Lilli Hornig

Born in Ústí, Lilli Hornig, together with the Brno physicist Georg Placzek, was the only Czech to have played a part in the development of the atom bomb in the secret “Manhattan Project”. As a chemist she was involved in research on the plutonium bomb which devastated Nagasaki on 9th August 1945. Her husband Donald Hornig was one of the main creators of the weapon. 

Lilli Hornig was born in 1921 in Ústí nad Labem into the Schwenk family. The Ústí part of her life, however, was short, as in 1929 the Schwenks moved to Berlin; with their Jewish roots, they then moved overseas in 1933.
Lilli inherited her talents from her father Erwin Schwenk, who worked from 1916–1929 as a researcher for the Association for Chemical and Metallurgical Production in Ústí n. Labem [originally Österreichischer Verein für Chemische und Metallurgische Produktion].
Lilli studied at Harvard, where she met and went on to marry Donald Hornig in 1942. In the spring of 1944 her husband was offered work on the “Manhattan Project”, and so he and his wife moved to Los Alamos in New Mexico. There were no plans to include Lilli in the research, but as an emancipated academician she refused to take a lesser job as a secretary. So, first of all she worked on plutonium research, but due to the risk of her becoming infertile she was then transferred to the explosives department, where she came up with a method of compressing plutonium in a chemical explosion to increase the effect of the atom bomb. Her husband was part of the close team around the head of the project, Robert Oppenheimer. When the world’s first nuclear explosion, called “Trinity”, took place on 16th July 1945 in New Mexico, as one of its main creators Don had to observe the impact of the bomb from the closest bunker, 16 kilometres from the epicentre. Lilli drove into the mountains two hundred kilometres away. “This mushroom went up in front of us... We were all shaken up. It was fantastic I remember these boiling clouds and vivid colors like violet, purple, orange, yellow, red, just everything... It sucked in the centre and unfolded like flowers,” she said, describing the historical moment. After this experience she joined the scientists petitioning for the bomb to be first used on non-human targets as a deterrent. The bomb she helped to create brought apocalypse to the Japanese town of Nagasaki on 9th August 1945.
After the surrender of Japan she completed her doctorate at Harvard which had been interrupted by the war and embarked on an academic career. She was closely involved in the women’s emancipation movement. She died at the end of 2017 at the age of 96. 

KRSEK, M.: Neznámí hrdinové mluvili i německy. Praha 2018.
Plutoniová dáma se vrací domů. URL: http://www.muzeumusti.cz/c2226/Plutoniova-dama-se-vraci-domu/ [20. 7. 2021].

Lilli Hornig spent her early childhood in Ústí nad Labem (mid 1920s). (Author: public domain)

Lilli Hornig was not only an important scientist but active in the women emancipation movement as well. (Author: courtesy of the author)

Lilly Hornig at the time of her work on the Manhattan Project. (Author: public domain)