Bulletin of the American Physical Society
2013 Annual Meeting of the California-Nevada Section of the APS
Volume 58, Number 14
Friday–Saturday, November 1–2, 2013; Rohnert Park, California
Session D3: Gravitation |
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Chair: Kenneth Ganezer, CSU Domingo Hills Room: Darwin 37 |
Friday, November 1, 2013 4:12PM - 4:24PM |
D3.00001: Short-range Tests of Gravitational Physics Crystal Cardenas, A. Conrad Harter, C.D. Hoyle, Holly Leopardi, Dave Smith Due to the incompatibility of the Standard Model and General Relativity, tests of gravity remain at the forefront of experimental physics research. At Humboldt State University, undergraduates and faculty are developing an experiment that will test gravitational interactions below the 50-micron distance scale. The experiment will measure the twist of a torsion pendulum as an attractor mass is oscillated nearby in a parallel-plate configuration, providing a time varying torque on the pendulum. The size and distance dependence of the torque variation will provide means to determine deviations from accepted models of gravity on untested distance scales. To observe the twist of the pendulum inside the vacuum chamber, an optical system with nano-radian precision is required. This talk will provide a general overview of the experiment as well as address the measurement and characterization of environmental systematic effects which must be understood in order to achieve the required sensitivity. [Preview Abstract] |
Friday, November 1, 2013 4:24PM - 4:36PM |
D3.00002: Sensitivity Considerations for a Short-range Test of the Gravitational Inverse-square Law Dave Smith, Crystal Cardenas, A. Conrad Harter, C.D. Hoyle, Holly Leopardi The~gravitational~Inverse-Square Law (ISL) has been verified from infinity down to the 0.1 mm regime. Several theoretical scenarios predict~possible~violations of the ISL at short distances. At Humboldt State University, we are developing an experiment that will test gravitational interactions below 50 microns. The~experiment will be approximately null~by using a~stepped~torsion pendulum and a large attractor plate.~Thus, in the approximation that the attractor mass is~an infinite sheet of matter, the~Newtonian gravitational force does not depend on the separation distance between the pendulum and the attractor. The experiment will measure the torque applied to the pendulum as the attractor mass is oscillated nearby. The size and distance dependence of the torque variation will provide a means to determine any deviations from the ISL at untested scales. The mass distribution of the pendulum and attractor determine the sensitivity of the experiment. This talk will focus on the investigation of the ISL and the experimental sensitivity. Topics such as Gauss' Law of Gravitation,~the~infinite plane approximation, Yukawa~potential, and Newtonian vs. Yukawa torque will be discussed.~ Fabrication, modeling, and interaction of the attractor mass and pendulum will also be~covered. [Preview Abstract] |
Friday, November 1, 2013 4:36PM - 4:48PM |
D3.00003: Beyond Fefferman-Graham in higher-derivative theories of gravity Colin Cunliff The Fefferman-Graham expansion provides a natural tool for determining the asymptotic behavior of the metric and for addressing the question of appropriate boundary conditions for asymptotically (locally) anti-de Sitter (AlAdS) spacetimes. In general relativity, it has already proven to be an important tool in holographic renormalization and in the computation of correlation functions in the boundary CFT. However, for higher-derivative theories of gravity, the Fefferman-Graham expansion does not adequately account for the new gravitational degrees of freedom and their asymptotic behavior. This talk examines how to modify the Fefferman-Graham expansion to accommodate these higher-derivative theories. Some consequences of the modified FG expansion are presented for two particular theories: topologically massive gravity (TMG) and new massive gravity (NMG). [Preview Abstract] |
Friday, November 1, 2013 4:48PM - 5:00PM |
D3.00004: An Automated Photodetector Frequency Response Measurement System for LIGO Alexander Cole, Eric Gustafson LIGO will detect gravitational waves using laser interferometers that will be quantum noise limited over most of the apparatus's operating frequency range. To build an interferometric gravitational wave detector that works at the limits set by quantum mechanics, one must ensure that the detector can be controlled and read out optically. In the LIGO interferometers, several photodiodes are used to sense various degrees of freedom and provide feedback signals so that the cavities are in optical resonance. It is thus necessary to treat the photodiode and its readout electronics as systems whose performances, including frequency response, can change over time and with changing operating conditions. This project's purpose was to build an automatic frequency response measurement system for the interferometer's photodiodes. We use a modulated diode laser coupled through a fiber optic distribution system to illuminate the photodiodes, and then automatically and quickly measure the frequency response of each photoreceiver using a network analyzer and an RF switch to select the photodiodes one after another. The experiment was carried out at Caltech on the LIGO 40m prototype interferometer and designed with Advanced LIGO scalability in mind. [Preview Abstract] |
