Presented by The Columbia University Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), and the Physical Sciences & Engineering Program
eBriefing 
A Fruitful Correspondence: The 9th Northeast String Cosmology Meeting
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Posted August 08, 2007
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Overview
On May 4, 2007, four eminent theorists addressed a wide variety of issues in string cosmology at a meeting held at the Academy in conjunction with the Institute for Strings, Cosmology and Astroparticle Physics (ISCAP) at Columbia University. Richard Bond reviewed the current status of cosmological observations, suggesting that the results continue to support the simple description of fluctuations in the background microwave radiation expected from traditional models of rapid cosmic inflation. He said this may change, however, once new probes of the microwave polarization pattern are available. Edward Witten explored traditional gravity in two spatial dimensions plus time, which he regards as the approach most likely to produce a model of gravity that is complex enough to allow black holes but still be potentially solvable. Nima Arkani-Hamed explained how understanding how long-lived metastable states driven by quantum fluctuations connect with and coexist with the true vacuum in which we live could illuminate some features of the landscape. He also showed that an effective field theory description breaks down not only at the very short Planck length scale, but also at more familiar scales when it implies a very large number of hidden degrees of freedom. Neil Turok of the University of Cambridge explored the idea that the Big Bang is not the beginning of time, but merely a particularly violent event in a continuously cycling universe.
Use the tabs above to find a meeting report and multimedia on this event.
Web Sites
AdS/CFT Correspondence
A String Theory Wiki entry collecting information on this concept.
The Cyclic Universe
For more on this topic, see this interview with Neil Turok at Edge.org, and this animation depicting Turok and Steinhardt's model.
European Space Agency Planck Science Team
This new satellite, due for launch this year, is being designed to explore the microwave background. Information about the scientific rationale for the project is available here (PDF, 9 MB).
Spider
The Caltech Observational Cosmology Group has been designing a balloon-based, bolometer-array experiment that will probe the cosmic microwave background.
Books
Green MB, Schwarz JH, Witten E. 1988. Superstring Theory, Volumes 1 & 2. Cambridge Monographs in Theoretical Physics. Cambridge University Press, New York.
Steinhardt PJ, Turok N. 2007. Endless Universe. Doubleday, New York.
Journal Articles
Maldacena JM. 1997. The large N limit of superconformal field theories and supergravity. Adv. Theor. Math. Phys. 2: 231-252. arXiv:hep-th/9711200v3.
Inflation Then and Now, and Cosmic Probes Now and Then
Bond JR, Kofman L, Prokushkin S & Vaudrevange PM. 2006. Roulette Inflation with Kähler moduli and their axions. arXiv:hep-th/0612197v2.
Kuo CL, Ade PAR, Bock JJ, et al. 2006. Improved measurements of the CMB power spectrum with ACBAR. arXiv:astro-ph/0611198v1.
2+1-Dimensional Gravity Revisited
Witten E. 2007. Three-dimensional gravity revisited. arXiv:0706.3359. (PDF, 640 KB) Full Text
Quantum Horizons and the Landscape
Arkani-Hamed N, Dubovsky S, Nicolis A, & Villadoro G. 2007. Quantum horizons of the Standard Model landscape. arXiv:hep-th/0703067v1.
Arkani-Hamed N, Dubovsky S, Nicolis A, Trincherini E & Villadoro G. 2007. A measure of de Sitter entropy and eternal inflation. arXiv:0704.1814v1 [hep-th].
Ekpyrotic Perturbations and a Holographic Big Bang
Lehners J-L, McFadden P, Turok N, Steinhardt PJ. 2007. Generating ekpyrotic curvature perturbations before the Big Bang. arXiv:hep-th/0702153v1.
Creminelli P, Senatore L. 2007. A smooth bouncing cosmology with scale invariant spectrum. arXiv:hep-th/0702165v1.
Buchbinder EI, Khoury J, Ovrut BA. 2007. New ekpyrotic cosmology. arXiv:hep-th/0702154v3.
Khoury J, Ovrut BA, Steinhardt PJ, Turok N. 2001. Density perturbations in the ekpyrotic scenario. Phys. Rev. D66 (2002) 046005. arXiv:hep-th/0109050v4.
Koyama K, Wands D. 2007. Ekpyrotic collapse with multiple fields. arXiv:hep-th/0703040v2.
Koyama K, Mizuno S, Wands D. 2007. Curvature perturbations from ekpyrotic collapse with multiple fields. arXiv:0704.1152v2 [hep-th].
Steinhardt PJ, Turok N. 2001. Cosmic evolution in a cyclic universe. Phys. Rev. D65 126003. arXiv:hep-th/0111098v2.
Tolley AJ, Wesley DH. 2007. Scale-invariance in expanding and contracting universes from two-field models. arXiv:hep-th/0703101v4.
Speakers
J. Richard Bond, PhD
Canadian Institute for Theoretical Astrophysics
e-mail | web site | publications
Richard Bond is University Professor at the University of Toronto, director of the Canadian Institute for Advanced Research Cosmology and Gravity Program, and past director of the Canadian Institute for Theoretical Astrophysics. His research interests include the physics of the very early universe, the origin and evolution of cosmic structure, cosmic radiation backgrounds, the dark matter and dark energy problems, and particle and gravitational theory. He is the recipient of numerous awards, including the Killam Prize in the Natural Sciences, the Herzberg Gold Medal, and fellowships from the Royal Society of London, the Institute of Physics, the American Physical Society, and the Royal Society of Canada.
Edward Witten, PhD
Institute for Advanced Study
e-mail | web site | publications
Edward Witten is a theoretical physicist and mathematician at the Institute for Advanced Study in Princeton, NJ. Credited as the founder of M theory and widely respected as one of the world's premier physicists, he has been the recipient of the Fields Medal, the MacArthur Prize, the Dirac Medal, and the National Medal of Science. He completed his PhD at Princeton University, where he was professor of physics from 1980–1987. He is the author of nearly two hundred scientific papers as well as a coauthor, with Michael Green and John Schwarz, of Superstring Theory, Volumes 1 and 2, published by Cambridge University Press.
Nima Arkani-Hamed, PhD
Harvard University
e-mail | web site | publications
Nima Arkani-Hamed is professor of physics at Harvard University. A member of Harvard's High Energy Theory Group, he is working to propose answers on topics like the hierarchy problem and the cosmological constant problem that might be tested with particle accelerators and cosmological observations. Arkani-Hamed completed his PhD at the University of California, Berkeley.
Neil Turok, PhD
Cambridge University
e-mail | web site | publications
Neil Turok is chair of mathematical physics at Cambridge University's Department of Applied Mathematics and Theoretical Physics. He completed his PhD at Imperial College, and subsequently held positions as associate scientist at Fermilab, reader at Imperial College, and professor at Princeton. He was awarded the James Clerk Maxwell Medal of the Institute of Physics in 1994 and he founded the African Institute of Mathematical Sciences in Cape Town, South Africa in 2003. He has proposed, with Paul Steinhardt, a cyclic model of the universe in which the Big Bang is explained as a collision between branes, and only the last in a potentially endless series of cycles of creation and expansion. The theory is described in their recent popular book Endless Universe: Beyond the Big Bang.
Don Monroe
Don Monroe is a science writer based in Murray Hill, New Jersey. After getting a PhD in physics from MIT, he spent more than fifteen years doing research in physics and electronics technology at Bell Labs. He writes on physics, technology, and biology.