Atle Selberg

Atle Selberg
Born	(1917-06-14)14 June 1917 Langesund, Norway
Died	6 August 2007(2007-08-06) (aged 90) Princeton, New Jersey, United States
Nationality	Norwegian
Alma mater	University of Oslo
Known for	Critical line theorem Local rigidity Parity problem Weakly symmetric space Chowla–Selberg formula Maass–Selberg relations Rankin–Selberg method Selberg class Selberg's conjecture Selberg's identity Selberg integral Selberg trace formula Selberg zeta function Selberg sieve
Spouse	Hedvig Liebermann
Awards	Abel Prize (honorary) (2002) Fields Medal (1950) Wolf Prize (1986) Gunnerus Medal (2002)
Scientific career
Fields	Mathematics

Atle Selberg (14 June 1917 – 6 August 2007) was a Norwegian mathematician known for his work in analytic number theory and the theory of automorphic forms, and in particular for bringing them into relation with spectral theory. He was awarded the Fields Medal in 1950.

Early years

Selberg was born in Langesund, Norway, the son of teacher Anna Kristina Selberg and mathematician Ole Michael Ludvigsen Selberg. Two of his three brothers, Sigmund and Henrik, were also mathematicians. His other brother, Arne, was a professor of engineering. While he was still at school he was influenced by the work of Srinivasa Ramanujan and he found an exact analytical formula for the partition function as suggested by the works of Ramanujan; however, this result was first published by Hans Rademacher. During the war he fought against the German invasion of Norway, and was imprisoned several times. He studied at the University of Oslo and completed his Ph.D. in 1943.

World War II

During World War II, Selberg worked in isolation due to the German occupation of Norway. After the war his accomplishments became known, including a proof that a positive proportion of the zeros of the Riemann zeta function lie on the line $\Re (s)={\tfrac {1}{2}}$.

After the war, he turned to sieve theory, a previously neglected topic which Selberg's work brought into prominence. In a 1947 paper he introduced the Selberg sieve, a method well adapted in particular to providing auxiliary upper bounds, and which contributed to Chen's theorem, among other important results.

In 1948 Selberg submitted two papers in Annals of Mathematics in which he proved by elementary means the theorems for primes in arithmetic progression and the density of primes. This challenged the widely held view of his time that certain theorems are only obtainable with the advanced methods of complex analysis. Both results were based on his work on the asymptotic formula

$\vartheta \left(x\right)\log \left(x\right)+\sum \limits _{p\leq x}{\log \left(p\right)}\vartheta \left({\frac {x}{p}}\right)=2x\log \left(x\right)+O\left(x\right)$

where

$\vartheta \left(x\right)=\sum \limits _{p\leq x}{\log \left(p\right)}$

for primes $p$. He established this result by elementary means in March 1948, and by July of that year, Selberg and Paul Erdős each obtained elementary proofs of the prime number theorem, both using the asymptotic formula above as a starting point. Circumstances leading up to the proofs, as well as publication disagreements, led to a bitter dispute between the two mathematicians.

For his fundamental accomplishments during the 1940s, Selberg received the 1950 Fields Medal.

Institute for Advanced Study

Selberg moved to the United States and settled at the Institute for Advanced Study in Princeton, New Jersey in the 1950s where he remained until his death. During the 1950s he worked on introducing spectral theory into number theory, culminating in his development of the Selberg trace formula, the most famous and influential of his results. In its simplest form, this establishes a duality between the lengths of closed geodesics on a compact Riemann surface and the eigenvalues of the Laplacian, which is analogous to the duality between the prime numbers and the zeros of the zeta function.

He was awarded the 1986 Wolf Prize in Mathematics. He was also awarded an honorary Abel Prize in 2002, its founding year, before the awarding of the regular prizes began.

Selberg received many distinctions for his work in addition to the Fields Medal, the Wolf Prize and the Gunnerus Medal. He was elected to the Norwegian Academy of Science and Letters, the Royal Danish Academy of Sciences and Letters and the American Academy of Arts and Sciences.

In 1972 he was awarded an honorary degree, doctor philos. honoris causa, at the Norwegian Institute of Technology, later part of Norwegian University of Science and Technology.

Selberg had two children, Ingrid Selberg and Lars Selberg. Ingrid Selberg is married to playwright Mustapha Matura.

He died at home in Princeton, New Jersey on 6 August 2007 of heart failure.

Selected publications

• Atle Selberg Collected Papers: 1 (Springer-Verlag, Heidelberg), ISBN 0-387-18389-2
• Collected Papers (Springer-Verlag, Heidelberg Mai 1998), ISBN 3-540-50626-8

Further reading

• Albers, Donald J. and Alexanderson, Gerald L. (2011), Fascinating Mathematical People: interviews and memoirs, "Atle Selberg", pp 254–73, Princeton University Press, ISBN 978-0-691-14829-8.
• Baas, Nils A.; Skau, Christian F. (2008). "The lord of the numbers, Atle Selberg. On his life and mathematics". Bull. Amer. Math. Soc. 45 (4): 617–649. doi:10.1090/S0273-0979-08-01223-8. Interview with Selberg
• Hejhal, Dennis (June–July 2009). "Remembering Atle Selberg, 1917–2007" (PDF). Notices of the American Mathematical Society. 56 (6): 692–710.
• Selberg (1996). "Reflections Around the Ramanujan Centenary" (PDF).

External links

• Atle Selberg at the Mathematics Genealogy Project
• Atle Selberg at the Encyclopædia Britannica
• O'Connor, John J.; Robertson, Edmund F., "Atle Selberg", MacTutor History of Mathematics Archive, University of St Andrews
• Atle Selberg Archive webpage
• Obituary at IAS
• Obituary in The Times
• Atle Selbergs private archive exists at NTNU University Library