Quasilocal Conservation Laws: Why We Need Them

We argue that conservation laws based on the local matter-only stress-energy-momentum tensor (characterized by energy and momentum per unit volume) cannot adequately explain a wide variety of even very simple physical phenomena because they fail to properly account for gravitational effects. We construct a general quasi}local conservation law based on the Brown and York total (matter plus gravity) stress-energy-momentum tensor (characterized by energy and momentum per unit area), and argue that it does properly account for gravitational effects. As a simple example of the explanatory power of this quasilocal approach, consider that, when we accelerate toward a freely-floating massive object, the kinetic energy of that object increases (relative to our frame). But how, exactly, does the object acquire this increasing kinetic energy? Using the energy form of our quasilocal conservation law, we can see precisely the actual mechanism by which the kinetic energy increases: It is due to a bona fide gravitational energy flux that is exactly analogous to the electromagnetic Poynting flux, and involves the general relativistic effect of frame dragging caused by the object's motion relative to us.Comment: 20 pages, 1 figur

Dirac versus Reduced Quantization of the Poincar\'{e} Symmetry in Scalar Electrodynamics

The generators of the Poincar\'{e} symmetry of scalar electrodynamics are quantized in the functional Schr\"{o}dinger representation. We show that the factor ordering which corresponds to (minimal) Dirac quantization preserves the Poincar\'{e} algebra, but (minimal) reduced quantization does not. In the latter, there is a van Hove anomaly in the boost-boost commutator, which we evaluate explicitly to lowest order in a heat kernel expansion using zeta function regularization. We illuminate the crucial role played by the gauge orbit volume element in the analysis. Our results demonstrate that preservation of extra symmetries at the quantum level is sometimes a useful criterion to select between inequivalent, but nevertheless self-consistent, quantization schemes.Comment: 24 page

A New Approach to Black Hole Microstates

If one encodes the gravitational degrees of freedom in an orthonormal frame field there is a very natural first order action one can write down (which in four dimensions is known as the Goldberg action). In this essay we will show that this action contains a boundary action for certain microscopic degrees of freedom living at the horizon of a black hole, and argue that these degrees of freedom hold great promise for explaining the microstates responsible for black hole entropy, in any number of spacetime dimensions. This approach faces many interesting challenges, both technical and conceptual.Comment: 6 pages, 0 figures, LaTeX; submitted to Mod. Phys. Lett. A.; this essay received "honorable mention" from the Gravity Research Foundation, 199

Myths and Misconceptions in Fall Protection

Since 1973, when OSHA CFRs 1910 and 1926 began to influence the workplace, confusion about the interpretation of the standards has been a problem and fall protection issues are among them. This confusion is verified by the issuance of 351 (as of 11/25/05) Standard Interpretations issued by OSHA in response to formally submitted questions asking for clarification. Over the years, many workers and too many ES&H Professionals have become 'self-interpreters', reaching conclusions that do not conform to either the Standards or the published Interpretations. One conclusion that has been reached by the author is that many ES&H Professionals are either not aware of, or do not pay attention to the Standard Interpretations issued by OSHA, or the State OSHA interpretation mechanism, whoever has jurisdiction. If you fall in this category, you are doing your organization or clients a disservice and are not providing them with the best information available. Several myths and/or misconceptions have been promulgated to the point that they become accepted fact, until an incident occurs and OSHA becomes involved. For example, one very pervasive myth is that you are in compliance as long as you maintain a distance of 6 feet from the edge. No such carte blanche rule exists. In this presentation, this myth and several other common myths/misconceptions will be discussed. This presentation is focused only on Federal OSHA CFR1910 Subpart D--Walking-Working Surfaces, CFR1926 Subpart M--Fall Protection and the Fall Protection Standard Interpretation Letters. This presentation does not cover steel erection, aerial lifts and other fall protection issues. Your regulations will probably be different than those presented if you are operating under a State plan

Wideband radial power combiner/divider fed by a mode transducer

A radial power combiner/divider capable of a higher order (for example, N=24) of power combining/dividing and a 15% bandwidth (31 to 36 GHz). The radial power combiner/divider generally comprises an axially-oriented mode transducer coupled to a radial base. The mode transducer transduces circular TE01 waveguide into rectangular TE10 waveguide, and the unique radial base combines/divides a plurality of peripheral rectangular waveguide ports into a single circular TE01 waveguide end of the transducer. The radial base incorporates full-height waveguides that are stepped down to reduced-height waveguides to form a stepped-impedance configuration, thereby reducing the height of the waveguides inside the base and increasing the order N of combining/dividing. The reduced-height waveguides in the base converge radially to a matching post at the bottom center of the radial base which matches the reduced height rectangular waveguides into the circular waveguide that feeds the mode transducer

The horizon and its charges in the first order gravity

In this work the algebra of charges of diffeomorphisms at the horizon of generic black holes is analyzed within first order gravity. This algebra reproduces the algebra of diffeomorphisms at the horizon, (Diff(S^1)), without central extension

Properties of the symplectic structure of General Relativity for spatially bounded spacetime regions

We continue a previous analysis of the covariant Hamiltonian symplectic structure of General Relativity for spatially bounded regions of spacetime. To allow for near complete generality, the Hamiltonian is formulated using any fixed hypersurface, with a boundary given by a closed spacelike 2-surface. A main result is that we obtain Hamiltonians associated to Dirichlet and Neumann boundary conditions on the gravitational field coupled to matter sources, in particular a Klein-Gordon field, an electromagnetic field, and a set of Yang-Mills-Higgs fields. The Hamiltonians are given by a covariant form of the Arnowitt-Deser-Misner Hamiltonian modified by a surface integral term that depends on the particular boundary conditions. The general form of this surface integral involves an underlying ``energy-momentum'' vector in the spacetime tangent space at the spatial boundary 2-surface. We give examples of the resulting Dirichlet and Neumann vectors for topologically spherical 2-surfaces in Minkowski spacetime, spherically symmetric spacetimes, and stationary axisymmetric spacetimes. Moreover, we show the relation between these vectors and the ADM energy-momentum vector for a 2-surface taken in a limit to be spatial infinity in asymptotically flat spacetimes. We also discuss the geometrical properties of the Dirichlet and Neumann vectors and obtain several striking results relating these vectors to the mean curvature and normal curvature connection of the 2-surface. Most significantly, the part of the Dirichlet vector normal to the 2-surface depends only the spacetime metric at this surface and thereby defines a geometrical normal vector field on the 2-surface. Properties and examples of this normal vector are discussed.Comment: 46 pages; minor errata corrected in Eqs. (3.15), (3.24), (4.37) and in discussion of examples in sections IV B,

The visibility of environmental rights in the EU legal order: eurolegalism in action?

The current article responds to a key puzzle and a question. First, why, given the potential for ‘rights talk’ that has been seen in other countries and other policy areas, have environmental rights in the EU legal order been relatively invisible until recently? And second, with Daniel Kelemen’s influential work on Eurolegalism arguing that the EU has become much more reliant on US-style adversarial legalism, including a shift towards rights-based litigation, do EU environmental rights fit the picture Kelemen has painted, or are they an exception? The article explores the visibility of EU environmental rights at EU level and then seeks to explain the possible reasons for visibility/invisibility