Denmark - Conditions of Life - Research
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3.Conditions of Life
3.9 Research
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Niels Henrik David Bohr
Tycho Brahe
Ole Rømer
Niels Stensen
Bengt Strömgren
Christian Jürgensen Thomsen
Hans Christian Ørsted
Niels Henrik David Bohr, 1885-1962. Niels Bohr was the son of the physiologist Christian Bohr, in whose private laboratory he carried out his first and only experimental work on surface tension, which brought him the gold medal of the University of Copenhagen. His doctoral dissertation from 1911, on the other hand, was purely theoretical. Cooperation with Rutherford in Manchester was the start of an unusually fruitful process, which over the years produced four fundamental contributions to scientific knowledge, all of which concerned quantum mechanics and its application to atomic and nuclear phenomena. In 1913 Bohr explained the structure of the hydrogen atom and the circumstances relating to the emission and absorption of light. Further studies led to an explanation of the periodic system of elements, for which he was awarded the Nobel Prize in 1922. After this he started on the formulation of general quantum mechanics together with Heisenberg, Pauli and others. In the 1930s there followed important works on the interaction of atomic particles and matter, followed by the "liquid drop model" for the nucleus of an atom and a theory on the fission process of uranium. In 1943, during the German occupation of Denmark, Bohr went via Sweden to England and the USA, where he worked together with the physicists creating the atomic bomb. Bohr's eye for the general consequences of atomic power persuaded him to turn to Roosevelt and Churchill, but without success; and in 1950 he published an "Open Letter to the United Nations", in which the idea of an "open world" with the free exchange of knowledge was propounded as a necessary condition for peace. Bohr's status as one of the unchallenged pioneers of physics led already in 1920 to the establishment of the Copenhagen University's Institute for Theoretical Physics (since 1965 known as the Niels Bohr Institute), which attracted researchers from all over the world. Bohr's own understanding of quantum mechanics became known as the Copenhagen Interpretation, and his thoughts on "complementarity" between apparent opposites (first used on waves and particles) has since been used as a philosophical tool far beyond the field of physics.
Olaf Pedersen
Niels Bohr Archive
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Tycho Brahe, 1546-1601. With his discovery of "the new star" in 1572, Tycho Brahe became famous as an astronomer throughout Europe. To secure him for Denmark, Frederik II endowed him in 1576 with the island of Hven, where he gradually built up a research institution of an entirely new kind. This comprised the extensive castle of Uranienborg, the observatory of Stjerneborg, a paper mill and printing press, and a workshop for making instruments, by means of which Tycho Brahe gradually increased the accuracy of his observations to the limits of what the naked eye could see. He rejected all previous observations as dubious, and aimed to "reconstruct astronomy" by personally surveying all heavenly phenomena from scratch. This work continued until 1597, when after a quarrel with Christian IV Tycho Brahe left Denmark. He took all his equipment with him and ended his days as a "mathematician" at the court of the Emperor Rudolph II of Vienna.
Among Tycho Brahe's many results was the demonstration in 1577 that a comet was a heavenly body and not an atmospheric phenomenon as previously assumed. In addition came the discovery of two hitherto unknown "anomalies" in the movements of the moon and a catalogue containing the positions of 1000 fixed stars. He himself did not manage to utilize his many planetary observations, but in 1600 he handed a series of observations of Mars to Johannes Kepler, who used them in deriving his three fundamental laws for the movement of the planets in general. Tycho Brahe's cosmology with the Earth at the centre of a system, circled by the Sun, around which the other planets rotate, was widely used in the 17th century as an alternative to the Copernican system condemned by the Church.
Olaf Pedersen
Vetenskapsakademinen, Stockholm/Lars Falck
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Ole Rømer, 1644-1710. As a student living in Rasmus Bartholin's house, Rømer was given the task of preparing an edition of Tycho Brahe's works, for which reason he accompanied the French astronomer Jean Picard to Paris in 1672. Here, in 1676, he demonstrated that certain irregularities in the timing of the eclipses of the moons of Jupiter could be explained as the result of light's "hesitating" or its finite velocity, which has since emerged as the most fundamental natural constant in physics. After his return to Denmark in 1681 he reorganised the observatory in the Round Tower at the same time as undertaking various public duties which included surveying the Danish road network, establishing a unified system of weights and measures, and introducing the Gregorian calendar in 1700. Long before Celcius, Rømer was using the freezing and boiling points of water as natural fixed points on thermometers. In his private observatories, Rømer first developed the transit instrument and then the meridian circle, which 100 years later became astronomy's most accurate instrument for measuring position. Apart from a notebook called Adversaria and three days' observations from 1706, all Rømer's scientific notes were lost in the Fire of Copenhagen in 1728.
