Is string theory a theory of quantum gravity?

Some problems in finding a complete quantum theory incorporating gravity are discussed. One is that of giving a consistent unitary description of high-energy scattering. Another is that of giving a consistent quantum description of cosmology, with appropriate observables. While string theory addresses some problems of quantum gravity, its ability to resolve these remains unclear. Answers may require new mechanisms and constructs, whether within string theory, or in another framework.Comment: Invited contribution for "Forty Years of String Theory: Reflecting on the Foundations," a special issue of Found. Phys., ed. by G 't Hooft, E. Verlinde, D. Dieks, S. de Haro. 32 pages, 5 figs., harvmac. v2: final version to appear in journal (small revisions

Gauge/String-Gravity Duality and Froissart Bound

The gauge/string-gravity duality correspondence opened renewed hope and possibility to address some of the fundamental and non-perturbative QCD problems in particle physics, such as hadron spectrum and Regge behavior of the scattering amplitude at high energies. One of the most fundamental and long-standing problem is the high energy behavior of total cross-sections. According to a series of exhaustive tests by the COMPETE group, (1). total cross-sections have a universal Heisenberg behavior in energy corresponding to the maximal energy behavior allowed by the Froissart bound, i.e., $A + B ln^2 (s/s_0)$ with $B \sim 0.32 mb$ and $s_0 \sim 34.41 GeV^2$ for all reactions, and (2). the factorization relation among $\sigma_{pp, even}, \sigma_{\gamma p}, and \sigma_{\gamma \gamma}$ is well satisfied by experiments. I discuss the recent interesting application of the gauge/string-gravity duality of $AdS/CFT$ correspondence with a deformed background metric so as to break the conformal symmetry that can lead to the Heisenberg behavior of rising total cross-sections, and present some preliminary results on the high energy QCD from Planckian scattering in $AdS$ and black-hole production.Comment: 10 pages, Presented to the Coral Gables Conference 2003, Launching of BelleE\'poque in High Energy Physics and Cosmology, 17 - 21 December 2003, Fort Lauderdale, Florid

Nonlocality vs. complementarity: a conservative approach to the information problem

A proposal for resolution of the information paradox is that "nice slice" states, which have been viewed as providing a sharp argument for information loss, do not in fact do so as they do not give a fully accurate description of the quantum state of a black hole. This however leaves an information *problem*, which is to provide a consistent description of how information escapes when a black hole evaporates. While a rather extreme form of nonlocality has been advocated in the form of complementarity, this paper argues that is not necessary, and more modest nonlocality could solve the information problem. One possible distinguishing characteristic of scenarios is the information retention time. The question of whether such nonlocality implies acausality, and particularly inconsistency, is briefly addressed. The need for such nonlocality, and its apparent tension with our empirical observations of local quantum field theory, may be a critical missing piece in understanding the principles of quantum gravity.Comment: 11 pages of text and figures, + references. v2 minor text. v3 small revisions to match final journal versio

Precursors, black holes, and a locality bound

We revisit the problem of precursors in the AdS/CFT correspondence. Identification of the precursors is expected to improve our understanding of the tension between holography and bulk locality and of the resolution of the black hole information paradox. Previous arguments that the precursors are large, undecorated Wilson loops are found to be flawed. We argue that the role of precursors should become evident when one saturates a certain locality bound. The spacetime uncertainty principle is a direct consequence of this bound.Comment: 26 pages, 8 figs; reference added, minor clarification in sec. 2; incorrect draft mistakenly used in version

System development of the Screwworm Eradication Data System (SEDS) algorithm

The use of remotely sensed data is reported in the eradication of the screwworm and in the study of the role of the weather in the activity and development of the screwworm fly. As a result, the Screwworm Eradication Data System (SEDS) algorithm was developed

High energy QCD scattering, the shape of gravity on an IR brane, and the Froissart bound

High-energy scattering in non-conformal gauge theories is investigated using the AdS/CFT dual string/gravity theory. It is argued that strong-gravity processes, such as black hole formation, play an important role in the dual dynamics. Further information about this dynamics is found by performing a linearized analysis of gravity for a mass near an infrared brane; this gives the far field approximation to black hole or other strong-gravity effects, and in particular allows us to estimate their shape. From this shape, one can infer a total scattering cross-section that grows with center of mass energy as ln^2 E, saturating the Froissart bound.Comment: 27 pages, 1 fig, harvmac. v2: references added, typos corrected v3: typo correcte

Entropy in Black Hole Pair Production

Pair production of Reissner-Nordstrom black holes in a magnetic field can be described by a euclidean instanton. It is shown that the instanton amplitude contains an explicit factor of $e^{A/4}$, where $A$ is the area of the event horizon. This is consistent with the hypothesis that $e^{A/4}$ measures the number of black hole states.Comment: 24 pages (harvmac l mode

Cosmological diagrammatic rules

A simple set of diagrammatic rules is formulated for perturbative evaluation of ``in-in" correlators, as is needed in cosmology and other nonequilibrium problems. These rules are both intuitive, and efficient for calculational purposes.Comment: 7 pages, 3 figure

Petrology, mineralogy, and geochemistry of the Goldlund Gold Deposit, Northwestern Ontario

The Goldlund Mine is located in the Wabigoon Sub province of the Canadian Shield. Although the mine has been open sporadically since the late 1930\u27s, little is known about the geochemistry and petrography of the deposit. The purpose of this study was to use petro graphic, geochemical, and physical data to document and better understand the host rock, alteration, and mineral ization of the deposit, and to develop a generalized model of formation. Results showed that the host rocks of the gold mineral ization are albitized tonalite dikes. Gold, in native form and in gold-silver tellurides, occurs in quartz veins and in adjacent zones of metasomatic alteration within the tonalite. Two texturally different phases of albitized tonalite exist. A light, fine- to medium-grained phase, which contains the majority of gold mineralization, is surrounded by a dark, fine-grained border phase. Distinct alteration zones are present around quartz veins which fill tension fractures in the tonalite dikes. In addition to zones of visible alteration near the veins, cryptic zones farther from the veins were recog nized. Five alteration types recognized include: carbon atization, albitization, pyritization, desilicification, and dehydration. Geochemical data shows that carbon dioxide, sodium, calcium, and manganese were added to the tonalite from the veins, while iron, water, magnesium, and potassium were added to the veins from the tonalite. Corresponding mineralogical data suggests the breakdown of chlorite, biotite, and albite/quartz intergrowths, with formation of secondary carbonate, albite, pyrite, and vein quartz. A three-stage paragenetic sequence was recognized: an early, high temperature stage, a middle, dominantly sulfide stage, and a late, low temperature gold and telluride stage. Native gold, petzite, calavarite, and altaite were deposited in the late, low temperature stage. AFM, Q-Ab-Or, K-Na-Ca, Rb-Sr, Ti-Zr, Nb-Zr, and Y-Zr diagrams permit development of petrogenetic models for the intrusive rock types. The albitized tonalite dikes appear to have formed from a different magma source than the granite of the Crossecho Stock, the quartz monzonite stock, and the quartz-feldspar porphyries. The albitized tonalite dikes were probably derived by partial melting of amphibo lite and are syn-volcanic in age. The quartz-feldspar porphyries and quartz monzonite stock appear to be differentiated fractions of the magma of the Crossecho Stock and were intruded into the supracrustal assemblage during active plutonism of the Kenoran Orogeny. The Crossecho Stock and other late intrusives appear to have acted as concentrating agents, supplying heat and volatiles which mobilized gold from the surrounding volcanic rocks with subsequent deposition in tension fractures of the albitized tonalite dikes