nLab Michael Duff (changes)

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Michael Duff is professor of theoretical physics at Imperial College London. $\;\;$

He made foundational contributions to string theory and M-theory. $\;\;$

• personal webpage

• institute webpage

• Wikipedia entry

Autobiographical notes around encountering Chris Isham:

• Michael Duff, Chris Isham: mentor, colleague, friend (arXiv:2112.13722)

See also:

• Leron Borsten, Alessio Marrani, Christopher N. Pope, Kellogg Stelle, Introduction to the special issue dedicated to Michael J. Duff FRS on the occasion of his 70th birthday, Proceedings of the Royal Society A, 478 (2022) 2259 [[doi:10.1098/rspa.2022.0166](https://doi.org/10.1098/rspa.2022.0166)]

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Selected writings

On KK-compactification of 11-dimensional supergravity on a squashed 7-sphere with G₂-holonomy (M-theory on G₂-manifolds):

• Moustafa A. Awada, Mike Duff, Christopher Pope, $N=8$ Supergravity Breaks Down to $N=1$, Phys. Rev. Lett. 50 5 (1983) 294-297 [[doi:10.1103/PhysRevLett.50.294](https://doi.org/10.1103/PhysRevLett.50.294)]

• Mike Duff, Bengt Nilsson, Christopher Pope, Spontaneous Supersymmetry Breaking by the Squashed Seven-Sphere, Phys. Rev. Lett. 50, 2043 (1983) (doi:10.1103/PhysRevLett.50.2043, erratum)

On double dimensional reduction of the super-membrane (the M2-brane) to the Green-Schwarz superstring:

• Michael Duff, Paul Howe, T. Inami, Kellogg Stelle, Superstrings in $D=10$ from Supermembranes in $D=11$, Phys. Lett. B191 (1987) 70 and in Michael Duff (ed.) The World in Eleven Dimensions 205-206 (1987) (spire)

On the emergence of superconformal field theory in the perturbations of the super-membrane Green-Schwarz sigma model around a classical solution stretched along the asymptotic boundary of anti de Sitter spacetime:

• Eric Bergshoeff, Michael Duff, Christopher Pope, Ergin Sezgin: Supersymmetric Supermembrane Vacua and Singletons, Phys. Lett. B 199 (1987) 69-74 [doi:10.1016/0370-2693(87)91465-1, InSpire:250244]

• Mike Duff, C. Sutton, The Membrane at the End of the Universe, New Sci. 118 (1988) 67-71 (spire:268230)

predating the modern formulation of the AdS-CFT correspondence, amplified in

• Mike Duff, Anti-de Sitter space, branes, singletons, superconformal field theories and all that, Int. J. Mod. Phys. A14:815-844, 1999 (arXiv:hep-th/9808100)

On the corresponding brane scan of super-conformal branes:

• Miles P. Blencowe, Mike Duff, Supersingletons, Physics letters B, 203 3(1988) 229-236 (cds:184143, doi:10.1016/0370-2693(88)90544-8)

• Michael Duff, Near-horizon brane-scan revived, Nucl. Phys. B 810:193-209 2009 (arXiv:0804.3675)

• Michael Duff, The conformal brane-scan: an update (arXiv:2112.13784)

On quantization of the M2-brane Green-Schwarz sigma-model:

• Mike Duff, T. Inami, Christopher Pope, Ergin Sezgin, Kellogg Stelle, Semiclassical Quantization of the Supermembrane, Nucl.Phys. B297 (1988) 515-538 (spire:247064)

On Kaluza-Klein compactification

• Michael Duff, Kaluza-Klein Theory in Perspective, Proc. of the Symposium: The Oskar Klein Centenary, World Scientific, Singapore (1994) [[arXiv:hep-th/9410046](http://arxiv.org/abs/hep-th/9410046), doi:10.1142/2816]

and specifically in supergravity:

• Mike Duff, Bengt Nilsson, Christopher Pope, Kaluza-Klein supergravity, Physics Reports Volume 130, Issues 1–2, January 1986, Pages 1-142 (spire:229417, doi:10.1016/0370-1573(86)90163-8)

• Michael Duff, Bengt Nilsson, Christopher Pope: Kaluza-Klein Supergravity 2025, in: Half a Century of Supergravity – Part II: Structure and Properties of Sugra , [[arXiv:2502.07710](https://arxiv.org/abs/2502.07710)] Cambridge University Press (2026) 119–131 [[arXiv:2502.07710](https://arxiv.org/abs/2502.07710),doi:10.1017/9781009575874.018]

On black M2-brane-solutions to D=11 supergravity:

• Mike Duff, Kellogg Stelle, Multi-membrane solutions of $D = 11$ supergravity, Phys. Lett. B 253, 113 (1991) (spire:299386, doi:10.1016/0370-2693(91)91371-2)

On black branes and solitonic branes:

• Michael Duff, Ramzi R. Khuri, Jian Xin Lu, String and Fivebrane Solitons: Singular or Non-singular?, Nucl.Phys. B 377 (1992) 281-294 [[arXiv:hep-th/9112023](https://arxiv.org/abs/hep-th/9112023), doi:10.1016/0550-3213(92)90025-7]

• Michael Duff, Jian Xin Lu, Black and super $p$-branes in diverse dimensions, Nucl. Phys. B 416 (1994) 301-334 [[arXiv:hep-th/9306052](http://arxiv.org/abs/hep-th/9306052)]

• Mike Duff, Ramzi R. Khuri, Jian Xin Lu, String Solitons, Phys. Rept. 259 (1995) 213-326 [[arXiv:hep-th/9412184](https://arxiv.org/abs/hep-th/9412184), doi:10.1016/0370-1573(95)00002-X]

