottobrunn (near Munich) . An Otto Hahn Center is also planned in Frankfurt am Main , which will, among other things, house a permanent exhibition on Hahn's life and work. Since 2011 there has also been an Otto Hahn memorial in Albstadt-Tailfingen in the academy of the Reutlingen Chamber of Industry and Commerce located there, which commemorates Hahn's work in Tailfingen from 1944 to 1945. At the beginning of 2014, two new Otto Hahn libraries were opened in the Dortmund University Library as departmental libraries for natural sciences.

The International Astronomical Union (IAU) honored Hahn by naming a moon crater (together with Count Friedrich II. Von Hahn ) and - at the suggestion of the astronomer Freimut Börngen  - the minor planet (19126) Ottohahn . Otto Hahn received a special honor in the Netherlands: after an azalea ( Rhododendron luteum Otto Hahn ) and a cactus ( Trichocereus echinopsis hybrid Otto Hahn ) had already borne his name, a new rose was christened by Dutch rose breeders, the Rosa ottohahniana . Even a cocktail that was particularly popular in the 1950s and 1960s was named after him: The "Otto Hahn" consists of two equal parts whiskey (e.g. Balvenie or Macallan ) and rich golden sherry (e.g. Osborne or Sandeman ) and is served in previously warmed cognac glasses. In the city center of Rotterdam (Ommoord) there has also been a well-frequented restaurant and music venue that bears his name for years: Café Otto Hahn.

## Fonts

Publications (selection)
• The parent substance of actinium, a new radioactive element with a long lifespan. (together with Lise Meitner). In: Physikalische Zeitschrift, No. 19, 1918.
• What does radioactivity teach us about the history of the earth? Springer Verlag, Berlin 1926.
• Applied Radiochemistry. Cornell University Press, Ithaca, New York. Humphrey Milford, London. Oxford University Press 1936. (Also Russian edition).
• The chemical elements and natural types of atoms. Springer Verlag, Berlin 1938.
• Natural and artificial transformations of the atomic nuclei. Schroll publishing house, Vienna 1941.
• Artificial atomic transformations and the fission of heavy nuclei. (Publications of the German Scientific Institute , Stockholm, Series 3: Natural Sciences, No. 1), Almquist & Wiksells, Stockholm 1944.
• From the natural transformation of uranium to its artificial splitting. 1948.
• The uranium chain reaction and its meaning. 1948 (also Spanish edition).
• Artificial new elements. Verlag Chemie, Weinheim 1948.
• New Atoms. (Edited by W. Gaade), Elsevier, Amsterdam – London – New York – Bruxelles 1950. (English and Dutch editions).
• Harnessing the energy of the atomic nucleus. Oldenbourg Verlag, Munich 1950.
• Cobalt 60 - danger or blessing for humanity? Musterschmidt Verlag, Göttingen 1955.
• Modern alchemy. Wuppertal 1960 (publications of the United Glanzstoff Fabriken AG).
• From radiothor to uranium fission. A scientific autobiography. Friedr. Vieweg Verlag, Braunschweig 1962 (also American, English and Italian editions).
• My life. Bruckmann Verlag, Munich 1968 (5th edition 1969, also English, American and Japanese editions).
estate

Otto Hahn's official estate can be found in the archive on the history of the Max Planck Society .

