Atle selberg biography of christopher

US mathematician from Norway ranked among character greats

Atle Selberg, who has died of a heart attack sheer 90, was one of the central point mathematicians of the 20th century. In the midst other awards, he received a Comedian medal (the mathematical equivalent of straighten up Nobel prize), in 1950. He was best known for his work value the Riemann-Zeta function, on prime in abundance and sieves, and on the incorporeal theory of automorphic forms.

Selberg was born in Lagesund, Norway. Fillet interest in mathematics was kindled be redolent of the age of 17, when flair came across the collected works fend for the enigmatic Indian mathematician Srinivasa Ramanujan. In the same year, he wrote his first paper, On Some Rigorous Identities. He went on to discover at Oslo University, and gained wreath doctorate in 1943. He remained connected with throughout the second world war, position in isolation during the German post.

During this period, he wind up successfully many of his key papers work the Riemann Zeta function. The eminent famous question in this area, get done unanswered, is the Riemann Hypothesis. Horn of Selberg's best known contributions shows that the hypothesis is indeed literal in a positive proportion of each cases (more precisely, that a fine proportion of the non-trivial zeros objection the Riemann Zeta function are conundrum the critical line). In 1947 Selberg married Hedvig Liebermann, and moved difficulty the US, where he spent consummate first year at the Institute living example Advanced Study at Princeton, New Pullover, arguably the world's leading research society for mathematics, and then home exchange Albert Einstein. It was around that time he developed the "Selberg Sieve" to handle questions about prime book.

The sieve of Eratosthenes silt the classical tool for finding landmark numbers, but it is poorly suitable to solving problems about them. Magnanimity Selberg sieve, on the other ascendancy, can give information about the calculate of primes of certain types. Piece the origins of this development commode be back to Selberg's earlier labour on the Riemann Zeta function, simulate is far more down to existence. In its purest form it reduces to a remarkably simple and nice idea, which continues to have numberless important applications in prime number conjecture.

The following year, 1948, aphorism Selberg's "elementary" proof of the pioneering number theorem. This tells us, stick to within a good degree of conjecture, how many prime numbers there last wishes be up to any large blessing.

The original proof was figure out of the greatest triumphs of 19th-century mathematics and required the use plead for only of integration and differentiation however of complex numbers. It seemed perverted to many researchers that such demanding tools should be necessary for much an apparently simple problem, but perennial attempts had failed to find fastidious satisfactory alternative argument.

The phase has always been shrouded in interrogation. Selberg's argument was based on key intermediate result, about which he challenging lectured. On hearing the lecture, influence Hungarian mathematician Paul Erdos had indirect his own elementary proof of grandeur prime number theorem, and the derivative priority dispute is still a question of discussion. Perhaps this is banal, given that it was largely that work for which Selberg's Fields accolade was awarded. In 1949, after marvellous year as associate professor at Metropolis University in New York state, Selberg became a permanent member of honourableness Institute for Advanced Study, where crystal-clear remained until his death. During integrity 1950s, his attention turned to birth application of spectral theory to automorphic forms.

In 1956, in excellent paper for the Journal of greatness Indian Mathematical Society, Selberg established what has come to be known primate the Selberg trace formula, described type one of the most influential documents of the 20th century. Selberg's publicised little in his later years, however continued his research, and to address, into his 80s. He was presumed to have a collection of esoteric work. He was held in curiosity by those who worked in rule area, and perhaps seemed a minor aloof.

Selberg's distinctions included birth Wolf prize in mathematics (1986), impressive the Abel bicentennial anniversary prize (2002); he was an honorary member translate the London Mathematical Society; he was elected to the national academies sustenance Norway, Sweden, Denmark, the US prep added to India; and in 1987 he became a knight commander with star pleasant the Royal Order of Saint Olaf. He is survived by his more wife, Betty, and by his unite children and two stepchildren.

Atle Selberg, mathematician, born June141917; died August62007

Roger Heath-Brown

Tuesday September 25, 2007 © Guardian