Lochlainn O'Raifeartaigh (; 11 March 1933 – 18 November 2000) was an Irish

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

in the field of theoretical particle physics. He is best known for O'Raifeartaigh's no-go theorem, the O'Raifeartaigh Theorem, a result in unification theory, and the O'Raifeartaigh Model of supersymmetry breaking. O'Raifeartaigh was born in Clontarf,

Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...

in 1933, and attended St. Joseph's C.B.S. in Fairview and Castleknock College. Most of his scientific career was centred on that city, where he obtained his first degrees at University College Dublin (BA in 1953 and MSc in Mathematical Physics in 1956), and spent from 1968 until his death as Senior Professor at the

Dublin Institute for Advanced Studies The Dublin Institute for Advanced Studies (DIAS) () is a statutory independent research institute in Dublin, Ireland. It was established, under the Institute For Advanced Studies Act 1940, by the government of the then Taoiseach, Éamon de Vale ...

. He obtained his doctorate from the

University of Zurich The University of Zurich (UZH, ) is a public university, public research university in Zurich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 from the existing colleges of the ...

in 1960, under Walter Heitler. He also visited many institutions, notably Madras, IHES Bures, and the

Institute for Advanced Study The Institute for Advanced Study (IAS) is an independent center for theoretical research and intellectual inquiry located in Princeton, New Jersey. It has served as the academic home of internationally preeminent scholars, including Albert Ein ...

Princeton, New Jersey The Municipality of Princeton is a Borough (New Jersey), borough in Mercer County, New Jersey, United States. It was established on January 1, 2013, through the consolidation of the Borough of Princeton, New Jersey, Borough of Princeton and Pri ...

, but it was during an extended stay at

Syracuse University Syracuse University (informally 'Cuse or SU) is a Private university, private research university in Syracuse, New York, United States. It was established in 1870 with roots in the Methodist Episcopal Church but has been nonsectarian since 1920 ...

(1964-8) that he made the discovery that established his reputation. This result, which became known as O'Raifeartaigh's no-go theorem, showed that it was impossible to combine internal and relativistic symmetries other than in a trivial fashion, thus ending a widespread quest by the particle physics community to achieve this fusion. The O'Raifeartaigh theorem was later generalized to a result known as the Coleman–Mandula theorem. O'Raifeartaigh's prolific career in theoretical physics was manifested by many fundamental contributions to the application of symmetries in

particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

. In the 1970s he showed that the new supersymmetries could provide a mechanism (O'Raifeartaigh's mechanism) for circumventing his no-go theorem which had assumed only classical

Lie group In mathematics, a Lie group (pronounced ) is a group (mathematics), group that is also a differentiable manifold, such that group multiplication and taking inverses are both differentiable. A manifold is a space that locally resembles Eucli ...

symmetries. In the 1980s he applied non-Abelian gauge theory to the analysis of magnetic monopoles. His interests encompassed the spin-statistics theorem, Kac–Moody and W-algebras, and included early contributions to the theory of non-invariance (dynamical) groups, among much else. His long and productive career in the application of symmetry methods to theoretical physics was acknowledged by the award of the

Wigner Medal The International Colloquium on Group Theoretical Methods in Physics (ICGTMP) is an academic conference devoted to applications of group theory to physics. It was founded in 1972 by Henri Bacry and Aloysio Janner. It hosts a colloquium every tw ...

in August 2000. Lochlainn is the father of

Cormac O'Raifeartaigh Cormac O'Raifeartaigh (Cormac O'Rafferty) is an Irish physicist based at Waterford Institute of Technology in Ireland. A solid-state physicist by training, he is best known for several contributions to the study of the history and philosophy of ...

, an Irish physicist and of Úna Ní Raifeartaigh, an Irish lawyer who has been a Judge of the High Court and is currently serving as a Judge of the Court of Appeal.

Notes

External links

Article about O'Raifeartaigh on the DIAS website

Obituary
'' Physics Today'', November 2001 {{DEFAULTSORT:Oraifeartaigh, Lochlainn 1933 births 2000 deaths 20th-century Irish physicists Scientists from Dublin (city) Mathematical physicists Academics of the Dublin Institute for Advanced Studies