## Secondary literature

• Hans Hartmann: Otto Hahn. The discoverer of atomic fission. Lux, Murnau – Munich – Innsbruck – Basel 1961.
• Laura Fermi : The Story of Atomic Energy. Random House, New York 1962.
• Eckart Heimendahl: pioneer of our future. Wunderlich, Tübingen 1968.
• Ernst H. Berninger: Otto Hahn - A picture documentation. Moos, Munich 1969.
• Friedrich Herneck : pioneer of the atomic age. Verlag der Morgen, Berlin 1970.
• Robert Spence : Otto Hahn. (= Biographical Memoirs of Fellows of the Royal Society. Volume 16). London 1970.
• Ernst H. Berninger: Otto Hahn 1879–1968. (English and Spanish editions). Inter Nationes, Bonn – Bad Godesberg 1970.
• Hans D. Graetzer, David L. Anderson : The Discovery of Nuclear Fission. Nostrand – Reinhold, New York 1971.
• Ernst H. Berninger: Otto Hahn in self-testimonies and photo documents. Rowohlt, Reinbek near Hamburg 1974.
• Franz Baumer: Otto Hahn. (= Heads of the 20th century). Colloquium, Berlin 1974.
• Dietrich Hahn (ed.): Otto Hahn - experiences and knowledge. With an introduction by Karl-Erik Zimen . Econ, Düsseldorf / Vienna 1975, ISBN 3-430-13732-2 .
• Klaus Hoffmann: Otto Hahn - Stations from the Life of a Nuclear Researcher. Foreword by Manfred von Ardenne . New life, Berlin 1978.
• Anthony Feldman, Peter Ford: Otto Hahn. In: Scientists and Inventors. Aldus Books, London 1979.
• Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. A biography in pictures and documents. With a foreword by Reimar Lüst , a foreword by Paul Matussek and an introduction by Walther Gerlach . List, Munich 1979, ISBN 3-471-77841-1 .
• Horst Wohlfahrt (ed.): 40 years of nuclear fission. An introduction to the original literature. Scientific Book Society, Darmstadt 1979.
• Ronald W. Clark : The Greatest Power on Earth: The Story of Nuclear Fission. Sidgwick & Jackson, London 1980, ISBN 0-283-98715-4 .
• Dietrich Hahn (Ed.): Otto Hahn in the criticism. Moos, Munich 1981.
• Cornelius Keller: The History of Radioactivity. Scientific publishing company, Stuttgart 1982.
• William R. Shea (Ed.): Otto Hahn and the Rise of Nuclear Physics. Reidel, Dordrecht / Boston / Lancaster 1983.
• Pierre Radványi , Monique Bordry: La Radioactivité artificielle et son histoire. Seuil CNRS, Paris 1984.
• Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. (= Great Natural Scientists. Volume 45). Wissenschaftliche Verlagsgesellschaft, Stuttgart 1984, ISBN 3-8047-0757-2 .
• Alwyn McKay : The Making of The Atomic Age. Oxford University Press, Oxford / New York 1984.
• Dietrich Hahn (Ed.): Otto Hahn - My life. The memories of the great atomic researcher and humanist. Extended new edition. Piper, Munich 1986, ISBN 3-492-00838-0 .
• Karl-Erik Zimen : Radiant Matter. Radioactivity - a piece of contemporary history. Bechtle, Esslingen / Munich 1987.
• Dietrich Hahn (Ed.): Otto Hahn. Life and work in texts and pictures. Foreword by Carl Friedrich von Weizsäcker . Insel, Frankfurt am Main 1988, ISBN 3-458-32789-4 .
• Richard Rhodes : The Making of the Atomic Bomb. Simon and Schuster, New York 1988.
• Dietrich Hahn (Ed.): Otto Hahn - From Radiothor to Uranium Fission. Extended new edition. With a foreword by Kurt Starke . Vieweg, Braunschweig / Wiesbaden 1989, ISBN 3-528-08413-8 .
• Jost Lemmerich : The story of the discovery of nuclear fission. Exhibition catalog. Technical University of Berlin 1989.
• Klaus Hoffmann: Otto Hahn. Guilt and responsibility. Springer, Heidelberg 1993.
• JA Revill, Sir Charles Frank (Ed.): Operation Epsilon. The Farm Hall Transcripts. IOP Publishing, Bristol / Philadelphia 1993.
• Michael Salewski (ed.): The age of the bomb. The story of the atomic threat from Hiroshima to the present day. Beck, Munich 1995.
• Elisabeth Kraus: From the fission of uranium to the Göttingen Declaration. Otto Hahn, Werner Heisenberg, Carl Friedrich von Weizsäcker and the responsibility of the scientist. Königshausen & Neumann , Würzburg 2001.
• Klaus Hoffmann: Otto Hahn. Achievement and Responsibility. Springer, New York 2001.
• Horst Kant : Otto Hahn and the Declarations of Mainau and Göttingen. Berlin 2002.
• Jim Whiting: Otto Hahn and the Discovery of Nuclear Fission. Mitchell Lane, Hockessin 2004.
• Klaus Hoffmann: Otto Hahn - Research and Responsibility. Kramer, Frankfurt am Main 2005.
• Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. Hirzel, Stuttgart 2005, ISBN 3-7776-1380-0 .
• Angelika Sauer: The Diasporic Moment: Elise von Koerber, Dr. Otto Hahn, and the attempt to create a German diaspora in Canada. In: German Diasporic Experiences: Identity, Migration, and Loss. Ed. Mathias Schulze et al., Wilfrid Laurier University Press, Waterloo 2008, pp. 205-216.
• Volker Lässing: “Nobody gets the devil!” - Otto Hahn and the Kaiser Wilhelm Institute for Chemistry in Tailfingen. Preface by Dietrich Hahn. CM-Verlag, Albstadt 2010, ISBN 978-3-939219-00-2 .
• Hubert Mania: Chain Reaction - The History of the Atomic Bomb. Rowohlt, Reinbek 2010, ISBN 978-3-498-00664-8 .
• Robert Lorenz: Otto Hahn. The atomic curse and blessing. In: Stine Marg, Franz Walter (Hrsg.): Göttingen heads and their work in the world. Göttingen 2012, ISBN 978-3-525-30036-7 , pp. 89-93.
• Uli Suckert: Anno 1938 - When the world changed - Otto Hahn and Manfred von Ardenne on the wheel of history. Weltbuch Verlag, Dresden 2012, ISBN 978-3-938706-32-9 .
• Richard von Schirach : The night of the physicists. Heisenberg, Hahn, Weizsäcker and the German bomb. Berenberg, Berlin 2012, ISBN 978-3-937834-54-2 .
• Horst Kant , Carsten Reinhardt: 100 years of the Kaiser Wilhelm / Max Planck Institute for Chemistry (Otto Hahn Institute). MPG, Berlin 2012, ISBN 978-3-927579-26-2 .
• Volker Lässing: Research in the shadow of the Zollernburg. The Kaiser Wilhelm Institutes and their Nobel Prize winners in Hechingen, Haigerloch and Tailfingen. CM-Verlag, Albstadt 2013. ISBN 978-3-939219-02-6 .
• Vera Keizer (Ed.): Radiochemistry, Diligence and Intuition. New research on Otto Hahn. GNT-Verlag, Diepholz and Berlin 2018, ISBN 978-3-86225-113-1 .

