In December 1971 Professor McConnell tendered his resignation as Director of the School and he was succeeded by Professor O’Raifeartaigh in January 1972. In the mean time preparations were in train for the filling of the Senior Professorship held by Professor Synge, who was due to retire in March. Interviews were held and the name of Dr. John Trevor Lewis was recommended for appointment no later than 1 October 1972. He had in fact been a regular speaker at the Symposia since 1962.

Professor Synge was appointed Professor Emeritus. After his retirement he remained active for a long time and maintained very strong links with the Institute, coming in regularly for discussions, in particular with Professor Lewis, even up to very advanced age.

In December 1972 various amendments to the Act were considered. This was inspired by a move to have the Institute recognised as an institute of higher education and to come under the aegis of the HEA. The position of Research Associateships was also revised and it was decided that they would in future not be confined to former members of the School. On 2 July 1973 the Minister for Education visited the Institute.

From January 1975 Professor Lewis took over the Directorship, a position he would hold for 25 years. In October the position of Research Associate was specified more precisely. It was resolved that any research worker of a standing comparable to a former Scholar and whose interests are close to that of the School could be considered; that they would be kept informed of activities of the School and granted library access; that the Director may allocate them a desk if they wish to spend a considerable part of their research time in the School, and that their publications would only be listed if they arise from work carried out in the School. Moreover, they could be granted expenses by the Board in connection with research carried out in the School only.

Since 1973 the School had argued for the establishment of a new administrative post of Clerk in the School. In August 1978, the Director formulated precise job descriptions for the two posts of Clerk and Librarian Executive respectively. The proposal was accepted by the Department of Education and on 1 March 1979 Mary Farrelly was appointed Secretary of the School. Eva Wills became Librarian-Executive.

In 1980 the format of the Symposia was slightly altered; there would in future by two invited review lecturers, four 40-minute lectures and 8 short communications. In March Mrs. Farrelly was recommended by the Board to become permanent Clerk of the School. But in October Mrs. Margaret Matthews was appointed instead. On 19 June 1981 the European Molecular Liquids Group was formally established, Prof. McConnell agreeing to serve on the Committee. He was appointed Chairman in October 1982. Professor Lewis was elected on the executive committee of the International Association of Mathematical Physics.

In October 1983 the Schrödinger Symposium was held in collaboration with the Austrian Embassy. There was another Schrödinger Commemoration in Imperial College in 1987. In December 1984 Professor McConnell wrote a tribute to Professor Paul Dirac, who died that month, in the “Irish Press”. Professor Dirac had an enormous influence on the Institute in its early years.

In 1980 plans were made for a new development at 10 Burlington Road. This plan was left in abeyance for several years, but in the beginning of 1985 the cause of a new building was taken up again with particular emphasis on the benefits of housing all Schools on a single site. In December 1985 unsatisfactory progress was recorded, however.

In November 1986 the Board visited Roebuck house with the view to moving the Institute as a whole to this site. The Board reported to Council that it was satisfied with its current accommodation but that it recognised the advantages of housing the Institute on a single site. The need for safeguarding the independence of the Institute was stressed. OPW plans subsequently showed that it was feasible to house the entire Institute on this site. The future of Dunsink was also being considered. In December 1986 President Hillery visited the Institute. In a letter of thanks he praised the staff for their hospitality and expressed his pride in the Institute, hoping that it would endure and prosper. Professor McConnell made the case for changing the name of the School to “Erwin Schrödinger School of Theoretical Physics”. Legal advice indicated that this change was outside the remit of the Board, however. In April 1987 this proposal was considered again. In March 1987 Professor Synge’s 90th birthday was celebrated with a one-day seminar. Speakers were Prof. R. Bott (Harvard) and Prof. N. Balazs (Stony Brook).

