Thomas Clausen was a Danish mathematician and astronomer. His work was recognized by many of the top scientists of the day.
Background
Clausen was born on January 16, 1801, in what is now Duchy of Schleswig, Denmark, the oldest of eight children. His parents were Claus Clausen, the son of Johan Clausen and Sille Jacobsdatter, and Cecilia Rasmusten, the daughter of Thomas Rasmussen and Marike Peters. The family was poor farmers and Thomas worked on the farm from a young age.
Education
When he was twelve years old, Thomas began working for the priest in the neighboring parish, Georg Holst. Thomas was employed to look after cattle, but Holst quickly realized that he was very intelligent so while still working with the cattle, Thomas also attended the local school. Despite being unable to read or write when he started his lessons, Thomas quickly progressed showing a remarkable aptitude for mathematics. Holst was an amateur astronomer and mathematician and was able to teach Clausen these subjects as well as Latin and Greek. Clausen also studied several languages on his own, in particular French, English, and Italian. He performed so well in his final school examinations that Holst recommended him to Heinrich Christian Schumacher, the professor as astronomy at the University of Copenhagen.
Career
Upon Holst's recommendation, H. C. Schumacher made Clausen his assistant at his Altona observatory in 1824. Clausen, a very individualistic man, had a falling out with his superior; and at the end of 1828, he moved to Munich as the appointed successor to Fraunhofer at the Joseph von Utzschneider Optical Institute. He held this position in name only, however; Utzschneider allowed Clausen to devote himself completely to his mathematical and astronomical calculations and publications, which soon gained him the attention and recognition of such authorities as Olbers, Gauss, Bessel, Steinheil, Hansen, Crelle, A. von Humboldt, Arago, and W. Struve.
In the middle of 1840, after a severe bout with mental illness, Clausen returned to Altona, where he spent two years in seclusion and reached the zenith of his scientific creativity. He also engaged in a mathematical argument with C. G. J. Jacobi. In 1842 he was appointed observer at the Dorpat (now Tartu) observatory, and in 1844 he took his doctorate honoris causa under Bessel. On 1 January 1866, he was made a director of the Dorpat observatory and professor of astronomy at Dorpat University. He went into retirement at the end of 1872. Clausen never married.
As a theoretician, he was less inclined toward astronomy. Gauss soon recognized the “outstanding talents” of Clausen. The Copenhagen Academy awarded him a prize for his work “Determination of the Path of the 1770 Comet.” Clausen’s approximately 150 published works are devoted to a multitude of subjects, from pure and applied mathematics to astronomy, physics, and geophysics. He repeatedly solved problems that were posed to him publicly by other mathematicians or proved theories that had been published without proof, as was the custom at that time, and corrected mistakes and errors in others. Special mention should be made in this connection of the calculation of fourteen paths of comets, as well as of the theorem, named for Staudt and Clausen, dealing with Bernoullian numbers. There is a substantial reason for believing that Clausen gained a deeper insight into the field of number theory than the material published by him would indicate.
Achievements
Membership
In 1854 Thomas Clausen received through Gauss a corresponding membership in the Gottingen Academy. In 1856 he received the same class of membership from the St. Petersburg Academy.
Royal Astronomical Society
,
United Kingdom
1848
Göttingen Academy of Sciences
,
Germany
1854
St. Petersburg Academy of Sciences
,
Russian Federation
1856
Personality
Like many astronomers of the first half of the nineteenth century, Clausen was a self-made man. He differed from most of his professional colleagues in that he was in a position to make a major contribution to those mathematical problems with which the leading intellectuals of his time were preoccupied. He possessed an enormous facility for calculation, a critical eye, and perseverance and inventiveness in his methodology.
Connections
Clausen never married and, after moving to Tartu, appears to have had no further contacts with his family back in Denmark.