## Movies

Documentaries

• Otto Hahn. (Series: Dreams That Did n't Stay ) Director: Ernst von Khuon . SDR / ARD 1983 (30 min.).
• Lise Meitner. (Series: Dreams That Did n't Stay ) Director: Ernst von Khuon. SDR / ARD 1984 (30 min.).
• Otto Hahn. Director: Wilfried Viebahn. WDR / ARD 1988 (45 min.).
• Otto Hahn. Director: Wilfried Viebahn. WDR 1988 (15 min.).
• Otto Hahn. Director: Klaus Dexel. SDR 1988 (45 min.).
• Otto Hahn 1879–1968. Director: Peter Regenyi. Transtel / Deutsche Welle 1989 (30 min.). Broadcast worldwide in five dubbed versions - English, Spanish, French, Portuguese and Arabic.
• Otto Hahn and nuclear fission. (Series: Milestones in Science and Technology. ) Director: Werner Kiefer. Target / ARD 1992 (15 min.).
• Otto Hahn - 25th anniversary of death. (Series: The historical keyword. ) Director: Joachim G. Schmidt. BR 1993 (5 min.).
• Otto Hahn and Lise Meitner - From Nuclear Fission to the Atomic Bomb. Director: Rhan Gunderlach. Zebra / Deutsche Welle 1995 (30 min.).
• Lise Meitner and Otto Hahn. Director: Rosemary Reed. BBC 2005. German version: ZDF 2006 (45 min.).
• Otto Hahn - From the life of a Nobel Prize winner in Göttingen 1946–1968. Director: Matthias Heinzel. Göttinger Tageblatt 2007 (45 min.).

motion pictures

All of the following quotations are taken from Dietrich Hahn (ed.): Lise Meitner: Memories of Otto Hahn.

Albert Einstein , Princeton (USA), 1949, on Hahn's work from 1933 to 1945:
"One of the few who stayed upright and did their best during these evil years."

Lise Meitner , Stockholm, 1949:
“Otto Hahn knew how to approach the most difficult problems with the simplest tools, guided by his unusual intuitive talent and his equally unusual, versatile knowledge of chemistry. How often have I not seen in the long years of our collaboration that he has grasped problems that the physicist makes clear with mathematical formulas purely intuitively and clearly. "

Lise Meitner in a personal conversation with Otto Hahn:
"Chicken, you don't understand anything about physics, go upstairs!"

