Editing Brian Greene (section)

==Academic career==
Greene joined the physics faculty of [[Cornell University]] in 1990, received tenure in 1993, and was appointed to a full professorship in 1995.<ref>{{Cite web |date=2020-04-08 |title=Brian Greene |url=https://www.ttbook.org/people/brian-greene |access-date=2025-01-22 |website=To The Best Of Our Knowledge}}</ref> The following year, he joined the faculty of [[Columbia University]] as a full professor.<ref name=":3">{{Cite web |date=2025-01-04 |title=Brian Greene {{!}} Biography, Books, & Facts {{!}} Britannica |url=https://www.britannica.com/biography/Brian-Greene |access-date=2025-01-22 |website=www.britannica.com |language=en}}</ref> At Columbia, Greene is director of the university’s center for theoretical physics and is leading a research program at the intersection of string theory, mathematical physics, and cosmology.<ref>{{Cite web |last=admin |title=Physics Research |url=https://www.briangreene.org/physics-research/ |access-date=2025-01-22 |website=Brian Greene |language=en-US}}</ref>

===Research===
Greene's area of research is [[string theory]], a candidate for a theory of [[quantum gravity]].  He is known for his contribution to the understanding of the different shapes the curled-up [[dimension]]s of string theory can take. The most important of these shapes are so-called [[Calabi–Yau]] manifolds; when the extra dimensions take on those particular forms, physics in three dimensions exhibits an abstract symmetry known as [[supersymmetry]].<ref>{{Cite journal |last=Candelas |first=P. |last2=Horowitz |first2=Gary T. |last3=Strominger |first3=Andrew |last4=Witten |first4=Edward |date=1985-01-01 |title=Vacuum configurations for superstrings |url=https://linkinghub.elsevier.com/retrieve/pii/0550321385906029 |journal=Nuclear Physics B |volume=258 |pages=46–74 |doi=10.1016/0550-3213(85)90602-9 |issn=0550-3213|url-access=subscription }}</ref>

Greene co-discovered a particular class of symmetry relating two different [[Calabi–Yau manifolds]], known as [[mirror symmetry (string theory)|mirror symmetry]]<ref>{{Cite journal |last=Greene |first=B. R. |last2=Plesser |first2=M. R. |date=1990-07-02 |title=Duality in Calabi-Yau moduli space |url=https://linkinghub.elsevier.com/retrieve/pii/055032139090622K |journal=Nuclear Physics B |volume=338 |issue=1 |pages=15–37 |doi=10.1016/0550-3213(90)90622-K |issn=0550-3213|url-access=subscription }}</ref> and is known for his research on the [[flop-transition]],<ref>{{Cite journal |last=Aspinwall |first=Paul S. |last2=Greene |first2=Brian R. |last3=Morrison |first3=David R. |date=1993-04-15 |title=Multiple mirror manifolds and topology change in string theory |url=https://linkinghub.elsevier.com/retrieve/pii/037026939391428P |journal=Physics Letters B |volume=303 |issue=3 |pages=249–259 |doi=10.1016/0370-2693(93)91428-P |issn=0370-2693|arxiv=hep-th/9301043 }}</ref><ref>{{Cite journal |last=Aspinwall |first=Paul S. |last2=Greene |first2=Brian R. |last3=Morrison |first3=David R. |date=1994-03-28 |title=Calabi-Yau moduli space, mirror manifolds and spacetime topology change in string theory |url=https://linkinghub.elsevier.com/retrieve/pii/0550321394903212 |journal=Nuclear Physics B |volume=416 |issue=2 |pages=414–480 |doi=10.1016/0550-3213(94)90321-2 |issn=0550-3213|arxiv=hep-th/9309097 }}</ref> a mild form of [[topology]] change, and also the conifold transition,<ref name=":0">{{Cite journal |last=Greene |first=Brian R. |last2=Morrison |first2=David R. |last3=Strominger |first3=Andrew |date=1995-09-25 |title=Black hole condensation and the unification of string vacua |url=https://linkinghub.elsevier.com/retrieve/pii/055032139500371X |journal=Nuclear Physics B |volume=451 |issue=1 |pages=109–120 |doi=10.1016/0550-3213(95)00371-X |issn=0550-3213|arxiv=hep-th/9504145 }}</ref> a more severe transformation of space, showing that topology in string theory can change smoothly.<ref>{{Cite book |title=Symétries quantiques =: Quantum symmetries: Les Houches, session LXIV, 1 Août - 8 Septembre 1995 |date=1998 |publisher=Elsevier Science |isbn=978-0-444-82867-5 |editor-last=Connes |editor-first=Alain |location=Amsterdam ; New York |pages=387–471 |editor-last2=Gawędzki |editor-first2=K. |editor-last3=Zinn-Justin |editor-first3=Jean}}</ref>

Greene has also studied [[string cosmology]], especially the imprints of [[Trans-Planckian problem|trans-Planckian]] physics on the [[cosmic microwave background]],<ref>{{Cite journal |last=Easther |first=Richard |last2=Greene |first2=Brian R. |last3=Kinney |first3=William H. |last4=Shiu |first4=Gary |date=2002-07-22 |title=Generic estimate of trans-Planckian modifications to the primordial power spectrum in inflation |url=https://journals.aps.org/prd/abstract/10.1103/PhysRevD.66.023518 |journal=Physical Review D |volume=66 |issue=2 |pages=023518 |doi=10.1103/PhysRevD.66.023518|arxiv=hep-th/0204129 }}</ref> and [[Membrane (M-theory)|brane]]-gas cosmologies that could explain why the space around us has three large [[dimension]]s.<ref>{{Cite journal |last=Greene |first=Brian |last2=Kabat |first2=Daniel |last3=Marnerides |first3=Stefanos |date=2010-08-25 |title=Dynamical decompactification and three large dimensions |url=https://journals.aps.org/prd/abstract/10.1103/PhysRevD.82.043528 |journal=Physical Review D |volume=82 |issue=4 |pages=043528 |doi=10.1103/PhysRevD.82.043528|arxiv=0908.0955 }}</ref> His work has expanded on the suggestion of a [[black hole electron]], namely that a [[black hole]] can continuously transform into a [[particle]] such as an [[electron]].<ref name=":0" />

Currently, Greene is studying non-[[Simply connected space|simply connected]] and non-[[Orientability|orientable]] [[Compactification (mathematics)|compactifications]] and has showed that in some of these contexts, signals can have an effective speed [[Faster-than-light|greater than that of light]], and even [[Time travel|travel back in time]].<ref>{{Cite journal |last=Greene |first=Brian |last2=Kabat |first2=Daniel |last3=Levin |first3=Janna |last4=Porrati |first4=Massimo |date=2023-01-27 |title=Back to the future: Causality on a moving braneworld |url=https://journals.aps.org/prd/abstract/10.1103/PhysRevD.107.025016 |journal=Physical Review D |volume=107 |issue=2 |pages=025016 |doi=10.1103/PhysRevD.107.025016|arxiv=2208.09014 }}</ref><ref>{{Cite journal |last=Greene |first=Brian |last2=Kabat |first2=Daniel |last3=Levin |first3=Janna |last4=Menon |first4=Arjun S. |date=2022-10-10 |title=Superluminal propagation on a moving braneworld |url=https://journals.aps.org/prd/abstract/10.1103/PhysRevD.106.085001 |journal=Physical Review D |volume=106 |issue=8 |pages=085001 |doi=10.1103/PhysRevD.106.085001|arxiv=2206.13590 }}</ref>