Georg Placzek – a critical link in the making of the atom bomb

To his many Nobel Prize-winning colleagues, Georg Placzek was a physicist of boundless importance. It was not because of a breakthrough discovery on his part, or because he published widely, but because he tended to be the man with the right wits at the right time. At Los Alamos, New Mexico, on July 16th, 1945, he was the only Czech present for the detonation of the first nuclear explosion – an event he had helped to create.

He died young, at the age of 50, and for a long time hardly anyone in Czechoslovakia knew of his importance. Some 60 years after he left his homeland forever, he was brought to public attention by Czech physicist Jan Fischer, who among other things was impressed to learn there had been much grief among the world’s great physicists when Placzek died in 1955.

“He was appreciated much more abroad than in his home country – in his home country he was completely unknown. So I became proud of my countryman and I thought this was very nice that people abroad appreciated him and this made me interested in him.”

It’s a strong testament to half a century’s seclusion that the Placzeks’ name had been forgotten in their hometown of Brno. Georg’s great-grandfather and grandfather had been important Moravian rabbis, the latter being of a scientific bent, a close friend of Gregor Mendel’s and a pen-pal of Charles Darwin’s. His father ran a large textile mill, and was honoured for the humanity he had shown the community in the First War though the care and opportunities he afforded the poor. It was a popular family that was well-knit into its multinational society.

“Placzek grew up in a milieu of mixed nations: Czechs, Moravians, Jews and Germans. And I think it is a unique milieu, where Gregor Mendel grew up, or Sigmund Freud, the philosopher Edmund Husserl, the composer Gustav Mahler, and Franz Kafka of course in Prague… So I think that these mixed nations are very fruitful ground for raising interesting people.”

Placzek’s earliest penchant was for language, and he spoke around ten fluently. He was well-conversant in matters of culture throughout his life, and he was a jovial and sociable person. When he completed his studies in physics in Prague and Vienna with resounding success, his intellectual versatility found him a warm welcome among some of the greatest scientists in history: Werner Heisenberg, Enrico Fermi, Otto Frisch, Robert Oppenheimer, Edward Teller, and of course, the father of quantum mechanics Niels Bohr, in whose Copenhagen research centre Placzek spent six years.

“He called Placzek the “ever-stimulating Bohemian”. Because they were two different types of people, I think, the best combination for theoretical physics: one who has new ideas - maybe crazy ideas - and on the other hand someone like Placzek, who was very critical. And such a combination of authors is excellent. Placzek, through his criticism, was able to stimulate Bohr to obtain new results that would not have been obtained without it.”

He also had a critical mind for politics. First a radical leftist and later a staunch critic of the radical left, Placzek’s political views were mutable but always strong, it seems. In 1934, he insisted to his friends and colleagues that Hitler would start a war within five years. He tried to persuade his family to leave, but they didn’t believe him until it was too late.

“During the second war, all of them died. They were simply exterminated, his parents. His brother committed suicide after trying to emigrate to England in ‘39. He asked his people from the cash office to give him money to fly to London, and they – suddenly - turned out to be Nazis; they had been his friends but now they were Nazis. So they refused to give him his own money. And he went into the next room and he shot himself.”

Placzek’s parents were apparently killed in Auschwitz; his sister ended in the Gulag and was never heard from again. After paying a visit to Moravia in a final attempt to get them to emigrate with him, Placzek moved to America along with much of Niels Bohr’s Copenhagen group.

“Bohr decided to move the Jewish part of his school, his group, to the United States. Niels Bohr was a powerful professor, they were all young – 25 to 30 years old – Niels Bohr was already in his mid-50s, or something like that, so he was able to move these endangered personalities to the United States.”

In America, first at Princeton, Placzek continued his work with the greatest minds of the golden age of physics and they were strongly influenced by him, professionally and intellectually. He was said to be single-handedly responsible for converting many a colleague from their communist streaks, such as Robert Oppenheimer (though seeing the light failed to save him from the Red Scare inquisitions). His great talent it seems was in noticing the details that other people, even the sharpest minds on the planet, missed.

“His main benefit was his criticism of other people’s work. They wrote papers and he would read them and say ‘no, no, no, not this, not this’, he was very critical, and he was of great help to many people just in finding their errors, or their misconceptions or bad formulations. So he was sought after, looked to, for his criticism, and the papers that passed through his filter were of high quality.”

Georg Placzek’s work was primarily on light and its dispersion, but his greatest impact regarded the neutron. He was taken on board to work on the Manhattan Project, the race to build an atomic bomb before the Germans, because he had the highest credentials. Niels Bohr credited him with clarifying how the atom is split, Otto Frisch with the giving the fundamental idea for proving nuclear fission - all of which added up to one of the most important moments in human history.

The geniuses assembled in the desert in goggles and sunscreen on the morning of the Trinity test recorded the tremendous emotions of the moment as the countdown was read out (Tchaikovsky’s Nutcracker Suite crackling in the background due to radio interference from a storm) and they first witnessed the awful power of their creation.

As the head of the Manhattan Project’s theoretical department, Placzek was there among the 260 observers, but there is no record of his thoughts or impressions. He tended to stay in the shadows of things, seemingly having little need for public recognition. Almost unthinkable for a scientist, he published little and was offered and spurned co-authorships of even important theories he had been key to refining.

“And so there is a suspicion that I have found also in literature that the main contribution to many papers of famous people was thanks to Placzek’s criticism. Many of his results remained unpublished. He was able to calculate, to obtain the interesting results, but then to sell it – to write an article – was extremely difficult for him. He would start writing, then not be satisfied and start again…”

This is why an important scientist remained unsung for decades after his death – the circumstances of which, incidentally, remain as furtive as the details of much of his life. In the early 1950s Placzek began spending more time in Europe and in 1955 he planned to spend the academic year in Rome. In October of that year, he left for a weekend and gave no address, and was never seen alive again.

“He died suddenly, nobody knows why. He always seemed to be a very happy person, but there is concern that he committed suicide – no one knows, but that’s what I was told by people who knew him very well. Maybe suicide was inherited in his family. But I was told he had high blood pressure, and the only medicine available for that condition in the 1950s was something that caused depressive side effects.”

Georg Placzek has only come to be a well-known name in recent years, and the years to come may add to that renown, as time uncovers more about the contributions this great scientist made to physics and to history.