# Paul Townsend
**Paul Kingsley Townsend** (P.K. Townsend) is a theoretical physicist, currently Professor of Theoretical Physics at the Department of Applied Mathematics and Theoretical Physics (DAMTP) of the [University of Cambridge](https://www.edgepedia.org/university-of-cambridge).[1](https://www.damtp.cam.ac.uk/person/pkt10) His work spans general relativity, supersymmetry, string and M-theory, solitons and cosmology,[1](https://www.damtp.cam.ac.uk/person/pkt10) and he is known in particular for contributions to the early formulation of supergravity, for the theory of the solitons of supergravity known as supermembranes, and for the 2009 formulation of massive gravity in three spacetime dimensions.[1](https://www.damtp.cam.ac.uk/person/pkt10) • [2](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301)
| Key facts | |
|---|---|
| Position | DAMTP Professor of Theoretical Physics, University of Cambridge (DAMTP lecturer since 1984)[1](https://www.damtp.cam.ac.uk/person/pkt10) |
| Field | Theoretical high-energy physics: general relativity, supersymmetry, string/M-theory, solitons, cosmology[1](https://www.damtp.cam.ac.uk/person/pkt10) |
| Training | Undergraduate Cambridge; PhD Brandeis University, 1976, advisor Howard Joel Schnitzer[3](https://www.mathgenealogy.org/id.php?id=103859) • [4](https://inspirehep.net/authors/985767) |
| Signature work | "Massive Gravity in Three Dimensions", Physical Review Letters 102, 201301 (2009)[2](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301) |
| Honours | Fellow of the Royal Society (2000); William Hopkins Prize of the Cambridge Philosophical Society[1](https://www.damtp.cam.ac.uk/person/pkt10) • [5](https://www.admin.cam.ac.uk/reporter/1999-2000/weekly/5807/51.html) |
| Recent output | Papers on causal and self-dual electrodynamics (2024–2025) and preprints through January 2026[4](https://inspirehep.net/authors/985767) |
## Training and career
Townsend took his undergraduate degree at the University of Cambridge and completed his PhD at [Brandeis University](https://www.edgepedia.org/brandeis-university) in 1976, with a dissertation titled "The 1/n Expansion of Scalar Field Theories" supervised by Howard Joel Schnitzer.[3](https://www.mathgenealogy.org/id.php?id=103859) • [4](https://inspirehep.net/authors/985767) He then held postdoctoral positions at the [State University of New York](https://www.edgepedia.org/state-university-of-new-york) at Stony Brook, at CERN as a UK junior fellow, and at the École Normale Supérieure in Paris as a Joliot-Curie fellow.[1](https://www.damtp.cam.ac.uk/person/pkt10) In 1984 he was appointed a lecturer at Cambridge DAMTP, where he is currently Professor of Theoretical Physics.[1](https://www.damtp.cam.ac.uk/person/pkt10)
## Field and research program
Townsend's self-described research interests are general relativity, supersymmetry, string, and M-theory, solitons, cosmology, and topics in mathematical physics.[1](https://www.damtp.cam.ac.uk/person/pkt10) A Cambridge DAMTP conference held on 2–3 July 2012 to mark his 60th birthday summarized a career of nearly 40 years as including seminal contributions in supersymmetry, supergravity, dualities, and the properties of extended objects, or "branes".[6](https://www.damtp.cam.ac.uk/research/hep/branes-supergravity-and-m-theorya-conference-celebrate-60th-birthday-paul-k-townsend-0)
The prize citation records the arc of that work precisely. The Cambridge Philosophical Society, awarding him its William Hopkins Prize, credited his contributions to the original formulation of supergravity, his origination of many of the most significant ideas on the solitons of supergravity theories, known as supermembranes, and his development in 1994 of nonperturbative duality symmetries in string theory that led to a unified understanding of all superstring theories together with supergravity.[5](https://www.admin.cam.ac.uk/reporter/1999-2000/weekly/5807/51.html) The DAMTP conference page states the same result in its modern form: his discoveries revealed that the various string theories, previously thought to be defined in ten spacetime dimensions, are all different aspects of a single eleven-dimensional theory now called M-theory.[6](https://www.damtp.cam.ac.uk/research/hep/branes-supergravity-and-m-theorya-conference-celebrate-60th-birthday-paul-k-townsend-0)