At the end of 1987 a threat of abolition was hanging over the Institute. The Grant-in Aid for 1988 was reduced by 35%, but in negotiations with the Government a contribution of £500,000 was granted to the School of Celtic Studies from Lottery funds. An appropriate redistribution of funds over the Schools was agreed by Council. In March 1988 a deputation of the Institute had a meeting with the Department of Education to consider the possibility of moving to the Custom House Dock site which was being developed. This plan was also doomed to fail eventually.

At the end of the year the financial situation eased somewhat, and normal estimates were submitted to the Department for 1989. However, the Assistant Professorship and the Senior Professorship vacated by Rev. Prof. McConnell upon his retirement in December 1987 were embargoed.

In November a permanent loan agreement was made with regard to the De Valera collection of scientific books. This collection is still in the School of Theoretical Physics and is now housed in a special “De Valera Room” which is also used as discussion room.

In January 1989 the President unveiled a Schrödinger plaque at his former residence in Clontarf under the aegis of the Irish-Austrian society. Subsequently, a pamphlet on Schrödinger by Emeritus Prof. McConnell was launched.

The Secretary of State visited the Institute in November and was apparently satisfied with the presentations by the Directors. But he intimated that continued justification was still required in order to secure funding. In December 1989 preparations for a Golden Jubilee Celebration were well under way and a publication was planned to honour the occasion. It was decided that each School should contribute an article in Irish. The 50-Year Report would unfortunately not appear until April1995 due to a lack of administrative staff. Miss Wills retired in 1990 as Librarian Executive. She was replaced by Mrs. Ann Goldsmith on a temporary basis but in December 1990 the Department refused sanction for the filling of the permanent post of Librarian Executive. Ann Goldsmith was retained as temporary Librarian owing to a generous offer from Cosmic Physics to deduct £10,000 from their Pay allocation for this purpose. Also in following years she was employed on a contract basis. It would take until April 1995 before she could be appointed to a permanent position as Librarian-Executive. In September 1996 she entered into a job-sharing arrangement with a Systems Administrator.

In April 1990 a case was prepared for the filling of the third Senior Professorship. A scheme was proposed to the Minister including a third Senior Professor, a Professor and an Assistant Professor.

During 1990 the Director (Prof. Lewis) and his group became involved in a collaboration with engineers from DCU concerning a Programme for Advanced Technology. This was a spin-off from their work on large deviation theory and concerned the efficient routing of information over communication lines.

An EOLAS grant was obtained for the collaboration with Dr. Buffet (DCU) on queuing networks. Contact was also made with a group in Cambridge.

In 1992 the Chairman of the Governing Board, Prof. A. J. McConnell resigned after more than 50 years of duty, 22 years as Chairman. The Board was to remain without Chairman until 1996, when Professor Cathleen Morawetz was appointed as new Chairman. Simultaneously the constitution of the Board was altered and several new members were appointed to the Board by the Minister. At the end of 1992, a substantial case was prepared for the appointment of a third Senior Professor to be presented to the Department. A meeting with a senior official in the Department was inconclusive, however, and it was then decided to rely on Article 12(2) of the Establishment Order rather than seek sanction. It was agreed that when the new Chairman was appointed a meeting with the Minister would be sought to discuss the School’s difficulties. It was stressed that no attempt would be made at any stage to specify a particular field. A review committee would be convened consisting of the Chairman of the Board with three external experts to make the case for the appointment of a Senior Professor.

The queuing network research was making considerable progress and meetings with industry were being set up to establish research collaboration and funding. It was hoped that this would also be helpful in convincing the Government to fill the Senior Professorship. In March 1993, Mentec Computer Systems agreed to support the School in an application to EOLAS under the Industrial Cooperation Scheme and to contribute £57,000. In April 1993 the project application was approved, the total sum involved being £105,000. The Dublin Applied Probability Group was formed and work commenced. In December 1994 considerable progress had been made but then Mentec decided to withdraw from the project. A new industrial partner was sought and members of the group visited and gave presentations at various telecommunications companies. This resulted in contact being established with a Swedish company, Telia Research and a joint research proposal with Cambridge University Computer Lab. and Telia Research was submitted for funding by the European ESPRIT programme. Funding for this programme with the name “Measure” was approved early 1995.

