About

Brian Greene is a professor of Physics and Mathematics at Columbia University and serves as the Director of Columbia’s Center for Theoretical Physics. He is recognized for a number of groundbreaking discoveries in mathematical physics and superstring theory. Professor Greene has authored several books, including The Elegant Universe, The Fabric of the Cosmos, The Hidden Reality, and Until the End of Time, which have collectively spent 67 weeks on The New York Times bestseller list and sold over two million copies worldwide. He is a frequent guest on late night television and was the host of two award-winning NOVA mini-series based on his books. Additionally, he wrote and performed in Light Falls, a live theatrical exploration of Einstein’s discoveries, broadcast nationally on PBS. Professor Greene co-founded the World Science Festival with Tracy Day and currently serves as Chairman of the Board.

Research topics

• Quantum mechanics
• Mathematical physics
• Physics
• Classical mechanics
• Theoretical physics
• Pure mathematics
• Mathematics

Selected publications

• Compactification Without Orientation, or a Topological Scenario for $CP$ Violation

  arXiv (Cornell University) · 2025-10-06

  preprintOpen access1st authorCorresponding

  In higher dimensional theories, we often assume that the extra dimensions form an orientable space, perhaps with singularities. However, many physical theories are well-defined on non-orientable spaces, and many spaces are not orientable, so it is reasonable to explore what happens if the assumption of orientability is relaxed. Here we consider the simplest example of free 6D theories compactified on a flat Klein bottle. We focus on a Dirac fermion in 6D, with boundary conditions that define ${\rm pin}^+$ and ${\rm pin}^-$ structures. Translation invariance is broken by the boundary conditions, which leads to sharp features localized near the parity walls (fixed points of the reflection used to construct the Klein bottle). For a scalar field, there is a position-dependent energy density, peaked near the parity walls. A Dirac fermion can lead to breaking of parity, charge conjugation and $CP$ in 3+1 dimensions. Order parameters for this breaking are provided by the vevs of certain fermion bilinears, again peaked near the parity walls. As one potential application, these results suggest mechanisms for $CP$ violation and baryogenesis, enabled by compactification on a Klein bottle.

  PublisherOA PDFDOI

• Klein Bottle Cosmology

  ArXiv.org · 2025-11-28

  preprintOpen access1st authorCorresponding

  We explore a higher-dimensional universe that is a product of Minkowski space and the non-orientable Klein Bottle. The topology explicitly breaks important symmetries, such as translational invariance and (5+1)-dimensional CP invariance. Somewhat surprisingly, the (3+1)-dimensional cp of the Minkowski space can also be broken by the Klein Bottle, both explicitly and in the presence of a brane. The topology enforces a background of fermion correlations that amounts to a condensate wall localized in the Klein Bottle. The wall acts as an order parameter for the broken symmetries. If a brane passes through the wall, brane fermions that couple to the condensate are produced as quantified by the Bogoliubov coefficients for a time-dependent mass. The scenario meets the conditions, including cp violation, to potentially generate the matter-antimatter asymmetry of the universe.

  PublisherOA PDFDOI

• Back to the future: Causality on a moving braneworld

  Physical review. D/Physical review. D. · 2023 · 10 citations

  1st authorCorresponding
  • Physics
  • Theoretical physics
  • Classical mechanics

  Brane observers executing appropriate motion through a partially compactified Lorentz invariant bulk spacetime, such as ${M}_{4}\ifmmode\times\else\texttimes\fi{}{S}^{1}$, can send signals along the brane that are instantaneous or even travel backward in time. Nevertheless, causality in the braneworld remains intact. We establish these results, which follow from superluminal signal propagation reported in Greene et al. [Superluminal propagation on a moving braneworld, Phys. Rev. D 106, 085001 (2022).], through classical analysis and then extend our reasoning by examining quantum mechanical microcausality. One implication is the capacity for real time communication across arbitrarily large distances.

