Bulletin of the American Physical Society
2011 Annual Meeting of the California-Nevada Section of the APS
Volume 56, Number 14
Friday–Saturday, November 11–12, 2011; Menlo Park, California
Session F4: Gravitation |
Hide Abstracts |
Chair: Warren Rogers, Westmont College Room: Bldg 51 - Kavli 3rd Floor Conference Room |
Saturday, November 12, 2011 1:00PM - 1:12PM |
F4.00001: Novel Tests of Short-range Gravitational Physics at Humboldt State University Holly Leopardi, Brandon Baxley, C.D. Hoyle, Matthew Richards, David Shook Due to the incompatibility of the Standard Model and General Relativity (GR), tests of gravity remain at the forefront of experimental physics. There is yet to be a theory that unifies inconsistencies between GR and quantum mechanics; however, some scenarios of String Theory predict more than three spatial dimensions that could alter the gravitational inverse-square law at short distances. Some models also predict unobserved subatomic particles that may cause short-range violations of the Weak Equivalence Principle. 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 focus on the current status of the experiment, and the development of an optical system with the required sensitivity. [Preview Abstract] |
Saturday, November 12, 2011 1:12PM - 1:24PM |
F4.00002: Predicted Sensitivity for Tests of Short-range Gravity with a Novel Parallel-plate Torsion Pendulum Matthew Richards, Brandon Baxley, C.D. Hoyle, Holly Leopardi, David Shook The parallel-plate torsion pendulum apparatus at Humboldt State University is designed to test the Weak Equivalence Principle (WEP) and the gravitational inverse-square law (ISL) of General Relativity at unprecedented levels in the sub-millimeter regime. Some versions of String Theory predict additional dimensions that might affect the gravitational inverse-square law (ISL) at sub-millimeter levels. Some models also predict the existence of unobserved subatomic particles, which if exist, could cause a violation in the WEP at short distances. Short-range tests of gravity and the WEP are also instrumental in investigating possible proposed mechanisms that attempt to explain the accelerated expansion of the universe, generally attributed to Dark Energy. The weakness of the gravitational force makes measurement very difficult at small scales. Testing such a minimal force requires highly isolated experimental systems and precise measurement and control instrumentation. Moreover, a dedicated test of the WEP has not been performed below the millimeter scale. This talk will discuss the improved sensitivity that we expect to achieve in short-range gravity tests with respect to previous efforts that employ different experimental configurations. [Preview Abstract] |
Saturday, November 12, 2011 1:24PM - 1:36PM |
F4.00003: Cosmological models with non-minimal derivative coupling Sergey Sushkov We investigate cosmological scenarios with a non-minimal derivative coupling between the scalar field and the curvature, examining both the quintessence and the phantom cases with zero and constant potentials. In general, we find that the universe transits from one de Sitter solution to another, determined by the coupling parameter. Furthermore, according to the parameter choices and without the need for matter, we can obtain a Big Bang, an expanding universe with no beginning, a cosmological turnaround, an eternally contracting universe, a Big Crunch, a Big Rip avoidance and a cosmological bounce. This variety of behaviors reveals the capabilities of the present scenario. [Preview Abstract] |
Saturday, November 12, 2011 1:36PM - 1:48PM |
F4.00004: Entropic derivation of F=ma for circular motion Michael Duncan, Douglas Singleton, Ratbay Myrzakulov We examine the entropic picture of Newton's second law for the case of circular motion. It is shown that one must make modifications to the derivation of F = ma due to a change in the effective Unruh temperature for circular motion. These modifications present a challenge to the entropic derivation of Newton's second law, but also open up the possibility to experimentally test and constrain this model for large centripetal accelerations. (Phys. Lett. B 703 (2011) 516-518) [Preview Abstract] |
Saturday, November 12, 2011 1:48PM - 2:00PM |