Max Born , Bad Pyrmont, 1955:
"One of the noblest and finest people I have ever met."

Lise Meitner, Stockholm, 1959:
"The great reliability of his character, his natural amiability and joy in joking have never left him, even in difficult discussions, scientific or human."

Manfred Eigen , Göttingen, 1968:
"Although Otto Hahn was one of the few scientists who made history and determined an entire era of world politics, he never felt himself to be a figure in world politics."

Fritz Straßmann , Mainz, 1968:
“The number of those who could stand next to Otto Hahn is small. For him, his own way of acting was a matter of course, but it can be a role model for future generations, regardless of whether one admires his human and scientific sense of responsibility or his personal courage in Otto Hahn's attitude. Both together could rarely be found in one person, and so this rare gift Otto Hahn acquired and secured the love and admiration of his friends and students, and it will hopefully become the aspired goal of many young people after his death. "

Berta Karlik , Vienna, 1969:
“Otto Hahn faced such a difficult human fate with an incomparable attitude. Outwardly he always remained cheerful, turned towards his fellow men with never-ending kindness of heart, a wonderful example of moral strength. Everyone who was allowed to meet him will perceive the memory of his unique personality as an inalienable inner possession. "

Manfred von Ardenne , Dresden, 1978:
“Everyone who knew Otto Hahn had to adore him as a researcher in his work and as a person in his actions and thoughts. He was a role model in his conscientiousness, at the same time winning hearts in his kindness and humility. "

Elizabeth Rona , Miami (USA), 1978:
"I have often thought that he deserved a second Nobel Prize - the Nobel Peace Prize."

Wolfgang Gentner , Heidelberg, 1979:
“Just as he could never forget the persecution of the Jews in the Third Reich, he also used the first opportunity to establish relations with the new state of Israel. It was his last big trip that made an unforgettable impression on him. "

Otto Haxel , Heidelberg, 1987:
“I just have to say that he is the most admirable person I know among scientists. His great character, his sharpness of mind and this absolute honesty and neglect of his person will not be found again so quickly. "

Carl Friedrich von Weizsäcker , Starnberg, 1988:
“Humanity cannot live in the long run with knowledge of nuclear fission and the institution of war. This knowledge shadowed the last decades of Otto Hahn's life. To have worn it consciously was his contribution to the indispensable change in consciousness of our time. It was his gift to humanity. "

