Comment
Otto Hahn uses his 1964 Lindau lecture to give a review of his own scientific history under the theme “intricate roads to success”. He tells several anecdotes on some of his own experiments which led to insights totally different to those expected. In doing so, he also gives a review of the early development of radiophysics and -chemistry in the first half of the 20th century, fields, which he pioneered together with other great names such as Marie Curie, Ernest Rutherford and Sir William Ramsay.The style of the lecture is very similar to another excellent one given by 1963 Chemistry Laureate Karl Ziegler at the same meeting (a fact which is also acknowledged by Hahn himself). Like Ziegler, looking at his scientific life, Hahn arrives at the conclusion that following up on unexpected results can be highly rewarding - if paired with patience and self-criticism. Hahn’s first anecdote concerns the discovery of radiothorium, which he made in the laboratory of 1904 Chemistry Laureate William Ramsay in 1905. While his visit was merely intended to provide him with sufficient English language skills to start a career in a chemical plant, the result was the discovery of what was believed to be a new element at the time. Later it was shown that radiothorium is in fact not a new element but an isotope of the previously known element thorium. Nonetheless, Ramsay naturally recognized that Hahn’s unexpected result was quite outstanding and tried to convince him to work towards a professorship in the laboratory of his friend and 1902 Chemistry Laureate Emil Fischer. Hahn declined, not feeling up for the task at the time. Instead he went to the laboratory of 1908 Nobel Laureate Ernest Rutherford in Canada. There, he discovered radioactinium, another thorium isotope. In 1906, Hahn returned to Germany and continued his work in Berlin. It was also in Berlin where he eventually showed the nuclear fission of uranium, which entailed the 1944 Nobel Prize in Chemistry. Hahn recounts that, when he shared news of this discovery with 1922 Physics Laureate Niels Bohr in Copenhagen, Bohr almost missed the train taking him towards his ship to the US. However, Hahn also does not abstain from acknowledging, that his discovery paved the way for the nuclear bombs dropped on Hiroshima and Nagasaki. The attentive listener might notice that the otherwise eloquent Hahn is groping for words in this part of his talk. On other occasions, Hahn had made no secret of his rejection of nuclear warfare. In a further anecdote from his time in Berlin, Hahn narrates how he (almost) radioactively contaminated the German emperor Wilhelm II. In fact, Wilhelm II appeared to be very interested in radioactivity phenomena and upon the opening of the first “Kaiser Wilhelm Institute” (a national research centre) in Berlin, Hahn demonstrated the effect of radiothorium (i.e. the nuclide 228thorium) radiation on a fluorescent screen. An experiment, which was later forbidden due to detrimental effects of the emitted radiation. However, as Hahn recalls, the emperor liked the experiment and witnessing it did not keep him from living a long life. David Siegel