The Nonsyrnrnetric Gravitational Theory
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Boson Stars: Early History and Recent Prospects
BOSON STARS: EARLY HISTORY AND RECENT PROSPECTSa ECKEHARD W. MIELKEb Departamento de F´ısica, Universidad Aut´onoma Metropolitana–Iztapalapa, Apartado Postal 55-534, C.P. 09340, M´exico, D.F., MEXICO FRANZ E. SCHUNCKc Astronomy Centre, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom Boson stars are descendants of the so–called geons of Wheeler, except that they are built from scalar particles instead of electromagnetic fields. If scalar fields exist in nature, such localized configurations kept together by their self-generated gravitational field can form within Einstein’s general relativity. In the case of complex scalar fields, an absolutely stable branch of such non-topological solitons with conserved particle number exists. Our present surge stems from the speculative possibility that these compact objects could provide a considerable fraction of the non-baryonic part of dark matter. In any case, they may serve as a convenient “laboratory” for studying numerically rapidly rotating bodies in general relativity and the generation of gravitational waves. 1 Introduction If scalar fields exist in nature, soliton-type configurations kept together by their self- generated gravitational field can form absolutely stable boson stars (BS), resembling neutron stars. They are descendants of the so–called geons of Wheeler 140. We will review the history of these hypothetical stars, starting 1968 with the work of Kaup as well as that of Ruffini and Bonazzola. In building macroscopic boson stars, a nonlinear Higgs type potential was later considered as an additional repulsive interaction. Thereby the Kaup limit for boson stars can even exceed the limiting mass of 3.23 M⊙ for neutron stars. -
Is the Universe Expanding?: an Historical and Philosophical Perspective for Cosmologists Starting Anew
Western Michigan University ScholarWorks at WMU Master's Theses Graduate College 6-1996 Is the Universe Expanding?: An Historical and Philosophical Perspective for Cosmologists Starting Anew David A. Vlosak Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses Part of the Cosmology, Relativity, and Gravity Commons Recommended Citation Vlosak, David A., "Is the Universe Expanding?: An Historical and Philosophical Perspective for Cosmologists Starting Anew" (1996). Master's Theses. 3474. https://scholarworks.wmich.edu/masters_theses/3474 This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. IS THEUN IVERSE EXPANDING?: AN HISTORICAL AND PHILOSOPHICAL PERSPECTIVE FOR COSMOLOGISTS STAR TING ANEW by David A Vlasak A Thesis Submitted to the Faculty of The Graduate College in partial fulfillment of the requirements forthe Degree of Master of Arts Department of Philosophy Western Michigan University Kalamazoo, Michigan June 1996 IS THE UNIVERSE EXPANDING?: AN HISTORICAL AND PHILOSOPHICAL PERSPECTIVE FOR COSMOLOGISTS STARTING ANEW David A Vlasak, M.A. Western Michigan University, 1996 This study addresses the problem of how scientists ought to go about resolving the current crisis in big bang cosmology. Although this problem can be addressed by scientists themselves at the level of their own practice, this study addresses it at the meta level by using the resources offered by philosophy of science. There are two ways to resolve the current crisis. -
John A. Wheeler's Lessons to an Undergraduate Student
Phys. Status Solidi C 6, No. 11, 2253–2259 (2009) / DOI 10.1002/pssc.200982051 c solidi pssstatus www.pss-c.com physica current topics in solid state physics John A. Wheeler’s lessons to an undergraduate student Allen P. Mills, Jr.* University of California, Riverside, 92521, USA Received 15 January 2009, accepted 6 February 2009 Published online 16 October 2009 PACS 01.60.+q, 01.65.+g * e-mail [email protected] The author had the good fortune to write his May 1961 Junior ing the paper were preserved and are exhibited here. While research paper “Determination of the Curvature Tensor” un- not valuable scientifically, this material is presented to illus- der the guidance of Professor John Archibald Wheeler (July trate the teaching lavished on an undergraduate and some- 9, 1911 – April 13, 2008). By a series of miraculous mishaps thing about the character and philosophy of the teacher. several of Wheeler’s note sheets as well as his letter critiqu- © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Private lessons I attended Princeton University Hall, upon whose roof Prof. Robert H. Dicke would later and graduated in the Class of 1962. I had the good fortune mount his microwave apparatus for detecting the Big Bang to write my May 1961 Junior research paper “Determina- [4] and his telescope for measuring the oblateness of the tion of the Curvature Tensor” under the guidance of Pro- sun as a test of the Brans-Dicke scalar-tensor gravity the- fessor John Archibald Wheeler (July 9, 1911 – April 13, ory [5]. -