In 1996 Hewlett Packard expressed an interest to join the Measure project. They were willing to cover half the cost of an Assistant Professor. This year was the centenary year of Synge’s birthday and it was decided to erect a plaque in his honour on the building at 64 Merrion Square. Permission was obtained from the owners and the unveiling took place on 23 March 1997.

The Measure project was yielding significant results and a shared patent application was prepared. This led to a discussion about royalties and a single policy on IPR and Royalties for the two physics schools was prepared. The Board agreed that intellectual property rights could be transferred to a campus company set up in Cambridge in exchange for share options. But in February 1998, the Council withdrew from this agreement on the grounds that it was unclear if DIAS could hold equity. It was then proposed to consider the possibility of setting up a company in Dublin.

Following the success of this project a submission was made to the Department for further posts: 4 Assistant Professors and 2 Professors. The cost to the Exchequer would be small as some of the cost would come from contract income.

In March 1997 the advertisement for a Senior Professor in the School was approved by the Board. In July a shortlist was drawn up and a selection panel appointed. In February 1998 the Board agreed on the name of Dr. T. C. Dorlas to be forwarded to the Government for appointment to Senior Professor. The Board also recommended that Dr. D. O’Connor be appointed Professor and that sanction for this appointment should be sought a.s.a.p.

Professor Dorlas took up his position as Senior Professor in January 2000. In April 2000, Professor Lewis founded a company, named “Corvil” together with his two Assistant Professors Fergal Toomey and Raymond Russell to exploit the intellectual property developed with the European ESPRIT project called MEASURE. Several of his students, as well as the Systems Administrator Ian Dowse joined him in this endeavour.

Sadly, on 18 November 2000, Professor O’ Raifeartaigh died after a short illness. Just before that, in August, he had been awarded the prestigious Wigner Medal for his “pioneering contributions to particle physics”. A memorial conference in his honour was held in the Institute in June 2001. In December 2000 Dr. O’Connor’s name was submitted to the President for appointment as Senior Professor and a year later, in November 2001 his warrant was signed by the President. In January 2001 Professor Lewis was awarded one of the first SFI Fellowships to set up a new research group on Communication Technology, the Communications Network Research Institute, on the grounds of the Dublin Institute of Technology for a period of 5 years. There upon he resigned as Director and took leave of absense from the Institute. Professor Dorlas became Director of the School from 1 August 2001.

The sad loss of Professor O’Raifeartaigh and the departure of Professor Lewis effectively meant the end of an era for the School of Theoretical Physics, and the beginning of a new era. In the year 2000 the constitution of the Board had changed and Sir Michael Atiyah had taken over from Prof. Morawetz as Chairman. It was immediately resolved to advertise for an additional Senior Professor with the intention to have one in place by October 2002.

The year 2002 was in many ways a very eventful year for the Institute and the School of Theoretical Physics in particular. Already since 1998 a subcommittee of Council had been working on a Strategy Statement for the Institute. In 2001 a new Finance Officer was appointed, Mr. Cecil Keaveney. In the absence of a Registrar, he took up the task of completing the Strategy Document. The “Strategy Statement 2002-2006” appeared, and was officially presented to the Department, in May 2002. It contained plans for expansion of the Institute, a move to a new building which could house the whole Institute, and the establishment of a new category of temporary academic position to be called “Schrödinger Fellow” in the Physics Schools, and “Bergin Fellow” in the School of Celtic Studies. Even though only the last of these proposals has so far been fully realised, this document fostered enhanced cooperation between the Schools, under the leadership of the Chairman of Council, Professor Donnelly. In November 2002, Mr. Keaveney was appointed as the new Registrar.

