M. Ronen Plesser, Professor of Physics and Mathematics
My research is in String Theory, the most ambitious attempt yet at a comprehensive theory of the fundamental structure of the universe. In some (rather imprecise) sense, string theory replaces the particles that form the fundamental building blocks for conventional theories (the fields, or wave phenomena, we observe are obtained starting from particles when we apply the principles of quantum mechanics) with objects that are not pointlike but extended in one dimension – strings. At present, the theory is not precisely formulated, as we still seek the conceptual and technical tools needed. The structures we do have in hand suggest that, when formulated precisely, the theory will provide a consistent framework encompassing the two greatest achievements of twentieth century theoretical physics: Einstein’s general theory of relativity, which describes gravitational forces objects in terms of deformations of the geometry of spacetime; and quantum mechanics, a model of fundamental physics in which microscopic objects exhibit the properties of particles under some circumstances and those of waves under others. Both of these theories have been tested with extraordinary precision and yield predictions that agree with our observations of the physical universe. Relativistic effects are manifest at the largest scales in the universe, in the interactions of stars, galaxies, etc. The differences between a quantum mechanical description and a classical nineteenth century description of these objects are so small they can be neglected. Quantum effects dominate at the smallest scales – atoms and their constituents. In this realm, the effects of gravitation can be completely neglected. And yet, under extreme conditions of density, such as may obtain in the final instant of the evaporation of a black hole, both kinds of effects are important. A universal theory of physics thus requires a consistent quantum theory of gravity. Thus far, string theory is the most promising candidate for producing such a theory. Investigations of this theory have already yielded rich insights, and continue to produce more.
My own research centers on the crucial role played in the theory by geometric structures. There is an obvious role for geometry in a theory that incorporates gravitation, which as discussed above is tantamount to the geometry of spacetime. Related to this are several other, less obvious, geometric structures that play an important role in determining the physics of the theory. Indeed, advances in mathematics and in the physics of string theory have often been closely linked. An example of how the two fields have interacted in a surprising way is the ongoing story of mirror symmetry.  Contact Info:
Teaching (Fall 2020):
 HOUSECS 59.32, HOUSE COURSE (SP TOP)
Synopsis
 Physics 130, Tu 05:15 PM06:45 PM
 HOUSECS 59.33, HOUSE COURSE (SP TOP)
Synopsis
 Online ON, Tu 05:15 PM06:45 PM
 PHYSICS 134.01, INTRO TO ASTRONOMY
Synopsis
 Online ON, MW 03:30 PM04:45 PM
 Education:
Ph.D.  Harvard University  1991 
M.A.  Harvard University  1988 
BS  Tel Aviv University  1981 
 Specialties:

Theoretical particle physics and string theory
 Research Interests: String Theory and Quantum Field Theory
 Current Ph.D. Students
(Former Students)
 Postdocs Mentored
 Recent Publications
(More Publications)
 Jockers, H; Katz, S; Morrison, DR; Plesser, MR, SU(N) Transitions in MTheory on Calabi–Yau Fourfolds and Background Fluxes,
Communications in Mathematical Physics, vol. 351 no. 2
(April, 2017),
pp. 837871, Springer Nature [doi] [abs]
 Aspinwall, PS; Plesser, MR, General mirror pairs for gauged linear sigma models,
Journal of High Energy Physics, vol. 2015 no. 11
(November, 2015),
pp. 133, Springer Nature [doi] [abs]
 Morrison, DR; Ronen Plesser, M, Special Lagrangian torus fibrations of complete intersection CalabiYau manifolds: A geometric conjecture,
Nuclear Physics B, vol. 898
(September, 2015),
pp. 751770, Elsevier BV, ISSN 05503213 [doi] [abs]
 Bertolini, M; Plesser, MR, Worldsheet instantons and (0,2) linear models,
Journal of High Energy Physics, vol. 2015 no. 8
(August, 2015), Springer Nature [4541], [doi] [abs]
 Bertolini, M; Melnikov, I; Plesser, M, Massless spectrum for hybrid CFTs,
Proceedings of Symposia in Pure Mathematics
(December, 2014),
pp. 221230, American Mathematical Society [doi]
 Recent Grant Support
 Moduli Spaces of String Vacua with Four Supersymmetries, National Science Foundation, 2015/092019/08.
 A Regional Conference Series in Mathematical String Theory, National Science Foundation, PHY1316774, 2013/082019/08.
 Moduli Spaces of String Vacua with Four Supersymmetries, National Science Foundation, PHY 1521053, 2015/092018/08.
 Moduli Spaces of String Vacua with Four Supersymmetries, National Science Foundation, PHY 1521053, 2015/092018/08.