Olaf Pedersen
Unknown artist, Copenhagen Police
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Niels Stensen (Nicolaus Steno), 1638-86. In 1660, after spending three years studying medicine in Copenhagen, Stensen went to Amsterdam, where he made his first anatomical discovery: the duct between the auricle gland and the oral cavity (ductus stenonis). In succeeding years in Leiden he explained the principal features of the physiology of the glands, at the same time as his contributions to embryology and comparative anatomy made him a researcher of European standing. Most discussed was his demonstration that the heart is neither more nor less than a muscle.
After failing to be appointed professor in Copenhagen in 1664, he spent a year in Paris, where in a famous lecture on the anatomy of the brain in 1665 he demonstrated the incorrect anatomical basis of cartesianism. In his study of muscular physiology he was the first to argue that a mathematical description is also necessary in biology. After being employed at the Medici court in Florence, he converted to Catholicism in 1667. He continued his scientific work with outstanding results, summing them up in his dissertation Prodomus (1669, English translation 1671), in which he laid the foundations of three new sciences. Palaeontology was given a solid foundation with the demonstration that fossils were petrified remains of living creatures. As fossilised shark's teeth were found in mountains, these must once have been covered by the sea, so that the earth's crust must have undergone profound changes over the ages. By means of field work Stensen succeeded in demonstrating and interpreting the geological stratification of Tuscany, whereby the principles of historical geology were established. Finally, crystallography was given a scientific foundation through Stensen's demonstration that crystals grow when materials are deposited on their outer surfaces, the mutual angles of which remain constant during this process.
In 1672 Stensen returned to Copenhagen to a newly-established post as Royal Anatomist; he attracted many students from the university, which on several occasions invited him to carry out public dissections, but bypassed him in 1674 and appointed the 19-year-old Caspar Bartholin to a vacant Chair of Anatomy. This was partly responsible for Stensen's decision to return to Florence, where he was ordained priest in 1675 in order to devote the rest of his life to the service of the Church. In 1677 he was consecrated bishop in Rome, after which he worked for the rest of his life among the widely dispersed Catholics of northern Germany and as a consequence of his vow of poverty came to live in extreme need. After an unheeded visit to Copenhagen in 1685 he died the following year in Schwerin, from where his body was transported to Florence to be buried in the Medici church of San Lorenzo. He was beatified by Pope John Paul II in 1986.
Olaf Pedersen
Geologisk Institut/Ole Bang Berthelsen
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Bengt Strömgren, 1908-87. Bengt Strömgren was the child prodigy of Danish science, who even while no more than a boy published articles on classical astronomy, and was awarded a doctorate before reaching the age of 21. He then turned to the new experiments in astrophysics aimed at applying quantum mechanics to the structure of the stars. This led to his epoch-making works on the atmospheres of the stars and their chemical constitutions and on hydrogen in the space between them. In 1950 Strömgren left his professorial chair in Copenhagen to work for the next 17 years in the USA as Director of the Yerkes Observatory and later as researcher at the Institute for Advanced Study in Princeton. His main interest was now to study the structure and development of our galaxy by using the ever-increasing amount of data concerning the movements, ages and chemical compositions of the stars. Strömgren was not only a leading figure in astrophysics, but he also made important contributions to practical astronomy, including the calculation of mirrors and object lenses. In addition he was one of the first to attempt photoelectric registration of stars, a principle which is now used to perfection in the Carlsberg meridian circle on La Palma. The joint European observatory in La Silla in the southern hemisphere benefited from his initiatives in its early years.
Olaf Pedersen
Polfoto
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Hans Christian Ørsted, 1777-1851. Ørsted was the son of an apothecary and himself a trained pharmacist. His first publication, in 1797, was a treatise on amniotic fluid, and two years later he was awarded a doctorate for a dissertation on Kant's philosophy. After 1800 he studied the new galvanism, spending 1801-04 in Germany, where he worked with J.W. Ritter and was fascinated both by J.J. Winterl's remarkable chemical philosophy and by Fichte's ideas on universal reason and the unity of natural forces. On the other hand he was put off by French mathematical physics. In 1806 he was the first to be appointed Professor of Physics in Copenhagen since 1732, and from 1815 to his death he was Secretary to the Royal Danish Academy of Sciences and Letters. His discovery of the magnetic effect of electrical currents in 1820 was immediately recognised as an epoch-making advance, although he left further work on electromagnetism to others. He himself studied the compressibility of water and also succeeded in producing pure aluminium. After 1820 he was the determining influence on research policy in Denmark. In 1824 he founded the popular Society for the Propagation of the Natural Doctrine, and in 1829 established the Technical University of Denmark, where engineering received a scientific foundation.
Olaf Pedersen
Royal Library
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