Victor Francis Hess began his career with a short stint at the Physics Institute of Vienna. Here he worked under Professor Von Schweidler, who was the first to introduce young Hess to the new discoveries that were being made in the field of radioactivity.
In 1911, he joined Institute for Radium Research, a newly opened research institute under Austrian Academy of Sciences. There he worked under Stefan Meyer, an Austrian Scientist involved in research on radioactivity and also under Franz Exner, a pioneer in the study of radiation.
Under them, he began his research on gamma rays. At that time it was believed that air was slight conductor of electricity because of ionization of gamma rays. It was assumed that the earth was the source of this radiation. But, preliminary findings suggested that the ionization increased with altitude and so the earth could not be the source.
A number of renowned scientists began to experiment on this. Hess first designed a new device that was far more precise than previously used. He then went up in balloons to measure the degree of ionization, once in 1911 and seven times in 1912 and once in 1913. Each time, he measured the radiation systematically.
Hess found that the level of radiation decreased up to an altitude of one kilometer and then began to increase. What is more, the radiation is almost double at an altitude of 5 km in comparison with the level of radiation at sea level. Therefore, the earth could not be the source.
Hess went up in the balloon during the day as well as in the night. One of these ascents was also undertaken during total eclipse of the sun. He found little difference in the readings. So he concluded that the sun could not be the source of the ionization either.
Finally in 1912, he concluded that unknown ray with high penetrating capability enters the earth's atmosphere from space and that ray is the cause of such ionization. Hess published the result of his work in the Proceedings of the Viennese Academy of Sciences.
His findings were confirmed much later in 1925 by American physicist Robert Andrews Millikan. It was Millikan, who named the ray, ‘cosmic ray’. Meanwhile Hess continued teaching at Institute for Radium Research and at the same time carried on his research work.
In 1920, he was appointed Associate Profess at the University of Graz. In 1921, he took leave of absence and went to the USA. There he worked for two years with United States Radium Corporation (New Jersey) and US Bureau of Mines (Washington DC).
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Hess rejoined the University of Graz in 1923 and served there till 1931. In 1925 he became the Ordinary Professor of Experimental Physics at the University.
From 1931 to 1937, he served as the Professor Director at the Institute of Radiology under University of Innsbruck.
Hess was married by then and his wife was a Jew. He had also been a representative of the sciences in the independent government of Chancellor Kurt von Schuschnigg. Therefore, in 1937, as Germany occupied Austria, he was warned that if he stayed back in Austria he would be arrested and sent to concentration camp.
To avoid persecution by the Nazis, he first went to Switzerland. Within a month, his arrest warrant was issued in Austria. Therefore, he decided to relocate to the USA, where his wife’s son from her first marriage used to live.
He finally immigrated to the USA in 1938 with his wife. In the same year, he joined Fordham University as Professor of Physics and continued with his research.
In 1946, he together with Paul Luger of Seattle University conducted the first tests for radioactive fallout of Hiroshima bombing in the United States.
By 1947, Hess worked out "an integrating gamma-ray method" by which minute amounts of radium in the human body could be detected. As a result, detection of radium poisoning at an early stage became feasible.
In 1955, he was asked by the United States Air Force to study the effect of nuclear test in terms of radioactivity. Hess differentiated between natural and artificial radiation and established that traces of artificial radiation can be determined in the atmosphere.
He taught at the Fordham University for twenty years. He retired from there in 1958, but continued with his research work. Throughout his career, he published sixty papers and quite a few books. ‘Die Wärmeproduktion des Radiums’ (The heat production of radium), written in 1912 was his first published book.
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Awards & Achievements
In 1919, he was awarded with the Ignaz Lieben Prize by the Austrian Academy of Sciences for the discovery of cosmic rays.
In 1936, Victor Francis Hess jointly received Nobel Prize in Physics for his discovery of cosmic radiation.
In 1932, Hess received Abbe Memorial Prize and the Abbe Medal of the Carl Zeiss Institute in Jena.
In 1959, he was honored with Austrian Decoration for Science and Art by the government of Austria.
Personal Life & Legacy
In 1920, Victor Francis Hess married Marie Bertha Warner Breisk. Since she was a Jew, Hess had to relocate to the USA in 1938 on the wake of persecution by the Nazis. He lived there till the end of his life.
In 1944, Hess became a naturalized citizen of the USA. Marie Bertha died of cancer in 1955. In the same year, he married Bertha’s nurse Elizabeth M. Hoenke. The couple remained married until his death in 1964. He did not have any children.
Towards the end of his life Hess was afflicted with Parkinson’s disease. He died from it on 17 December 1964, in Mount Vernon, New York.
Domenico Pacini, a contemporary of Hess, also undertook extensive experiment on cosmic rays. However, instead of going up in a balloon, he went under the sea. He put his instrument in a copper box and then placed it the Bay of Livorno.
The radiation measured at the bottom of the sea was much less than that found on the surface. So he concluded that earth’s crust could not be the source of the cosmic rays. Since both the scientists knew about each other’s work, it was argued that Hess should not get the sole credit of discovering the cosmic ray.
Unfortunately, Pacini passed away in 1934, the year it was decided that Nobel Prize should honor the discoverer of the cosmic rays. Since this prize cannot be awarded posthumously Hess alone was honored for the discovery of cosmic rays.