Einstein and Møller Energy-Momentum Distributions for the Static Regular Simpson–Visser Space-Time
S S symmetry Article Einstein and Møller Energy-Momentum Distributions for the Static Regular Simpson–Visser Space-Time Irina Radinschi 1,†, Theophanes Grammenos 2,†, Gargee Chakraborty 3,†, Surajit Chattopadhyay 3,† and Marius Mihai Cazacu 1,*,† 1 Department of Physics, “Gheorghe Asachi” Technical University, 700050 Iasi, Romania; [email protected] 2 Department of Civil Engineering, University of Thessaly, 383 34 Volos, Greece; [email protected] 3 Department of Mathematics, Amity University, Kolkata, Newtown, Kolkata 700135, India; [email protected] (G.C.); [email protected] (S.C.) * Correspondence: [email protected] † These authors contributed equally to this work. Abstract: Energy-momentum localization for the four-dimensional static and spherically symmetric, regular Simpson–Visser black hole solution is studied by use of the Einstein and Møller energy- momentum complexes. According to the particular values of the parameter of the metric, the static Simpson–Visser solution can possibly describe the Schwarzschild black hole solution, a regular black hole solution with a one-way spacelike throat, a one-way wormhole solution with an extremal null throat, or a traversable wormhole solution of the Morris–Thorne type. In both prescriptions it is found that all the momenta vanish, and the energy distribution depends on the mass m, the radial coordinate r, and the parameter a of the Simpson–Visser metric. Several limiting cases of the results Citation: Radinschi, I.; obtained are discussed, while the possibility of astrophysically relevant applications to gravitational Grammenos, T.; Chakraborty, G.; lensing issues is pointed out. Chattopadhyay, S.; Cazacu, M.M. Einstein and Møller Keywords: Energy-Momentum Distributions for Simpson–Visser black hole; energy-momentum localization; Møller energy-momentum; the Static Regular Simpson–Visser Einstein energy-momentum Space-Time. -
Variable Star Section Circular
British Astronomical Association VARIABLE STAR SECTION CIRCULAR No 112, June 2002 Contents Light Curves for some Eclipsing Binary Stars .............................. inside covers From the Director ............................................................................................. 1 Change in E-mail Address for Computer Secretary ......................................... 1 Letters ............................................................................................................... 2 Information on Photometry Available .............................................................. 2 Change to September Circular Deadline .......................................................... 2 The Fade of UY Cen ........................................................................................ 3 Meauring Times of Minimum of EBs using a CCD camera ............................ 4 Photometric Calibration of an MX516 CCD Camera ...................................... 7 Recent Papers on Variable Stars .................................................................... 14 IBVS............................................................................................................... 15 Eclipsing Binary Predictions .......................................................................... 18 ISSN 0267-9272 Office: Burlington House, Piccadilly, London, W1V 9AG PRELIMINARY ECLIPSING BINARY LIGHT CURVES TONY MARKHAM Here are some light curves showing the recent behaviour of some Eclipsing Binaries. The light curves for RZ Cas, Beta -
Chapter 5 Misaligned Spin Axes in the DI Herculis System
Stars and planets at high spatial and spectral resolution Albrecht, S. Citation Albrecht, S. (2008, December 17). Stars and planets at high spatial and spectral resolution. Retrieved from https://hdl.handle.net/1887/13359 Version: Corrected Publisher’s Version Licence agreement concerning inclusion of doctoral thesis in the License: Institutional Repository of the University of Leiden Downloaded from: https://hdl.handle.net/1887/13359 Note: To cite this publication please use the final published version (if applicable). Chapter 5 Misaligned spin axes in the DI Herculis system DI Herculis is one of the most interesting young eclipsing binary systems known. Its apsidal motion, the rotation of the orbit in its own plane, has been measured to be significantly lower (2.9 × 10−4 ± 0.4 · 10−4 ◦/cycle) than the expected value (1.25 · 10−3 ◦/cycle). Until now the reason why its apsidal motion is much slower than theoretically expected escapes a solid explanation. A number of theories have been put forward to explain this apparent discrepancy, including a revision of general relativity. However the underlying calculations are based on the premise of co-aligned stellar rotation axes. To test this assumption we observed the DI Herculis system during both primary and secondary eclipse with the high resolution Echelle spectrograph Sophie of the Oberserva- torie de Haute Provence. Using our newly developed analysis tools (Chapter 4) we find a strong misalignment be- tween the projections of the stellar spin axes and the orbital spin axis on the sky. The angle between, the projected stellar spin axes and the projected orbital spin axis is (71 ± 4◦) for the primary and (93 ± 8◦) for the secondary. -