Commons : Otto Hahn  - Collection of images, videos and audio files

## Individual evidence

1. ^ Glenn T. Seaborg: Introduction to: Otto Hahn: A Scientific Autobiography. Charles Scribner's Sons, New York 1966, p. IX.
2. At the end of 1999 the news magazine Focus published the result of a survey among 500 leading German scientists, engineers and medical professionals about the most important researchers of the 20th century (issue 52/1999, pp. 103-108, online ). The experimental chemist Otto Hahn was chosen - after the theoretical physicists Albert Einstein and Max Planck  - in third place and thus the most important empirical natural scientist of the century.
3. Jan Philipp Bornebusch: Grandfather of the atomic bomb. On: Spektrum.de. Retrieved April 10, 2013.
4. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher life of our time. Große Naturforscher, Volume 45. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, ISBN 3-8047-0757-2 .
5. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, p. 14 f.
6. Otto Hahn: My life. Verlag F. Bruckmann, Munich 1968, p. 32.
7. Otto Hahn: My life. Extended new edition. Piper Verlag, Munich / Zurich 1986, ISBN 3-492-00838-0 , p. 46.
8. Life data, publications and academic family tree of Otto Hahn at academictree.org, accessed on February 8, 2018.
9. ^ In: Lecture at the 2nd meeting of Nobel Prize winners. Lindau, June 23, 1952.
10. Otto Hahn: My life. Verlag Bruckmann, Munich 1968, p. 75.
11. Otto Hahn: On some properties of the alpha-rays from Radiothorium. (Comm. By Prof. E. Rutherford). In: Phil. Mag. (6), 11, 1906, pp. 793-805.
12. Ernest Rutherford, Otto Hahn: Mass of the alpha particles from Thorium. In: Phil. Mag. (6), 12, 1906, pp. 371-378.
13. ^ "Wood workshop" as the first laboratory under Emil Fischer. ( Memento from December 11, 2013 in the Internet Archive ).
14. Otto Hahn: About a new phenomenon in activation with actinium. In: Physikalische Zeitschrift. 10, 1909, p. 81.
15. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Große Naturforscher, Volume 45. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, pp. 40–41.
16. ^ O. Hahn, St. Meyer, E. v. Schweidler: Report on the meeting of the international radium standards commission in Paris from March 25 to 28, 1912. Physikalische Zeitschrift, 13th vol., No. 11, 1912.
17. ^ Lise Meitner to Otto Hahn, April 9, 1912. In: Dietrich Hahn (Hrsg.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, ISBN 3-458-32789-4 , p. 83.
18. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Große Naturforscher, Volume 45. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, pp. 140 f.
19. Otto Hahn: My life. Verlag F. Bruckmann, Munich 1968, p. 103.
20. Otto Hahn: My life. Bruckmann, Munich 1968, pp. 111-117.
21. a b Otto Hahn: My life. Bruckmann, Munich 1968, pp. 117-132.
22. ^ Dietrich Stoltzenberg: Fritz Haber. Wiley-VCH, Weinheim 1994, ISBN 3-527-29206-3 , pp. 223-350.
23. ^ Dietrich Stoltzenberg: Fritz Haber: Chemist, Nobel Prize Winner, German, Jew. Wiley-VCH, Weinheim 1994, ISBN 3-527-29206-3 , pp. 286 f.
24. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, p. 55 f.
25. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Große Naturforscher, Volume 45, Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, ISBN 3-8047-0757-2 , p. 142.
26. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, p. 48 f.
27. ^ A. Born: Review in: The natural sciences. 15th year, 1927, 13.
28. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, ISBN 3-458-32789-4 , p. 130.
29. ^ Glenn T. Seaborg: Introduction to Otto Hahn. A Scientific Autobiography. Scribner's, New York 1966.
30. Ernest Rutherford to Otto Hahn, April 25, 1935. In: Dietrich Hahn (Hrsg.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, ISBN 3-458-32789-4 , p. 159.
31. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, p. 167.
32. ^ I. Curie, P. Savitch: Sur les radioéléments formés dans l'uranium irradié par les neutrons II. In: Le Journal de Physique et le Radium. 9 (1938), pp. 355-359.
33. ^ Karl Erik Zimen: Radiant matter: radioactivity - a piece of contemporary history. Bechtle Verlag, Esslingen and Munich, 1987. P. 57. ISBN 3-7628-0464-8 .
34. Otto Hahn, Fritz Strassmann: Evidence of the formation of active barium isotopes from uranium and thorium by neutron irradiation; Evidence of further active fragments in the uranium fission. In: The natural sciences. 27, 1939, pp. 89-95, doi: 10.1007 / BF01488988 .
