Leopold Kronecker - Biography

Biography

Leopold Kronecker was born on 7 December 1823 in Liegnitz, Prussia (now Legnica, Poland) in a wealthy Jewish family. His parents, Isidor and Johanna (née Prausnitzer), took care of their children's education and provided them private tutoring at home - Leopold's younger brother Hugo Kronecker would also follow a scientific path later becoming a notable physiologist. Kronecker then went to the Liegnitz Gymnasium where he was interested in a wide range of topics including science, history and philosophy, while also practicing gymnastics and swimming. At the gymnasium he was taught by Ernst Kummer, who noticed and encouraged the boy's interest for mathematics.

In 1841 Kronecker became a student at the University of Berlin where his interest did not immediately focus on mathematics, but rather spread over several subjects including astronomy and philosophy. He spent the summer of 1843 at the University of Bonn to study astronomy and 1843-44 at the University of Breslau following his former teacher Kummer. Back in Berlin, Kronecker studied mathematics with Gustav Lejeune Dirichlet and in 1845 defended his dissertation in algebraic number theory written under Dirichlet's supervision.

After obtaining his degree, Kronecker did not follow his interest in research with an academic career path. He went back to his hometown to manage a large farming estate built by his mother's uncle, a former banker. In 1848 married his cousin Fanny Prausnitzer and the couple had six children. For several years Kronecker focused on business, and although he continued to study mathematics in his own time as a hobby and kept correspondence with Kummer, he published no mathematical results. In 1853 he wrote a memoir on the algebraic solvability of equations extending the work of Évariste Galois on the theory of equations.

His business activity allowed Kronecker a comfortable financial situation, which made it possible for him to go back to Berlin in 1855 to pursue mathematics as a private scholar. Dirichlet, whose wife Rebecca came from the wealthy Mendelssohn family, had introduced Kronecker to the Berlin elite. He became a close friend of Karl Weierstrass, who had recently joined the university, and his former teacher Kummer who had just taken over Dirichlet's mathematics chair. Over the following years Kronecker published numerous papers resulting from his previous years' independent research. As a result of this published research, he was elected a member of the Berlin Academy in 1861.

Although he held no official university position, as a member of the Academy Kronecker had the right to hold classes at the University of Berlin and he decided to do so starting with 1862. In 1866, when Riemann died, Kronecker was offered the mathematics chair at the University of Göttingen (previously held by Carl Gauss and Dirichlet), but he refused preferring to keep his position at the Academy. Only in 1883, when Kummer retired from the University, Kronecker was invited to succeed him and became an ordinary professor. Kronecker was the supervisor of Kurt Hensel, Adolf Kneser, Mathias Lerch, and Franz Mertens, amongst others.

His philosophical view of mathematics has put him in conflict with several mathematicians over the years, notably straining his relationship with Weierstrass which almost decided to leave the University in 1888. Kronecker died on December 29, 1891 in Berlin, several months after the death of his wife. In the last year of his life, he has converted to Christianity. He is buried in the Alter St Matthäus Kirchhof Cemetery in Berlin-Schöneberg, close to Gustav Kirchhoff.