Slovenian Scientists

Janez Vajkard Valvasor (1641 – 1693)

Janez Vajkard Valvasor (1641 – 1693)

Baron Janez Vajkard Valvasor is considered the founder of scientific literature on Slovenian territory. His fundamental, and today still most esteemed work, is The Glory of the Duchy of Carniola, which he finished four years before his death. It is a rich encyclopaedic work that was written in German so that more people could understand it, and includes an incredible amount of data on the land and history of the Slovenian people. In this work, with its scientific and technological bibliography completed by many others, Valvasor included numerous inventions, designs and descriptions, which were, in fact, beyond their time. Among them are sketches and a description of the natural mechanism of the intermittent Lake Cerkniško (which also brought him membership of the Royal Society), the design of a tunnel under the Ljubelj mountain pass which he addressed to the Emperor’s office, a method of casting sculpture, and the first maps of Slovenia and neighbouring territories. 

The Glory of the Duchy of Carniola

The Glory of the Duchy of Carniola  is quite demanding reading. Not because of the German or archaic language, but because of the amount of data included in its 15 volumes totalling 3,532 pages. We quickly realise that the author was a polymath. He had a great knowledge of numerous details of particular sciences (historiography, geography, and generally in the arts and natural sciences), which is evident from the Glory itself. In addition, he not only recorded stories and historical events, but also successfully explored and presented new knowledge. In this respect, he also turned away from alchemy, although he states that he was at first even involved in certain experiments that failed.

This was a period when, due to various discoveries, alchemy had to make way for advancing natural science. It was a time when, in addition to alchemy, a mysterious, occult, but at the same time quite frequent, theme was witchcraft. Some people then still believed in the existence of witches. Valvasor was not among them. He explained the behaviour of 'witches' as resulting from certain drugs which they took. His studies, travels and scientific explanation of the world demanded a lot of time, energy and money.

The Glory of the Duchy of Carniola, his life work, which secured his place in history, finally exhausted him both physically and financially. Because of his love for science, exploration and writing, he had to sell off all his property, including Črni potok Castle, Bogenšperk near Litija, and Lichtenberg. From today's perspective it is perhaps the most sad that Valvasor had to sell his extensive book and graphics collection (1,530 notebooks) to the Bishop of Zagreb. The story of an exceptional rise which is granted only to the select few was followed by impoverishment at the end of his life. The Slovenian polymath, inventor and writer died in Krško, in mid-September 1693. Until the replacement of the tolar, his image, with a pair of compasses and a topographical background, adorned the twenty tolar note. Since 1903, a commemorative bronze statue double his size and weighing one and a half tonnes has stood in front of the National Museum

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Herman Potočnik Noordung (1892 – 1929)

Potočnik's Space Station (illustration (c) by Simon Zajc). Source:

“Since the beginning of time, mankind has considered it as an expression of its Earthly weakness and inadequacy to be bound to the Earth, to be unable to free itself from the mysterious shackles of gravity. Not without good reason then has the concept of the transcendental always been associated with the idea of weightlessness, the power 'to be able freely to rise into the sky'. And most people even today still take it as a dogma that it is indeed unthinkable for Earthly beings ever to be able to escape the Earth. Is this point of view really justified?” This daring thought was written by the pioneer of rocket and space science Herman Potočnik Noordung in his book The Problem of Space Travel. It was published in German, in 1928, and in the decades that followed, it became the standard textbook on questions of space technology for Russian, German and American experts.

Herman Potočnik was born on 22 December 1892 in Pula, then part of the Austro-Hungarian Empire. His father was a naval officer. After his death, when Herman Potočnik was only two years old, he moved with his mother to Maribor. He also spent his childhood years in Vitanje, where there is a memorial room dedicated to him. But there is a shortcut for anyone wishing to pay their respects to the genius in their thoughts: the view of the starry night sky, where we can see certain moving objects – satellites. The geo-stationary satellite and the manned space station are two of the most well-known of Potočnik’s ideas which have come about. He was so far ahead of his time that he was considered a dreamer in scientific circles. No wonder, for there were carriages on the paved streets when Potočnik wrote that an observatory would be "located far above the atmosphere, in empty space: a space station at an altitude of 35,900,000 meters above sea level…If this ‘space station’ had been established at the meridian of Berlin, for example, it could continually be seen from Berlin at that position in the sky where the sun is located at noon in the middle of October." It was too much for that time, but enough to make him immortal. The famous Arthur C. Clarke referred to Potočnik’s work as an influential factor. Satellites are today already orbiting the Earth, but the space station is still far from complete; according to his descriptions it is supposed to consist of a habitat wheel, an observatory, and a machine room. This was depicted by Stanley Kubrick in his film vision 2001: A Space Odyssey. Because the habitat wheel rotates around its axis, it creates artificial gravity. In his book, Potočnik gave numerous other practical instructions for life in a weightless state: the space suit, writing instruments, special bottles for drinking and others. “To sleep, we do not have to lie down first, however; we can take a rest in any bodily position or at any location in the room.”