35. ^ Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. S. Hirzel Verlag, Stuttgart 2005, p. 74.
36. a b c d Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. S. Hirzel Verlag, Stuttgart 2005, p. 50.
37. Lise Meitner: Otto Hahn - the discoverer of uranium fission. In: H. Schwerte and W. Spengler (eds.): Researchers and scientists in today's Europe. Verlag Stalling, Oldenburg and Hamburg 1955, pp. 149–157.
38. ^ Hans Joachim Born, Fritz Straßmann: Otto Hahn. In: Radiochimica Acta 9/2, 1968. p. 3.
39. Aliki Nassoufis: Declaration from the Swedish exile. In: Märkische Oderzeitung. December 19, 2008, Blickpunkt p. 3.
40. Martin Trömel: Friends until death - Otto Hahn and Lise Meitner. In: Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 2005. p. 151.
41. ^ Berta Karlik to Erika Cremer, April 2, 1979. In: Anne Hardy / Lore Sexl: Lise Meitner. Rowohlt Verlag, Reinbek, 2002, ISBN 3-499-50439-1 , p. 122.
42. Otto Robert Frisch: Atomic energy - how it all began. In: Carl Seelig (ed.): Helle Zeit - Dark Zeit. In Memoriam Albert Einstein. Vieweg Verlag, Braunschweig / Wiesbaden 1986. p. 124. ISBN 3-528-08934-2 .
43. Otto Hahn to his brother Heiner, February 17, 1944. In: Dietrich Hahn (Ed.): Otto Hahn. Suhrkamp-Insel, Frankfurt am Main 1988, p. 198.
44. ^ Hans Joachim Born, Fritz Strassmann: Otto Hahn. In: Radiochimica Acta. 9/2, 3, 1968.
45. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 2005, p. 108.
46. Wolf Jobst Siedler: Oral statement. In: Reich capital private - A mirror of customs. Episode 4: The big city as a burrow. Contemporary witnesses describe the years 1941 to 1945. A film by Horst Königstein . Broadcast on October 25, 1987 on Bavarian television.
47. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Verlag Insel-Suhrkamp, ​​Frankfurt am Main 1988.
48. ^ Edith Hahn to James and Ingrid Franck, April 22, 1933. (The Joseph Regenstein Library, University of Chicago). See also: Jost Lemmerich (Ed.): Max Born - James Franck. The luxury of conscience. Physicists in their day. Exhibition catalog, Wiesbaden 1982.
49. ^ Max von Laue: Otto Hahn on March 8, 1959. In: Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. S. Hirzel Verlag, Stuttgart 2005, ISBN 3-7776-1380-0 , p. 57.
50. Hans Götte: Otto Hahn - The researcher and man. In: Frankfurter Neue Presse. July 30, 1968.
51. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, pp. 204-205.
52. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft, Stuttgart 1984, ISBN 3-8047-0757-2 , p. 116.
53. Dieter Hoffmann (Ed.): Operation Epsilon - The Farmhall Protocols. Rowohlt Verlag, Berlin 1993, ISBN 3-87134-082-0 , p. 66.
54. German Society for the United Nations (DGVN), LV Berlin-Brandenburg (ed.): Documentation on the award of the Otto Hahn Peace Medal 2012 to Prof. Dr. Tadatoshi Akiba. Berlin 2013, pp. 27–28.
55. Werner Heisenberg: The part and the whole. Conversations in the area of ​​atomic physics. Piper Verlag, Munich 1969.
56. Friedrich Herneck: Pioneers of the atomic age. 8th edition. Der Morgen publishing house, Berlin (GDR) 1979.
57. Newsletter of the German Science and Technology, organ of the Reich Research Council (Hrsg.): Research and progress . Staff news. German science and abroad. tape 19, 23/24 , 1943, pp. 252 .
58. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main, 1988, ISBN 3-458-32789-4 , p. 216.
59. Lise Meitner Birgit Broomé-Aminoff, November 20, 1945. In: Anne Hardy, Lore Sexl: Lise Meitner. Rowohlt Verlag, Reinbek, 2002, ISBN 3-499-50439-1 , p. 119.
60. Carl Seelig (ed.): Helle Zeit - Dark Zeit. In memoriam Albert Einstein. Europa Verlag, Zurich 1956 (Vieweg, Braunschweig 1986, ISBN 3-528-08934-2 ).
61. Walther Gerlach: Development and importance of radioactivity. Speech. In: State Otto Hahn Gymnasium, Landau i. d. Palatinate. Naming ceremony, September 23, 1967. Reprint 1967. p. 42.
62. Elizabeth Rona: How it came about: Radioactivity, Nuclear Physics, Atomic Energy. Oak Ridge Associated Universities (ORAU), Oak Ridge, Tennessee, USA 1978.
63. Nomination Database - Otto Hahn
64. ^ Nobelprize.org.
65. ^ Rudolf Augstein: Many letters for Professor Hahn. In: Der Spiegel . Volume 1, No. 2, pp. 19-20, January 11, 1947.