F4.00005: Phase transitions: from liquid-vapor to black holes -- a unified picture Sujoy Modak Conventional thermodynamics identify liquid to vapor phase transitions as a first order transition. Starting from the definition of the Gibbs free energy one obtains Clausius-Clapeyron equation which is satisfied for such a first order phase transition. Similarly for a second order phase transition Ehrenfest relations are satisfied. In this talk we implement these elementary ideas in black holes defined in anti-deSitter space. For charged as well as rotating black holes we show that there exists a phase transition from lower to higher mass (horizon-radius) branch which is not first order. We then derive and check the validity of Ehrenfest relations for these black holes. Our analysis proves that this is a second order phase transition. This result is also verified by using an alternative thermodynamic-state-space geometry approach. [Preview Abstract] |
Saturday, November 12, 2011 2:00PM - 2:12PM |
F4.00006: A conflict of quantum predictions related to the equivalence principle Steve Wilburn, Doug Singleton We compare the response function of an Unruh-DeWitt detector for different space-times and different vacua and show that there is a {\it detailed} violation of the equivalence principle. In particular comparing the response of an accelerating detector to a detector at rest in a Schwarzschild space-time we find that both detectors register thermal radiation, but for a given acceleration the fixed detector in the Schwarzschild space-time measures a higher temperature. This allows one to locally distinguish the two cases. As one approaches the horizon the two temperatures have the same limit so that the equivalence principle is restored at the horizon. [Preview Abstract] |
Saturday, November 12, 2011 2:12PM - 2:24PM |
F4.00007: Challenging Entropic Gravity Jonathan Roveto A recent proposal by Erik Verlinde claims that gravity should be viewed not as a fundamental force, but an emergent thermodynamic phenomenon due to some yet undetermined microscopic theory. We present a challenge to this reformulation of gravity. Our claim is that a detailed derivation using Verlinde's proposed theory fails to correctly give Newton's laws or Einstein gravity. [Preview Abstract] |
Saturday, November 12, 2011 2:24PM - 2:36PM |
F4.00008: On the Energy Source of the Gravitational Field Alexander Mayer According to the principles of special relativity, the systemic energy budget of a quantum harmonic oscillator exceeds canonical ``total energy" ($E$) by the difference between the $\ell^1$-norm and $\ell^2$-norm ($E$) of the complex number $(mc^2 + ipc)$. This surplus energy manifests as a spatially unbounded continuous waveform centered on the source particle, having a phase velocity equal to the speed of light. In the immediate vicinity of a source particle and at corresponding high radial amplitude variation, the interaction between this waveform and spacetime induces various quantum effects. A kilogram of mass contains $\sim\!\!10^{27}$ subatomic harmonic oscillators (e.g., quarks); decoherent superposition of their momentum-driven $(\hbar/\Delta x)$ radiated waveforms provides an isotropic monotonically-decreasing space energy density. Spacetime response to the presence of this distributed energy manifests as the gravitational field in accord with the basic interpretation of general relativity: ``energy curves spacetime.'' \textit{Hypotheses put forward in this discussion are empirically testable with tabletop experiments.} [Preview Abstract] |
Saturday, November 12, 2011 2:36PM - 2:48PM |
F4.00009: A Physical Model for Gravitation and Inertia Ned Rasor A physical/analytical model of gravitation and inertia is described. The model is based on proportional expansion of the universe and its contents, along with special relativistic time delay within nucleons. An expression of the gravitational constant $G$ is derived from the model in terms of fundamental constants and properties without adjustable parameters, \[ G=\frac{he^2}{c^2{\kern 1pt}{\kern 1pt}\tau _u (m_p m_e )^{3/2}}=6.67\times 10^{-8}\frac{cm^3}{g\cdot s^2} \] where h = Planck constant, e = electronic charge, c = speed of light, m$_{p}$ and m$_{e}$ are the nucleonic and electronic masses, and $\tau _u $= age of the universe. The value $\tau _u $ = 13.6 Gy that corresponds with the accepted value of $G$ shown is within the uncertainty of the empirical value of$\tau _u $ currently estimated from cosmic ray background and other astronomical data. A modified Newtonian dynamics and other relationships derived from the model are consistent quantitatively and functionally with a variety of observed astronomical data, some of which have been considered previously to be anomalous or based on dark matter. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2019 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
1 Research Road, Ridge, NY 11961-2701
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700