Holger Bech Nielsen

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Holger Bech Nielsen

Holger Bech Nielsen (born August 25, 1941 in Copenhagen ) is a Danish theoretical physicist and held the chair for high energy physics at the Niels Bohr Institute at the University of Copenhagen from 1990 to 2012 . Nielsen is known in Denmark for his public lectures and TV reports and for his original, sometimes speculative ideas on particle physics.

Life

Nielsen studied physics in Copenhagen from 1961 and received his doctorate in 1968 at the Niels Bohr Institute on "Some consequences of the self-consistency of the quark model". 1969 to 1971 he was a Fellow of the Nordita in Copenhagen and 1971/72 visiting scientist at CERN (again 1999/2000). From 1973 to 1985 he was a lecturer at the Niels Bohr Institute, after which he became a research professor there, and from 1990 a full professor of high energy physics.

Various theoretical concepts are named after him. With Poul Olesen he introduced the Nielsen-Olesen vertex and Nielsen-Olesen vortex as part of early string theory in 1973 . and with Koba 1974 Koba-Nielsen variable and KNO-Scaling (Koba-Nielsen-Olesen-Scaling) The Nielsen-Ninomiya theorem explains why it is so difficult to represent (chiral) fermions on the grid. Either you have fermion doublings or broken chiral symmetry (i.e. no fermions with a small mass close to zero, such as neutrinos). Froggatt and Nielsen spontaneously discuss broken family symmetry to explain the mass hierarchy in the three Fermion families (Froggatt-Nielsen mechanism). The FNNS mechanism (Foerster-Nielsen-Ninomiya-Shenker mechanism) describes the creation of exact calibration symmetry on large scales from only approximate symmetry at the local level. For a long time, Nielsen has been pursuing a program to explain fundamental laws of nature based on random dynamics at the local level.

Ken Jonson named a concept by Nielsen et al. a. in the chiral bag model the “Cheshire Cat Principle” (CCP), after the disappearance of the smile with the Cheshire cat itself in Lewis Carroll's “ Alice in Wonderland ”. A fundamental theory with fermions "disappears" in the low-energy QCD in an effective meson theory. One theory is used to describe the nucleon in the bag (quarks, gluons), the other outside. At the edge of the bag, parameters of both theories are adjusted. The CCP says the physics of the model is independent of the exact value of the radius.

He is a member of the Danish Academy of Sciences and the Norwegian Academy of Sciences . In 2001 he received the German Humboldt Research Award .

literature

  • Colin Froggatt, Holger Bech Nielsen (Editor): Origin of Symmetries . World Scientific, Singapore 1991.
  • Henrik Georg Bohr, Holger Bech Nielsen: Wild and Not So Wild Dreams in Physics , Polyteknisk Boghandel Og Forlag 2014
  • Jens Kerte, Holger Bech Nielsen: Holgers univers. På rejse i tid og rum med en dansk super professor . Aschehoug, Copenhagen 2002.

Web links

Individual evidence

  1. ↑ Lars Henrik Aagaard: Smart physicist says goodbye (Danish) Berlingske online, September 1, 2012
  2. ^ Nielsen, Olsen, “A vortex line model for dual strings”, Nuclear Physics B 61, 1973, p. 45
  3. ↑ Koba, Nielsen, Olesen, Scaling of multiplicity distributions in high energy hadron scattering, Nuclear Physics B 40, 1972, p. 317
  4. ↑ Nielsen, Ninomiya “Absence of neutrinos from the lattice”, part 1, “Proof by homotopy theory”, Nuclear Physics B 185, 1981, p. 20 (erratum vol. 195, 1982, p. 541), part 2 “Intuitive topological proof ", Nuclear Physics B 193, 1981, p. 173
  5. ↑ Froggatt, Nielsen, Hierarchy of quark masses, Cabibbo angles and CP violation, Nuclear Physics B 147, 1979, pp. 277-298
  6. ^ Förster, Nielsen, Ninomiya, Dynamical stability of local gauge symmetry, Light from Chaos, Physics Letters B 94, 1980, p. 135
  7. ↑ Nielsen, A. Wirzba "Elementary Structure of Matter", Springer Proceedings in Physics Vol. 26, 1988, S. Nadkarni, Nielsen, I. ahed, Bosonization relations as bag boundary conditions, Nuclear Physics B 253, 1985, p. 308
personal data
SURNAME Nielsen, Holger Bech
BRIEF DESCRIPTION Danish physicist
DATE OF BIRTH August 25, 1941
PLACE OF BIRTH Copenhagen