Meanwhile, at the end of 2001, preparations had been under way for the appointment of a third Senior Professor. Fortunately, the Governing Board had a very eminent Chairman in Sir Michael Atiyah, who was able to enquire about suitable candidates. In January 2002 interviews were held and the interview committee, comprising Sir Michael Atiyah, Professor Gerard ‘t Hooft (Utrecht), Professor Joe Pule (UCD) and Profs. Dorlas and O’Connor unanimously agreed to propose the name of Professor Werner Nahm to the Government for appointment. This time the Government did not take very long to approve the appointment and Professor Nahm took up his position on 1 November 2002.

On 15 April 2002 Professor Lewis retired as Senior Professor and was appointed Emeritus Professor. He was still extremely active, being heavily involved with the new company Corvil and leading the research group CNRI at the same time. His retirement was marked by a small dinner in November 2002. Unfortunately, in October 2003 he fell ill and in January 2004 news came that he had passed away. This came as a tremendous shock to all his friends, especially since he had still been so active in recent years. It was immediately decided to hold a conference in his honour. It was organised by Profs. Dorlas and Goldsmith (DIT) and Dr. Ken Duffy (CNRI) and took place in the Dublin Institute of Technology in June 2005. Many of his friends paid tribute to his warm friendship, his tremendous encouragement and his great scientific achievements. He was Director of the School for 25 years and shepherded it through some of its most difficult periods.

Part of the Strategy Statement was a proposal to have an in-depth review carried out of the research of the three Schools by international panels of experts in the respective areas. It took place in November 2004 and the Review Panel of the School of Theoretical Physics, headed by Professor Arthur Jaffe (Harvard) commented that “The School of Theoretical Physics is a jewel within Ireland. Although it is a relatively small institution, the School plays an important role in focusing on science in Ireland and linking it with leading science in the rest of the world.” It also recommended the strengthening of the School with the appointment of at least two, preferably 3 new Senior Professors, and it endorsed the plans for a move to a new building to house all Schools as expressed in the Strategy Statement. At the time concrete plans were on the drawing board for a new building in Fenion Street, at the back of #5 Merrion Square, which houses the School of Cosmic Physics. This plan has since been stalled.

In May 2005, a new Board was appointed with Prof. Jaffe as Chairman. It was strengthened in 2006 with the appointment of four additional eminent members with the hope of realising the recommendations set out in the report of the review panel. A new Strategy Document is being prepared and is due to appear in May 2007.

The arrival of Prof. Lewis introduced a new line of research to the School. Although he had started his career with research into aspects of quantum mechanics, with the development of the Dalgarno-Lewis method while a Ph. D. student in Belfast, and the theory of generalised measurements and quantum Markov processes while in Oxford, his interest had shifted to Statistical Mechanics, partly under the influence of Mark Kac. The main lines of research in the School thus gradually became more focused to two areas: Statistical Mechanics and Quantum Field Theory. The following is a short synopsis of the most important work in these areas.

Upon his arrival, Prof. Lewis concentrated on four broad problems.

The first was the equilibrium statistical mechanics of lattice spin systems, esp. the Ising model. Together with Dr. Sisson he made an extensive study of a C*-algebraic formulation of the 2-dimensional Ising model. Initially they considered the quasi-free state corresponding to the high-temperature phase; then they considered the low-temperature phase, collaborating with Prof. Winnink (Groningen) and Dr. D. Evans. This eventually led to a calculation of the Atiyah-Singer index of the Clifford-algebra states and its relation to the phase transition. This work has formed the stimulus for subsequent work by Evans and others on C*-algebraic approaches to other classical spin models.