He was thinking about space until the end. He fought tuberculosis and eventually won. He lived to see the book being published, and died in Vienna on 27 August 1929. Except for his book, there are no remains of his earthly existence. His personal belongings have disappeared; the house where he lived was demolished for the inner Vienna bypass; his grave dug up…His memorial is floating in orbit above the Earth.

Friderik Pregl (1869 – 1930)

In a speech on 10 December 1923, Professor Olof Hammarsten, the Chairman of the Nobel Committee for Chemistry at the Swedish Academy of Sciences pointed out the importance of Pregl’s success in the improvement of existing methods of quantitative organic microanalysis. A professor at Graz University, Friderik Pregl thus became the first and only Slovenian Nobel Prize Laureate. His success was revolutionary for the basic beginning of chemical experiments. After his discoveries, smaller traces would suffice for chemical analysis. According to Dr Janez Jamnik, the president of the Scientific Council of the National Institute of Chemistry, Dr Pregl was the founder of modern organic microanalysis. Thanks to his method, the minimum of substance necessary for research was 10 to 100 times smaller. This step was crucial not only for chemistry, but also medicine and biology.

In his time, conditions for education and later research were better in Austria, so Pregl followed the example of the physicist Jožef Stefan, another Slovene who studied and worked in a German-speaking environment. This is why his name appears as Fritz Pregl, as he was known in Austria, on the official web site of the Nobel Foundation. But, on the other hand, there is the incontestable biographical fact that he was born in Ljubljana, on 3 September 1869. A commemorative bust was installed in the façade of the house near Križanke where he was born. He also went to primary and secondary school in Slovenia’s capital. After his father’s death, he moved with his mother to Graz, a place crucial for his further education and also the place where he died, on 13 September 1930.

Friderik Pregl was esteemed not only for his research work, but was one of the more popular professors among the students. His popularity and general modesty led to an unusual celebration after he was awarded the Nobel Prize. On his return to the University, the celebration was organised by the students themselves.  

Pregl began working on the modernisation of organic microanalysis in 1909, when he faced problems because the samples used in studying the composition of bile acids were too small. He was forced to think about improving the procedures, as well as the instruments. Because his enthusiasm for research had led him into learning certain skills (glassblowing, carpentry, locksmithing), he was able to resolve certain problems with the instruments. He constructed a laboratory device that was, in addition to its sensitive analytic scales (weighing within an accuracy of ± 0.001 mg), crucial for his scientific breakthrough. WWI interrupted the development of the method, but it advanced quickly afterwards. In future years, his method of microanalysis enabled achievements in the research of bile acids, enzymes and vitamins. Friderik Pregl became the eternal bridge between the first steps and the modern age of this analytic method. His spirit was also invoked by the research organisation of the National Institute of Chemistry where, in 2007, at the celebration of their 60th anniversary, they awarded, for the first time, the prestigious Pregl Award for outstanding achievements in the field of chemistry. 

Jožef Stefan (1835 – 1893)

The Jožef Stefan Institute, the largest Slovenian research institution in the area of the natural, mathematical,technical, medical

How hot is the surface of the Sun? Around 5430 degrees Celsius, as first correctly calculated by Slovenian physicist Jožef Stefan using his physical law. Not only was he the first to give a plausible answer, he was also the first and so far the only physicist of Slovenian descent to contribute their name to a fundamental law of physics. In 1879, Jožef Stefan discovered the law of heat radiation, which five years later was theoretically derived from thermodynamic laws by his student Ludwig Boltzmann. Today, the law stating that the total energy radiated from a blackbody is proportional to the fourth power of the absolute temperature of that body is named after both men, but in the correct order: the Stefan-Boltzmann Law.

Jožef Stefan was born on 24 March 1835 to a Slovenian family in Austrian Carinthia, in Sveti Peter, a village now incorporated into Klagenfurt. Already in primary school, he had the will and love of learning that would help him overcome adverse circumstances. In high school he showed his knowledge of the humanities by writing poetry and prose, while at university, he had begun writing popular science articles. At 22, he was already a high school teacher; at 23 he was awarded his PhD; and five years later he was a university teacher, the youngest professor in Austria-Hungary. Therefore, it is not surprising that at barely thirty he was elected to the Austrian Academy of Sciences and became director of the Physical Institute. He achieved his success among the cream of intellectuals and scholars of Vienna, the capital at the time and the place where worked until his death. His spent his life between the doors to his apartment, the university and the laboratory; where he studied all fields of physics, including mechanics, acoustics, magnetism and electricity. Such a way of life in a German-speaking environment led to two things. Although he was born to Slovenian parents and in his youth wrote his name as Jožef Štefan, he later dropped the caron in his surname. He was dedicated to ceaseless research and work and married quite late, only a year before his death. He died in Vienna on 7 January 1893.

In his honour in 1952, the central Slovenian scientific research institute in Ljubljana was named the Jožef Stefan Institute. To mark his birth an event called Stefan Days is organised and, and up to three Jožef Stefan Golden Emblem Prizes are awarded for excellence in science.