Klaus Fredenhagen (born 1 December 1947) is a German

theoretical physicist Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict natural phenomena. This is in contrast to experimental physics, which uses experi ...

who works on the mathematical foundations of

quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...

Biography

Klaus Fredenhagen was born on 1 December 1947 in

Celle Celle () is a town and capital of the district of Celle (district), Celle in Lower Saxony, in north-central Germany. The town is situated on the banks of the river Aller (Germany), Aller, a tributary of the Weser, and has a population of about ...

, a German city in

Lower Saxony Lower Saxony is a States of Germany, German state (') in Northern Germany, northwestern Germany. It is the second-largest state by land area, with , and fourth-largest in population (8 million in 2021) among the 16 ' of the Germany, Federal Re ...

. He graduated in 1976 from the

University of Hamburg The University of Hamburg (, also referred to as UHH) is a public university, public research university in Hamburg, Germany. It was founded on 28 March 1919 by combining the previous General Lecture System ('':de:Allgemeines Vorlesungswesen, ...

under the supervision of Gert Roepstorff and

Rudolf Haag Rudolf Haag (17 August 1922 – 5 January 2016) was a German theoretical physicist, who mainly dealt with fundamental questions of quantum field theory. He was one of the founders of the modern formulation of quantum field theory and he identifie ...

. In 1985 he became a

privatdozent ''Privatdozent'' (for men) or ''Privatdozentin'' (for women), abbreviated PD, P.D. or Priv.-Doz., is an academic title conferred at some European universities, especially in German-speaking countries, to someone who holds certain formal qualifi ...

and in 1990 a

full professor Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a 'person who professes'. Professors ...

at the second theory institute of the Hamburg University. Since 2013 he has been a

professor emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retirement, retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". ...

and has continued to be active in research.

Scientific career

His research interests are

algebraic quantum field theory Algebraic quantum field theory (AQFT) is an application to local quantum physics of C*-algebra theory. Also referred to as the Haag–Kastler axiomatic framework for quantum field theory, because it was introduced by . The axioms are stated in ter ...

and

quantum field theory in curved spacetime In theoretical physics, quantum field theory in curved spacetime (QFTCS) is an extension of quantum field theory from Minkowski spacetime to a general curved spacetime. This theory uses a semi-classical approach; it treats spacetime as a fixed ...

. In 1981 he proved the existence of

antiparticle In particle physics, every type of particle of "ordinary" matter (as opposed to antimatter) is associated with an antiparticle with the same mass but with opposite physical charges (such as electric charge). For example, the antiparticle of the ...

s in massive quantum field theories without using the CPT-invariance. In 1990 he and Rudolf Haag made important contributions to the understanding of the

Hawking radiation Hawking radiation is black-body radiation released outside a black hole's event horizon due to quantum effects according to a model developed by Stephen Hawking in 1974. The radiation was not predicted by previous models which assumed that onc ...

black hole A black hole is a massive, compact astronomical object so dense that its gravity prevents anything from escaping, even light. Albert Einstein's theory of general relativity predicts that a sufficiently compact mass will form a black hole. Th ...

s on a rigorous mathematical footing. In 1994, together with Sergio Doplicher and John E. Roberts, he investigated the mathematical foundations of

quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...

in terms of the quantum structure of spacetime at the

Planck scale In particle physics and physical cosmology, Planck units are a system of units of measurement defined exclusively in terms of four universal physical constants: '' c'', '' G'', '' ħ'', and ''k''B (described further below). Expressing one of ...

. In 1996, together with Romeo Brunetti, he started working on the generalization of the Epstein-

Glaser Glaser is a surname that is derived from the occupation of the glazier, or glass cutter. Notable persons with this surname * Albrecht Glaser (born 1942), German politician * Barney Glaser (1930–2022), American sociologist * Benny Glaser (born 198 ...

renormalization procedure of interacting quantum field theories in curved spacetime using techniques from the

microlocal analysis In mathematical analysis, microlocal analysis comprises techniques developed from the 1950s onwards based on Fourier transforms related to the study of variable-coefficients-linear and nonlinear partial differential equations. This includes genera ...

. He is currently working, together with

Detlev Buchholz Detlev Buchholz (born 31 May 1944) is a German theoretical physicist. He investigates quantum field theory, especially in the axiomatic framework of algebraic quantum field theory. Biography Buchholz studied physics in Hannover and Hamburg wher ...

, on a new C*-algebraic approach to interacting quantum field theories.

Honors and awards

In 1987 Klaus Fredenhagen was awarded the physics prize of the

Göttingen Academy of Sciences Göttingen (, ; ; ) is a university city in Lower Saxony, central Germany, the capital of the eponymous district. The River Leine runs through it. According to the 2022 German census, the population of Göttingen was 124,548. Overview The ...

and in 1997 he was Leibniz Professor at the

University of Leipzig Leipzig University (), in Leipzig in Saxony, Germany, is one of the world's oldest universities and the second-oldest university (by consecutive years of existence) in Germany. The university was founded on 2 December 1409 by Frederick I, Electo ...

. In December 2017 the workshop ''Quantum Physics meets Mathematics'' was held in honor of his 70th birthday at the University of Hamburg.

Selected publications

Edited books

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Articles

* * * * * * *

References

External links

* . * * . * . * * {{DEFAULTSORT:Fredenhagen, Klaus Living people 20th-century German physicists 21st-century German physicists Academic staff of the University of Hamburg 1947 births People from Celle University of Hamburg alumni