The second line of research concerned the phenomenon of Bose-Einstein condensation. First a detailed analysis was made of the quantum states associated with the free Bose gas together with Dr. Pule. This had in fact already been started in Oxford, and formed the basis of the latter’s thesis. This led to a complete understanding of the Bose-Einstein phase transition in this model, which had been predicted by Einstein in 1925. This research was taken up again in 1980 as a result of a visit to Groningen University, where Prof. Lewis met M. van den Berg, who was working on his thesis about models of a free Boson gas with an external field. After finishing his thesis, Dr. van den Berg came to DIAS as an Assistant Professor to continue the work on the boson gas. In the mean time, Prof. Lewis had learned about Large Deviation Theory from Prof. Doob during a conference. He immediately realised that this theory could be used to give a very simple derivation of the expression for the pressure of a boson gas with mean-field interaction, using a probabilistic description first introduced by Mark Kac. This stimulated a collaboration with Drs. Pule and Van den Berg, and later also Dr. Dorlas in applying the Large Deviation Principle to more complicated models of an interacting boson gas. In several models the existence of Bose-Einstein condensation could be proved and it became clear that this phenomenon is very sensitive to the details of the interaction. In a collaboration with Drs. Dorlas and Pule, another particular model of a boson gas with interaction was also analysed with this method: the one-dimensional boson gas with delta-interaction. Although there is no Bose-Einstein condensation in this model, it is of interest because it is exactly solvable using the so-called Bethe Ansatz. The rigorous analysis of this model may thus lead to a rigorous understanding of other models which can be solved with the Bethe Ansatz method.

The third line of research concerned the generalisation of Brownian motion to a sphere and subsequently more general manifolds. This work was done with Dr. Scaife and Prof. McConnell, who shifted his interest to statistical mechanics. It stimulated the latter into research into polarisation effects in dielectrics and into nuclear magnetic relaxation, about which he also wrote a book.

A fourth line of research was into quantum stochastic processes and in particular the quantum Langevin equation. This led to a 25-year long collaboration with Prof Ford (Ann Arbor) and Prof. O’Connell (Baton Rouge).

From 1990 onwards Prof. Lewis became involved in more applied research which was a spin-off from the experience acquired with Large Deviation Theory. He learnt that the rate function, a crucial object in Large Deviation Theory, also played a central role in the transmission of information. Hitherto it had been common practice to estimate this rate function using models of the transmission process, but Prof. Lewis realised that in thermodynamics the equivalent quantity, i.e. the entropy, would normally be measured directly and tabulated. He therefore suggested that this should also been done in communication, and he started a collaboration with Drs. Buffet and Duffield and with the Electronic Engineering department of DCU to study this problem further. This eventually led to the grant applications, the patents and the company Corvil described above.

In the 1970s Prof. O’Raifeartaigh worked on unified gauge theory and supersymmetry. Unified gauge theory was rapidly becoming the central paradigm of particle physics, and Prof. O’Raifeartaigh contributed to the understanding of spontaneous breaking of symmetry and constructed soliton solutions of gauge theory equations. He also worked on magnetic monopoles and the effective potential using loop expansions. In his work on supersymmetry he constructed one of the first models of spontaneous breakdown of supersymmetry without the use of gauge fields. In the 1980s, Prof. O’ Raifeartaigh wrote a book on “Group Structure of Gauge Theories”, and investigated the index theorem for noncompact spaces, generalising it to include scattering states. In 1988 he started work on 2-dimensional conformal invariance and the structure of Kac-Moody algebras together with Prof. W. McGlinn and Dr. Gorman. In 1989 he began what was to be his last great effort, a project that would continue for 10 years. He began a study of the reduction of the Wess-Zumino-Witten model of a topological quantum field theory to other quantum field theories, in particular the Toda field theories. Initially this work was done with Drs. Balog, Feher, Forgacs and Wipf, but later Drs. Ruelle and Tsutsui, and then Prof. McGlinn and Dr. Da Costa joined the effort. Initially they studied the principal SL(2) embeddings and associated reductions. Next it was extended to arbitrary SL(2) embeddings giving rise to new classes of conformally-invariant integrable systems. It was then shown that every conformally-invariant reduction of WZW theory requires an SL(2) embedding, but that the associated reductions are not entirely unique: apart from the canonical reductions there exist a few exceptional reductions, one of which being of particular interest. With Drs. Sachs and Wiesendanger, and subsequently also Drs. Pawlowski and Vinnakota functional integral methods were brought to bear on the quantisation of the WZW model. This led to the first explicit expressions for the n-point functions, which had previously only been given as solutions of the so-called Knizhnik-Zamolochikov equations. A related development was the derivation of a modified potential in Liouville theory which was shown to be the correct one for the quantised version of the theory.

