18,464 research outputs found

    Discretizing Gravity in Warped Spacetime

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    We investigate the discretized version of the compact Randall-Sundrum model. By studying the mass eigenstates of the lattice theory, we demonstrate that for warped space, unlike for flat space, the strong coupling scale does not depend on the IR scale and lattice size. However, strong coupling does prevent us from taking the continuum limit of the lattice theory. Nonetheless, the lattice theory works in the manifestly holographic regime and successfully reproduces the most significant features of the warped theory. It is even in some respects better than the KK theory, which must be carefully regulated to obtain the correct physical results. Because it is easier to construct lattice theories than to find exact solutions to GR, we expect lattice gravity to be a useful tool for exploring field theory in curved space.Comment: 17 pages, 4 figures; references adde

    Gravity in the Randall-Sundrum Brane World

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    We discuss the weak gravitational field created by isolated matter sources in the Randall-Sundrum brane-world. In the case of two branes of opposite tension, linearized Brans-Dicke (BD) gravity is recovered on either wall, with different BD parameters. On the wall with positive tension the BD parameter is larger than 3000 provided that the separation between walls is larger than 4 times the AdS radius. For the wall of negative tension, the BD parameter is always negative but greater than -3/2. In either case, shadow matter from the other wall gravitates upon us. For equal Newtonian mass, light deflection from shadow matter is 25 % weaker than from ordinary matter. Hence, the effective mass of a clustered object containing shadow dark matter would be underestimated if naively measured through its lensing effect. For the case of a single wall of positive tension, Einstein gravity is recovered on the wall to leading order, and if the source is stationary the field stays localized near the wall. We calculate the leading Kaluza-Klein corrections to the linearized gravitational field of a non-relativistic spherical object and find that the metric is different from the Schwarzschild solution at large distances. We believe that our linearized solution corresponds to the field far from the horizon after gravitational collapse of matter on the brane.Comment: 8 pages, 1 figure. Replaced with revised version to be published in Phys. Rev. Lett. Some comments adde

    "Minsky Crisis"

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    Stability is destabilizing. These three words concisely capture the insight that underlies Hyman Minsky's analysis of the economy's transformation over the entire postwar period. The basic thesis is that the dynamic forces of a capitalist economy are explosive and must be contained by institutional ceilings and floors. However, to the extent that these constraints achieve some semblance of stability, they will change behavior in such a way that the ceiling will be breached in an unsustainable speculative boom. If the inevitable crash is "cushioned" by the institutional floors, the risky behavior that caused the boom will be rewarded. Another boom will build, and the crash that follows will again test the safety net. Over time, the crises become increasingly frequent and severe, until finally "it" (a great depression with a debt deflation) becomes possible. Policy must adapt as the economy is transformed. The problem with the stabilizing institutions that were put in place in the early postwar period is that they no longer served the economy well by the 1980s. Further, they had been purposely degraded and even in some cases dismantled, often in the erroneous belief that "free" markets are self-regulating. Hence, the economy evolved over the postwar period in a manner that made it much more fragile. Minsky continually formulated and advocated policy to deal with these new developments. Unfortunately, his warnings were largely ignored by the profession and by policymakers—until it was too late.Stability Is Destabilizing; Hyman Minsky; Money Manager Capitalism; Financial Instability Hypothesis; Global Financial Crisis; Self-Regulating Markets

    "Keynes's Approach To Money: An Assessment After 70 Years"

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    This paper first examines two approaches to money adopted by Keynes in the General Theory (GT). The first is the more familiar "supply and demand" equilibrium approach of Chapter 13 incorporated within conventional macroeconomics textbooks. Indeed, even Post Keynesians utilizing Keynes's "finance motive" or the "horizontal" money supply curve adopt similar methodology. The second approach of the GT is presented in Chapter 17, where Keynes drops "money supply and demand" in favor of a liquidity preference approach to asset prices that offers a more satisfactory treatment of money's role in constraining effective demand. In the penultimate section, I return to Keynes's earlier work in the Treatise on Money (TOM), as well as the early drafts of the GT, to obtain a better understanding of the nature of money. I conclude with policy implications.

    "The Continuing Legacy of John Maynard Keynes"

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    This working paper examines the legacy of Keynes’s General Theory of Employment, Interest, and Money (1936), on the occasion of the 70th anniversary of the publication of Keynes’s masterpiece and the 60th anniversary of his death. The paper incorporates some of the latest research by prominent followers of Keynes, presented at the 9th International Post Keynesian Conference in September 2006, and integrates this with other work that has come out of the Keynesian tradition since the 1940s. It is argued that Keynes’s contributions still provide important guidance for real-world policy formation.