Saturday, February 12, 2011

Brian Greene: The universe on a string

Brian Greene
Professor Mathematics & Physics
Columbia University

Theoretical Physics - String Theory & Quantum Gravity




Ph.D. 1987 Oxford University


My area of research is superstring theory, a theory that purports to give us a quantum theory of gravity as well as a unified theory of all forces and all matter. As such, superstring theory has the potential to realize Einstein's long sought dream of a single, all encompassing, theory of the universe. One of the strangest features of superstring theory is that it requires the universe to have more than three spatial dimensions. Much of my research has focused on the physical implications and mathematical properties of these extra dimensions --- studies that collectively go under the heading "quantum geometry".

Quantum geometry differs in substantial ways from the classical geometry underlying general relativity. For instance, topology change (the "tearing" of space) is a sensible feature of quantum geometry even though, from a classical perspective, it involves singularities. As another example, two different classical spacetime geometries can give rise to identical physical implications, again at odds with conclusions based on classical general relativity.

Superstring theory is most relevant under extreme physical conditions such as those that existed at the time of the big bang. Recently, we have formed a new institute at Columbia called ISCAP (Institute for Strings, Cosmology, and Astroparticle Physics) dedicated to understanding the interface of superstring theory and cosmology. One primary focus of ISCAP is the search for subtle signatures of string theory that may be imprinted in the precision cosmological data that will be collected through a variety of experiments over the next decade.


for a more complete listing of publications see SPIRES. Some selected publications are:
"Universal Correction to the Inflationary Vacuum", B. R. Greene, M. Parikh, and J.P. van der Schaar, {To Appear.}
 "An Effect of alpha' corrections on Racetrack Inflation", B. R. Greene and A. Weltman { JHEP 0603 (2006) 035.}
 "Extracting New Physics from the CMB", B. R. Greene, K. Schalm, G. Shiu, J.P. van der Schaar, {Proceedings XXIII Texas Symposium on Relativistic Astrophysics.}
 "Decoupling in an expanding Universe: Backreaction barely Constrains short distance effects on the CMB '', B. R. Greene, K. Schalm, G. Shiu, J.P. van der Schaar, { JCAP 0502 (2005) 001.}
 "String Windings in the Early Universe", R. Easther, B. R. Greene, M. Jackson, D. Kabat,
{JCAP 0502 (2005) 009.}
 "Brane Gases in the Early Universe: Thermodynaics and Cosmology", R. Easther, B. R. Greene, M. Jackson, D. Kabat, {JCAP 0401 (2004) 006.}
 "Brane Gas Cosmology in  M-Theory: Late Time Behavior", R. Easther, B. R. Greene, M. Jackson, D. Kabat, {Phys. Rev. D67 (2003) 123501.}
 "On the Hagedorn Behaviour of PP-wave Strings and N=4 SYM Theory at Finite R-Charge Density", B. R Greene, K. Schalm, G. Shiu, {Nucl.Phys. B652 (2003) 105.}
"A Generic Estimate of Trans-Planckian Modifications to the Primordial Power Spectrum in Inflation", R. Easther, B. Greene, W. Kinney, G. Shiu, Phys. Rev. D66 (2002) 023518.
"Inflation as a Probe of Short Distance Physics", R. Easther, B. Greene, W. Kinney, G. Shiu, Phys. Rev. D64 (2001) 103502.
"D-Brane Topology Changing Transitions", Brian R. Greene, Nucl. Phys. B525 (1998) 284-296.
"Orbifold Resolution by D-Branes", Michael R. Douglas, Brian R. Greene, David R. Morrison, Nucl.Phys. B506 (1997) 84-106.
"Black Hole Condensation and the Unification of String Vacua", Brian R. Greene, David R. Morrison, Andrew Strominger, Nucl.Phys. B451 (1995) 109-120.
"Calabi-Yau Moduli Space, Mirror Manifolds and Spacetime Topology Change in String Theory", P.S. Aspinwall, B.R. Greene, D.R. Morrison, Nucl.Phys. B416 (1994) 414-480
"Duality in Calabi-Yau Moduli Space", B.R.Greene and M.R.Plesser, Nucl. Phys. B338 (1990) 15.

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