  PublisherOA PDFDOI

• Superluminal propagation on a moving braneworld

  Physical review. D/Physical review. D. · 2022 · 10 citations

  1st authorCorresponding
  • Physics
  • Theoretical physics
  • Classical mechanics

  We consider a braneworld scenario in the simplest setting, ${M}_{4}\ifmmode\times\else\texttimes\fi{}{S}^{1}$, with a four-dimensional (4D) Minkowski metric induced on the brane, and establish the possibility of superluminal propagation. If the brane is at rest, the 4D Lorentz symmetry of the brane is exact, but if the brane is in motion, it is broken globally by the compactification. By measuring bulk fields, an observer on the brane sees a slice through a higher-dimensional field profile, which carries an imprint of the extra dimensions even when the brane is at rest. If the brane is in motion, we find that bulk fields can propagate outside the brane light cone by a parametrically large amount set by the brane velocity. We mention observational tests and possible applications to cosmology.

  PublisherOA PDFDOI

• Superluminal Propagation on a Moving Braneworld

  arXiv (Cornell University) · 2022

  1st authorCorresponding
  • Physics
  • Theoretical physics
  • Classical mechanics

  We consider a braneworld scenario in the simplest setting, $M_4 \times S^1$, with a 4D Minkowski metric induced on the brane, and establish the possibility of superluminal propagation. If the brane is at rest, the 4D Lorentz symmetry of the brane is exact, but if the brane is in motion, it is broken globally by the compactification. By measuring bulk fields, an observer on the brane sees a slice through a higher-dimensional field profile, which carries an imprint of the extra dimensions even when the brane is at rest. If the brane is in motion we find that bulk fields can propagate outside the brane lightcone by a parametrically large amount set by the brane velocity. We mention observational tests and possible applications to cosmology.

  PublisherOA PDFDOI

• Back to the Future: Causality on a Moving Braneworld

  arXiv (Cornell University) · 2022-08-18

  preprintOpen access1st authorCorresponding

  Brane observers executing appropriate motion through a partially compactified Lorentz invariant bulk spacetime, such as $M_4 \times S^1$, can send signals along the brane that are instantaneous or even travel backward in time. Nevertheless, causality in the braneworld remains intact. We establish these results, which follow from superluminal signal propagation reported in arXiv:2206.13590, through classical analysis and then extend our reasoning by examining quantum mechanical microcausality. One implication is the capacity for real time communication across arbitrarily large distances.

  PublisherOA PDFDOI

• Bibliographie

  Flammarion eBooks · 2021-02-24

  book-chapter1st authorCorresponding
  PublisherDOI

• LibGuides: Library Operations During COVID Restrictions: Home

  2020-03-17

  libguides1st authorCorresponding
  Publisher

• Weeding a shared e-book collection: Collaboration across a consortium

  College & Research Libraries News · 2018-10-04 · 3 citations

  articleOpen access

  Collection weeding is an important function of any library operation. At its simplest, the process of deciding what to remove, and implementing it, is controlled by a library or system serving a single mission and set of objectives. This becomes more complicated when the collection is shared by a group of libraries, such as those within a consortium, that have separate governing structures. The difficulty of such an undertaking is further compounded for collections of electronic resources with varying licensing terms and technical configurations. This paper describes just such a weeding project of an e-book collection shared by members of a large library consortium.

  PublisherOA PDFDOI

• LibGuides: MLA Style Guide, 8th Ed.: Media

  2017-03-02

  libguides1st authorCorresponding
  Publisher

Frequent coauthors

• David R. Morrison

  University of California, Santa Barbara

  28 shared

• Daniel Kabat

  22 shared

• Gary Shiu

  19 shared

• Shing‐Tung Yau

  Beijing Institute of Mathematical Sciences and Applications

  17 shared

• Jonathan King

  Bridge University

  16 shared

• Joseph Polchinski

  16 shared

• Pamela A. Thuman-Commike

  QED Labs

  16 shared

• Wah Chiu

  Stanford University

  14 shared