On M-theory:

• Michael Duff, M-Theory (the Theory Formerly Known as Strings), Int. J. Mod. Phys. A11 (1996) 5623-5642 (arXiv:hep-th/9608117)

• Michael Duff, The Theory Formerly Known as Strings, Scientific American 1998 (pdf, pdf)

• Michael Duff: A Layman’s Guide to M-theory, in: Trends in Mathematical Physics, AMS/IP Studies in Advanced Mathematics 13 (1999) 184-213 [[arXiv:hep-th/9805177](https://arxiv.org/abs/hep-th/9805177), cds:355721 doi:10.1090/amsip/013, ams:amsip/013]

• Michael Duff, The World in Eleven Dimensions (1999)

On the brane scan which classifies super $p$-brane sigma-models given by Green-Schwarz action functionals:

• Michael Duff, Supermembranes: the first fifteen weeks, Class. Quant. Grav. 5 (1988) 189 (doi:10.1088/0264-9381/5/1/023, spire:248034)

On string-string duality:

• Michael Duff, Ramzi Khuri, Four-Dimensional String/String Duality, Nucl.Phys. B411 (1994) 473-486 (arXiv:hep-th/9305142)

• Michael Duff, Ruben Minasian, Putting string/string duality to the test, Nucl.Phys. B436 (1995) 507-528 (arXiv:hep-th/9406198)

and specifically on the I8-term:

• Michael Duff, James Liu, Ruben Minasian, Eleven Dimensional Origin of String/String Duality: A One Loop Test, Nucl.Phys. B452 (1995) 261-282 (arXiv:hep-th/9506126)

On supergravity:

• Michael Duff, The status of local supersymmetry, in: From Quarks to Black Holes: Progress in understanding the logic of Nature, World Scientific (2005) 60-116 [[arXiv:hep-th/0403160](http://arxiv.org/abs/hep-th/0403160), doi:10.1142/9789812701794_0004]

On magic squares of magic supergravities and U-duality via the classical double copy:

• Leron Borsten, Michael Duff, Mia J. Hughes, Silvia Nagy, A magic square from Yang-Mills squared, Phys. Rev. Lett. 112 (2014) 131601 [[arXiv:1301.4176](http://arxiv.org/abs/1301.4176)]

• Alexandros Anastasiou, Leron Borsten, Michael Duff, Mia J. Hughes, Silvia Nagy, A magic pyramid of supergravities, JHEP (2014) 178 [[arXiv:1312.6523](http://arxiv.org/abs/1312.6523)]

On the early history of the notion of M-theory:

• Michael Duff: M-history without the M, Contemporary Physics 57 1 (2016) [[arXiv:1501.04098](http://arxiv.org/abs/1501.04098), doi:10.1080/00107514.2014.992964]

Interviews

• Interview by Graham Fermelo, The universe speaks in numbers – Interview 14 (web)

• Interview by Hisham Sati, Urs Schreiber, at M-Theory and Mathematics 2020:

  see: Duff interview at M-Theory-Mathematics 2020

Quotes

On the open problem of formulating M-theory:

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Duff 96, totality of Section 6:

The overriding problem in superunification in the coming years will be to take the Mystery out of M-theory, while keeping the Magic and the Membranes.

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Duff 98a, last paragraph (p. 6):

Despite all these successes, physicists are glimpsing only small corners of M-theory; the big picture is still lacking.

$[...]$

Indeed future historians may judge the late 20th century as a time when theorists were like children playing on the seashore, diverting themselves with the smoother pebbles or prettier shells of superstrings while the great ocean of M-theory lay undiscovered before them.

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Duff 98b, p. 6:

we are only just beginning to scratch the surface of the ultimate meaning of M-theory, and for the time being therefore, M stands for Magic and Mystery too.

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Duff 99, p.330:

future historians may judge the period 1984-95 as a time when theorists were like boys playing by the sea shore, and diverting themselves with the smoother pebbles or prettier shells of perturbative ten-dimensiorial superstrings while the great ocean of non-perturbative eleven-dimensional M-theory lay all undiscovered before them.

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Interview with Mike Duff by Graham Fermelo, The universe speaks in numbers – Interview 14 (web):

(17:04) The problem we face is that we have a patchwork understanding of M-theory, like a quilt. We understand this corner and that corner, but what’s lacking is the overarching big picture. So directly or indirectly, my research hopes to explain what M-theory really is. We don’t know what it is.

In a certain sense, and this is not a popular statement, I think it’s premature to be asking: “What are the empirical consequences”, because it’s not yet in a mature enough state, where we can sensibly make falsifiable prediction.

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Duff interview at M-Theory-Mathematics 2020:

(06:59) But the matrix model itself was not all of M-theory; it was a corner of M-theory, and it told us certain interesting things, but there were interesting things about M-theory that it didn’t tell us.

(07:13) I think we are still looking, in fact, for what M-theory really is.

(07:19) We have a patchwork picture. We understand various corners. But the overarching big picture of M-theory is still waiting to be discovered, in my view.

(08:12) M-theory in 1995 was very promising, and it’s taught us a lot about the fundamental interactions; but the final theory is still not with us.

(12:46) I wouldn’t like to predict what the ultimate picture of M-theory will be; I imagine it will be something quite different from what we can imagine now.

(16:36) That’s why I think M-theory is not yet in a mature enough stage for us to make falsifiable predictions.

(16:44) We don’t understand the theory sufficiently well yet to do so.

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