## Representative work
**Massive Gravity in Three Dimensions** ([Physical Review Letters](https://www.edgepedia.org/physical-review-letters) 102, 201301, published 21 May 2009) is a 2009 paper by Townsend in gravitational physics.[2](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301) • [7](https://arxiv.org/abs/0901.1766) The paper shows that a particular higher-derivative extension of the Einstein-Hilbert action in three spacetime dimensions is equivalent, at the linearized level, to the unitary Pauli-Fierz action for a massive spin-2 field.[2](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301) A more general model in the paper, which includes topologically massive gravity as a special case, propagates the two spin-2 helicity states with different masses, and a cosmological extension admits an anti-de Sitter vacuum.[2](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301) The paper appeared as arXiv:0901.1766 in January 2009.[7](https://arxiv.org/abs/0901.1766) In Townsend's own later summary, the resulting theory, new massive gravity (NMG), is a generally covariant, ghost-free, non-linear extension of the three-dimensional Fierz-Pauli theory (baseline theory of a free massive spin-2 field): it propagates a parity doublet of massive gravitons, has no other local degrees of freedom, and is unitary, with the Einstein-Hilbert term entering with the wrong sign but propagating no modes.[8](http://www.physics.ntua.gr/cosmo13/Paros2013/Talks/Townsend.pdf)
## New Massive Gravity and the 3D gravity landscape
A 2009 review by the authors of the original paper places NMG in a wider program. The free three-dimensional Fierz-Pauli theory extends to interacting covariant theories in two ways: NMG, whose action involves curvature-squared terms, and three-dimensional bigravity, which involves non-linear couplings of the Fierz-Pauli field to three-dimensional Einstein-Hilbert gravity.[9](https://ar5iv.labs.arxiv.org/html/0912.2944) Adding a Lorentz Chern-Simons term to NMG yields "general massive gravity" (GMG), with two mass parameters, of which both NMG and topologically massive gravity are special cases.[9](https://ar5iv.labs.arxiv.org/html/0912.2944)
The comparison with four-dimensional massive gravity is a comparison of methods and scope. The four-dimensional ghost-free program, commonly called dRGT massive gravity, resummed in Physical Review Letters 106, 231101 in 2011, carries five gravitational degrees of freedom with helicity-2, helicity-1, and helicity-0 modes; a 2026 analysis proves that its two helicity-2 degrees propagate exactly on the metric lightcone at high frequency on any background.[10](https://arxiv.org/html/2604.22418) Three-dimensional massive gravity, by contrast, is built around a parity doublet of massive spin-2 modes.[8](http://www.physics.ntua.gr/cosmo13/Paros2013/Talks/Townsend.pdf) • [9](https://ar5iv.labs.arxiv.org/html/0912.2944)
## Recent work (2023–2026)
Townsend has continued publishing. His record through 2025 includes about 3 papers in 2024–2025 in the [Journal of High Energy Physics](https://www.edgepedia.org/journal-of-high-energy-physics) and [Physical Review D](https://www.edgepedia.org/physical-review-d) on causal and self-dual electrodynamics,[1](https://www.damtp.cam.ac.uk/person/pkt10) a March 2025 preprint titled "A brief history of supermembranes",[4](https://inspirehep.net/authors/985767) and a January 2026 preprint on black holes and causal nonlinear electrodynamics.[4](https://inspirehep.net/authors/985767) Earlier, his papers included "The Third Way to 3D Gravity" (International Journal of Modern Physics D, 2015), "The Galilean Superstring" (JHEP, 2017), and "Anti-de Sitter particles and manifest (super)isometries" (Physical Review Letters 118, 2017).[11](https://www.maths.cam.ac.uk/person/pkt10)
## References
1. [Professor Paul Kingsley Townsend | DAMTP, University of Cambridge](https://www.damtp.cam.ac.uk/person/pkt10)
2. [Massive Gravity in Three Dimensions | Physical Review Letters 102, 201301 (2009)](https://link.aps.org/doi/10.1103/PhysRevLett.102.201301)
3. [Paul Townsend | The Mathematics Genealogy Project](https://www.mathgenealogy.org/id.php?id=103859)
4. [Paul Kingsley Townsend | INSPIRE-HEP author record](https://inspirehep.net/authors/985767)
5. [Reporter 27/4/00: Philosophical Society (William Hopkins Prize), University of Cambridge](https://www.admin.cam.ac.uk/reporter/1999-2000/weekly/5807/51.html)
6. [Branes, Supergravity and M-Theory: a conference to celebrate the 60th birthday of Paul K Townsend | DAMTP](https://www.damtp.cam.ac.uk/research/hep/branes-supergravity-and-m-theorya-conference-celebrate-60th-birthday-paul-k-townsend-0)
7. [Massive Gravity in Three Dimensions | arXiv:0901.1766](https://arxiv.org/abs/0901.1766)
8. [New Massive Gravity (lecture slides, P.K. Townsend, Paros 2013)](http://www.physics.ntua.gr/cosmo13/Paros2013/Talks/Townsend.pdf)
9. [On massive gravitons in 2+1 dimensions (Bergshoeff, Hohm, Townsend review)](https://ar5iv.labs.arxiv.org/html/0912.2944)
10. [Graviton propagation in ghost-free massive gravity | arXiv](https://arxiv.org/html/2604.22418)
11. [Professor Paul Kingsley Townsend | Faculty of Mathematics, University of Cambridge](https://www.maths.cam.ac.uk/person/pkt10)
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Physicists and astronomers › Researchers in particle, nuclear, and high-energy theoretical physics › String theory and quantum gravity*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026 · Edited: Sep 25, 2026; Oct 11, 2026; Oct 25, 2026 · Last review: Sep 25, 2026*
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