66. Erika Weisenborn: An encouraging act. Letter to the editor. In: Der Spiegel. Volume 1, No. 3, p. 22, January 18, 1947.
67. ^ Adolf Butenandt: memorial words. In: Special issue of the messages from the Max Planck Society. October 1968, p. 12 f.
68. Werner Heisenberg: Memorial words for Otto Hahn. Order of Pour le Mérite. Speeches and memorial speeches. Bonn 1969. In: Dietrich Hahn (Ed.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf / Vienna 1975, ISBN 3-430-13732-2 , p. 261 f.
69. Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, ISBN 3-8047-0757-2 , p. 124 f.
70. ^ Otto Hahn: Research and Technology - Freedom and Responsibility. Speech given on the occasion of the opening of ACHEMA IX in July 1950. In: Dietrich Hahn (Hrsg.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf / Vienna 1975, ISBN 3-430-13732-2 , pp. 189-198.
71. ^ Otto Hahn to Frédéric Joliot-Curie, February 2, 1951. In: Dietrich Hahn (Hrsg.): Otto Hahn - life and work in texts and pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 243. ISBN 3-458-32789-4 .
72. Otto Hahn: Cobalt 60 - Danger or Blessing for Humanity? Musterschmidt Verlag, Göttingen 1955.
73. Otto Hahn: My life. Piper Verlag, Munich / Zurich 1986.
74. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. List Verlag, Munich 1979, p. 249.
75. ^ Lise Meitner: Otto Hahn - The discoverer of the fission of uranium. In: H. Schwerte and W. Spengler (eds.): Researchers and scientists in today's Europe. Stalling Verlag, Oldenburg-Hamburg 1955, p. 157.
76. Calendar sheet December 22nd. Deutsche Welle, accessed on September 1, 2012 .
77. ^ The Observer, London, June 9, 1957. In: Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984, ISBN 3-8047-0757-2 , p. 184.
78. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. A biography in pictures and documents. List Verlag, Munich 1979, ISBN 3-471-77841-1 , p. 284.
79. Reinhold Schneider: Winter in Vienna - From my notebooks 1957/1958. Herder, Freiburg-Basel-Wien 1958 (current: Herder, Freiburg i. Br. 2003, ISBN 3-451-28113-9 ).
80. ^ New Germany, December 6, 1957. In: Dietrich Hahn (Hrsg.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp- Insel Verlag , Frankfurt am Main 1988, ISBN 3-458-32789-4 , p. 289.
81. Dietrich Hahn (Ed.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf – Vienna 1975. pp. 223–225. ISBN 3-430-13732-2 .
82. Dietrich Hahn (Ed.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf – Vienna 1975. p. 223. ISBN 3-430-13732-2 .
83. ^ Harry Gilroy: Hahn sees atomic shorn of terror etc. In: New York Times. May 31, 1958.
84. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 345. ISBN 3-458-32789-4 .
85. Otto Hahn to Koshiro Okakura, January 29, 1958. In: Dietrich Hahn (Hrsg.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 311. ISBN 3-458-32789-4 .
86. ^ Message from Prof. Otto Hahn, September 1960. In: Dietrich Hahn (Hrsg.): Otto Hahn - life and work in texts and pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 311. ISBN 3-458-32789-4 .
87. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. A biography in pictures and documents. List Verlag, Munich 1979, p. 321.
88. Sir Karl Popper: Address. In: UN-Forum, special edition of the announcements of the Landesverband Berlin eV of the German Society for the United Nations (DGVN). Berlin 1994. p. 36 f.
89. ^ Otto Hahn: Letter to Eelco van Kleffens. December 17, 1954. In: Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, p. 256.
90. Karl Winnacker: Never lose heart - memories of fateful years in German chemistry. Econ Verlag, Düsseldorf / Vienna 1971.
91. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. P. 270. ISBN 3-458-32789-4 .
92. ^ Theodor Heuss: Speech at the general meeting of the Max Planck Society in Stuttgart, June 13, 1956.
93. Notebook Otto Hahn, 13./14. July 1956. In: Dietrich Hahn (Hrsg.): Otto Hahn - life and work in texts and pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 272.
94. Otto Hahn's notebook, March 21, 1958.
95. Otto Hahn: Atomium - symbol of international cooperation in science. Speech given on June 18, 1958 at the World's Fair in Brussels. In: Dietrich Hahn (Ed.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf / Vienna 1975, ISBN 3-430-13732-2 , pp. 227-239.
96. Dietrich Hahn (ed.): Otto Hahn. List Verlag, Munich 1979, p. 294.
97. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. (Foreword: Carl Friedrich von Weizsäcker ). Verlag Insel-Suhrkamp, ​​Frankfurt am Main 1988, ISBN 3-458-32789-4 .
98. ^ Klaus Hoffmann: Otto Hahn - Guilt and Responsibility - Conflicts of a Scientist. Springer Verlag, Heidelberg-Berlin-New York a. a. 1996.
99. ^ German Society for the United Nations (DGVN), LV Berlin. UN Forum No. 1, 2002.
100. ^ Klaus Hoffmann: Otto Hahn - Stations from the life of a nuclear researcher. New Life Publishing House, Berlin (GDR) 1978. 345.
101. Walther Ottendorff-Simrock: From Otto Hahn to Max Liebermann - Encounters. A. Henn Verlag, Wuppertal 1970, p. 104 f.
102. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Verlag Suhrkamp-Insel, Frankfurt am Main 1988, ISBN 3-458-32789-4 , p. 339.
103. ^ Federal President Heinrich Lübke to Edith Hahn, July 28, 1968. In: Dietrich Hahn (Hrsg.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf / Vienna 1975, ISBN 3-430-13732-2 , p. 257.
104. ^ Klaus Hoffmann: Otto Hahn - Stations from the life of a nuclear researcher. New Life Publishing House, Berlin (GDR) 1978, p. 347 f.
105. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. List Verlag, Munich 1979, p. 349.
106. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. List Verlag, Munich 1979, p. 348.
107. Werner Heisenberg: On the death of Otto Hahn. Süddeutsche Zeitung, August 3, 1968.
108. Arndt Rühle: Review of: Otto Hahn: Mein Leben. Bruckmann, Munich 1968. In: Münchner Merkur, August 17, 1968.
109. Ernst H. Haux: Review of: Otto Hahn: Mein Leben. Bruckmann, Munich 1968. In: Der Tagesspiegel, November 16, 1968.
110. Christine Schemmann: The second life of Otto Hahn. The Nobel Prize winner was an excellent mountaineer. In: The mountaineer . 46th vol., No. 8, 1979, pp. 472-473.
111. ^ Carl Zuckmayer to Otto Hahn, April 4, 1966. In: Alpenvereins-Jahrbuch 1980. Innsbruck 1980, p. 91.
112. Alpenverein yearbook 1980. Innsbruck 1980, p. 95.
113. Hanno Hahn: Strange nursery for our Muzie. In: Our cat - Germany's first cat magazine. Volume 13, No. 3, March 1939. pp. 42-43.
114. Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988. p. 137. ISBN 3-458-32789-4 .
115. Otto Hahn: Experiences and Insights. (Ed. Dietrich Hahn). Econ Verlag, Düsseldorf – Vienna 1975. p. 241. ISBN 3-430-13732-2 .
116. Otto Hahn: My life. 6th edition. Piper Verlag, Munich / Zurich 1986, ISBN 3-492-00838-0 , pp. 89-90.
117. ^ Lise Meitner: Otto Hahn on his 80th birthday. In: The natural sciences. Vol. 46, No. 5, 1959, p. 43.
118. Eugen Roth: Dedication to man and inhuman. Munich 1961. See: Dietrich Hahn (Ed.): Otto Hahn - Life and Work in Texts and Pictures. Suhrkamp-Insel Verlag, Frankfurt am Main 1988, p. 328.
119. Quoted from: Walther Gerlach, Dietrich Hahn: Otto Hahn - A researcher's life of our time. Wissenschaftliche Verlagsgesellschaft (WVG), Stuttgart 1984. P. 200. ISBN 3-8047-0757-2 .
120. C. Palm-Nesselmanns: Schüttelreime. Deutsche Verlags-Anstalt, Stuttgart 1967, p. 5.
121. Karl Erik Zimen: Introduction to: Otto Hahn: Experiences and knowledge. (Ed. Dietrich Hahn). Econ Verlag, Düsseldorf – Vienna 1975. p. 9. ISBN 3-430-13732-2 .
122. Member entry of Otto Hahn (with picture and CV) at the German Academy of Natural Scientists Leopoldina , accessed on September 22, 2016.
123. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. A biography in pictures and documents. List Verlag, Munich 1979, ISBN 3-471-77841-1 , p. 299.
124. ^ Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. S. Hirzel Verlag, Stuttgart 2005, ISBN 3-7776-1380-0 , p. 64.
125. Dietrich Hahn (Ed.): Otto Hahn - experiences and knowledge. Econ Verlag, Düsseldorf / Vienna 1975.
126. Dietrich Hahn (Ed.): Otto Hahn - founder of the atomic age. A biography in pictures and documents. List Verlag, Munich 1979, ISBN 3-471-77841-1 , p. 345.
127. ^
128. Printer's note: Provided by the author to the German Scientific Institute in Stockholm in the context of its lectures held in Sweden in October 1943 on "Geological Age Determination and Atomic Blasting".
129. ^ Dietrich Hahn (Ed.): Lise Meitner: Memories of Otto Hahn. S. Hirzel Verlag, Stuttgart 2005, ISBN 3-7776-1380-0 , pp. 1-4.
130. Ernst Brüche (Ed.): Physicist Anecdotes: Collected and communicated by colleagues. Physik-Verlag, Mosbach / Baden 1952, p. 33.