During this time, various other problems were also studied, notably a generalisation of the spin-statistics theorem to arbitrary spaces of particles admitting pair creation and annihilation and a study of the Aharonov-Bohm effect. In 1995 Prof. O’ Raifeartaigh completed a book on “The Dawning of Gauge Theory”.

Apart from the regular Mathematical Symposiums at Easter and Christmas, there were more specific events. Some of these are described below:

In the summer of 1973 a Working Seminar was held on “Current Problems in Quantum Field Theory” and another in July 1974 on “Current Problems in Particle Physics”. Another Working Seminar was held in the summer of 1975 on “Current Problems in Probability and the Physical Sciences” and in October 1975 the School hosted the Conway Centenary Symposium. In 1979 a Working Seminar was organised on the topic “Current Problems in General Relativity”.

In the summer of 1982 a Summer School on Lasers in Solid State Physics was hosted by the School. The first European Conference of the Molecular Liquids Group was also held in the Institute, with the precise title: “Analytical and Computational Studies of Basic Problems in Molecular Liquids”.

In 1984 a Summer School on “Surfaces and Semiconductors” was held in the Institute. At the end of this Summer School there was a visit to the National Microelectronics Research Centre in Cork. A Symposium on “Modern Developments in Mechanics” was held in the Institute in April 1985, and another symposium on “Future Research in Molecular Liquids” in May 1985. In July 1986 a Workshop on “Brownian Motion and Stochastic Mechanics” was held.

There were a great number of distinguished visitors, notably Prof. J. A. Wheeler (Princeton), Prof. M. Kac (New York), Prof. Sir M. Atiyah (Oxford), Prof. F. Dyson (Princeton), Prof. D. Gross (CalTech), Prof. P. W. Higgs (Edinburgh), Prof. E. C. Zeeman (Warwick), Prof. Sir S. Edwards (Cambridge), Prof. H. Fröhlich (Liverpool), Prof. W. Thirring (Vienna), Prof. W. Nahm (Bonn), Prof. N. M. Hugenholtz (Groningen), Prof.H. Araki (Kyoto), Prof. M. Yor (Paris), Prof. J.-B. Zuber (Paris), Prof. J. Bell (Belfast and CERN), Prof. V. I. Arnold (Moscow), Prof. M. E. Fisher (Maryland), Prof. G. W. Mackey (Harvard).

With the appointment of Profs . Dorlas, O’Connor and Nahm, the main areas of research introduced by Profs. Lewis and O’ Raifeartaigh have been continued. Prof. Dorlas has worked on a lattice model of a boson gas called the Bose-Hubbard model, on models of a spin glass and on Anderson localisation in quasi-one-dimensional systems, and recently also on quantum information theory. Prof. O’ Connor has worked on noncommutative geometry and applications to quantum field theory, esp. as an alternative to lattice field theory, and on crossover phenomena and the renormalisation group. Prof. Nahm has worked on massive integrable field theories in the conformal limit and recently also on aspects of the quantum Hall effect in graphene.

The Mathematical Symposium is now held only once a year and is organised in collaboration with the Irish Mathematical Society. A number of international workshops have also been held on “Quantum Spaces” (Nov. 2004), “Causal Sets” (Dec. 2004), and “Mathematical Analysis of Quantum Systems” (Sept. 2001, 2002, 2003, 2004 and April 2007). There is a large number of visitors every year, often totalling in excess of 60. In May 2002 and 2006 the “Irish Quantum Field Theory Meeting” was held in the Institute. A John Lewis Lecture Series has been organised in collaboration with the Hamilton Mathematics Institute (Trinity College) since 2004. The first Distinguished John Lewis Lectureres were: Prof. J. Fröhlich (Zürich) in November 2005, and Prof. S. R. S. Varadhan (Courant Institute) in May 2006.

by Professor T. C. Dorlas