Friday, November 1, 2013 5:00PM - 5:12PM |
D3.00005: Rotating Black Holes in Shape Dynamics Gabriel Herczeg, Henrique Gomes Shape dynamics is a classical theory of gravity which agrees with GR in many important cases, but which possesses different gauge symmetries. Recently, it was shown that shape dynamics admits a Birkhoff theorem. The unique, spherically symmetric solution obtained is distinct from the corresponding solution for GR, the Schwarzschild spacetime. It is free of physical singularities, and while it possesses a horizon, it does not form a spacetime there. Here, we present a general procedure for (locally) mapping stationary, axisymmetric GR solutions onto their shape dynamic counterparts. This mapping furnishes the local form of the most general stationary, axisymmetric Shape Dynamics solution up to gauge transformations. We focus in particular on the rotating black hole solution for shape dynamics and show that many of the properties of the spherically symmetric solution are preserved in extending to the axisymmetric case: it is free of physical singularities, it does not form a spacetime at the horzion, and it possesses an inversion symmetry about the horizon. [Preview Abstract] |
Friday, November 1, 2013 5:12PM - 5:24PM |
D3.00006: A second high energy Hawking radiation predicted Jack Sarfatti Hawking's horizon surface area-entropy A black body radiation peaks at wavelength $\sim$A$^{1/2}$ $\sim$Unruh temperature T$^{-1}$. I predict a second higher Unruh temperature component with peak wavelength $\sim$ proper quantum thickness of the horizon $\sim$(LA$^{1/2}$)$^{1/2}$ with energy density $\sim$T$^{4}$ $\sim$hc/L$^2$A. The two Hawking surface and thickness radiations form a Carnot heat engine. L $=$ L$_{\mathrm{p}}$ corresponds to random black body gravity waves. L $\sim$ h/m$_{\mathrm{e}}$c for virtual electron-positron pairs stuck to the horizon corresponds to thermal photons. These apply both to observer independent black hole horizons as well as observer-dependent past and future cosmological horizons bounding the causal diamond. For gravity wave Hawking thickness radiation hc/L$_{\mathrm{p}}$$^2$A is the observed dark energy density if we use the future deSitter horizon entropy A. The Unruh effect suggests that the w $= \quad +$ 1/3 black body radiation for accelerating detectors corresponds to w $=$ -1 for the distant local inertial frame detectors. [Preview Abstract] |
Friday, November 1, 2013 5:24PM - 5:36PM |
D3.00007: Gravitational Lensing and Gravitational Waves Richard Kriske This author had introduced a completely original idea several years ago called ``The Theory of Horizons'' and is pleased to find that there is ample experimental evidence to move forward with this a legitimate theory of the Cosmos. The Horizon of a three curved dimensions with a perpendicular time dimension at each point in that space. It is easy to visualize that the perpendicular time dimension would take multiple angles to an observor, resulting in degrees of Red-shift and ability to ``see'' backward along the time axis, meaning the CMB changes. Since then B-mode polarisation has been detected,through a combination of data from the South-Pole Telescope and the ESA's Herschel Space Observatory. According to those sources the CMB encountered multiple galaxy clusters and had been deflected by this matter. The gravitational lensing imprinted a subtle distortion on the CMB, which has a small portion polarised, which carries additional directional information that could be used to observe Gravitational Waves. Although this is a somewhat different idea of detection than this Author had proposed this is the same theory, and this Author would like to move forward with the develop of a ``Theory of Horizons.'' There are some more exciting predictions that could be made with this theory. [Preview Abstract] |
Friday, November 1, 2013 5:36PM - 5:48PM |
D3.00008: Coulomb-Newton-Estakhr's Law of Gravitational Force and Eatakhr's Elementary Gravitational Mass Constant Ahmad Reza Estakhr I reformulate Newton's law of Gravitation base on Coulomb's law of the electrostatic interaction between electrically charged particles. first I consider Newton's Gravitational Constant $G$ as Coulomb's constant of Gravitation $k_g=\frac{1}{4\pi\epsilon_g}$. Where the $\epsilon_g$ is permittivity of Gravitational mass. So Gravitational Force is $F_G=k_g\frac{Mm}{r^2}$ then I consider Gravitational mass as a fraction of Estakhr's Elementary Gravitational mass Constant $M=n_1\mu_g$ and $m=n_2\mu_g$ where the $\mu_g$ denotes Estakhr's Elementary Gravitational mass Constant and $n$ denotes natural numbers. So Coulomb-Newton-Estakhr's Law of Gravitational Force is: $F_G=G\frac{n_1n_2\mu_g^2}{r^2}$ . then $\alpha_g=\frac{G\mu_g^2}{\hbar c}$ where the $\alpha_g$ is gravitational fine-structure constant and $\hbar$ is planck's constant and $c$ is speed of light, $m_p^2=\frac{\hbar c}{G}=\frac{\mu_g^2}{\alpha_g}$ then value of Estakhr's Elementary Gravitational mass Constant is $\mu_g=m_p\sqrt{\alpha_g}$ where $m_p$ denotes planck's mass, Estakhr's Elementary Gravitational mass Constant $\mu_g$ is a new fundamental physical constant and then by this way Covariant formulation of electromagnetism is applicable to Gravitation. [Preview Abstract] |
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