COMMISSIONS 27 and 42 of the I.A.U. INFORMATION BULLETIN on VARIABLE STARS Nos. 4101{4200 1994 October { 1995 May EDITORS: L. SZ
COMMISSIONS AND OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Nos Octob er May EDITORS L SZABADOS and K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI KONKOLY OBSERVATORY H BUDAPEST PO Box HUNGARY IBVSogyallakonkolyhu URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN 2 CONTENTS 1994 No page E F GUINAN J J MARSHALL F P MALONEY A New Apsidal Motion Determination For DI Herculis ::::::::::::::::::::::::::::::::::::: D TERRELL D H KAISER D B WILLIAMS A Photometric Campaign on OW Geminorum :::::::::::::::::::::::::::::::::::::::::::: B GUROL Photo electric Photometry of OO Aql :::::::::::::::::::::::: LIU QUINGYAO GU SHENGHONG YANG YULAN WANG BI New Photo electric Light Curves of BL Eridani :::::::::::::::::::::::::::::::::: S Yu MELNIKOV V S SHEVCHENKO K N GRANKIN Eclipsing Binary V CygS Former InsaType Variable :::::::::::::::::::: J A BELMONTE E MICHEL M ALVAREZ S Y JIANG Is Praesep e KW Actually a Delta Scuti Star ::::::::::::::::::::::::::::: V L TOTH Ch M WALMSLEY Water Masers in L :::::::::::::: R L HAWKINS K F DOWNEY Times of Minimum Light for Four Eclipsing of Four Binary Systems :::::::::::::::::::::::::::::::::::::::::: B GUROL S SELAN Photo electric Photometry of the ShortPeriod Eclipsing Binary HW Virginis :::::::::::::::::::::::::::::::::::::::::::::: M P SCHEIBLE E F GUINAN The Sp otted Young Sun HD EK Dra ::::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::: M BOS Photo electric Observations of AB Doradus ::::::::::::::::::::: YULIAN GUO A New VR Cyclic Change of H in Tau :::::::::::::: -
Massive Graviton Geons
PHYSICAL REVIEW D 97, 044005 (2018) Massive graviton geons † ‡ Katsuki Aoki,1,* Kei-ichi Maeda,1, Yosuke Misonoh,1, and Hirotada Okawa2,1,§ 1Department of Physics, Waseda University, Shinjuku, Tokyo 169-8555, Japan 2Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan (Received 24 October 2017; published 5 February 2018) We find vacuum solutions such that massive gravitons are confined in a local spacetime region by their gravitational energy in asymptotically flat spacetimes in the context of the bigravity theory. We call such self-gravitating objects massive graviton geons. The basic equations can be reduced to the Schrödinger- Poisson equations with the tensor “wave function” in the Newtonian limit. We obtain a nonspherically symmetric solution with j ¼ 2, l ¼ 0 as well as a spherically symmetric solution with j ¼ 0, l ¼ 2 in this system where j is the total angular momentum quantum number and l is the orbital angular momentum quantum number, respectively. The energy eigenvalue of the Schrödinger equation in the nonspherical solution is smaller than that in the spherical solution. We then study the perturbative stability of the spherical solution and find that there is an unstable mode in the quadrupole mode perturbations which may be interpreted as the transition mode to the nonspherical solution. The results suggest that the nonspherically symmetric solution is the ground state of the massive graviton geon. The massive graviton geons may decay in time due to emissions of gravitational waves but this timescale can be quite long when the massive gravitons are nonrelativistic and then the geons can be long-lived. -
Static Electromagnetic Geon
Foundations of Physics, VoL 16, No. 2, 1986 Static Electromagnetic Geon Marek Demianski 1 Received August 6, 1985 A static, spherically symmetric, and asymptotically fiat solution of coupled Einstein-Born-Infeld equations is presented. When the internal mass of the system is zero the resulting space-time is regular and describes static electromagnetic geon. Early in the fifties John Wheeler introduced the notion of an elec- tromagnetic geon(1): In the Einstein Maxwell theory an electromagnetic geon is formed of electromagnetic radiation held together by mutual gravitational attraction. The gravitational field and the electromagnetic field of a geon is regular everywhere. Here we would like to show that there is a spherically symmetric static solution of the Einstein field equation coupled with the nonlinear Born-In- feld electrodynamics, which is regular everywhere. The space-time is described by a spherically symmetric line element as 2 = e ~ at 2 -- e ~ dr 2 -- r2(dO 2 q- sin 2 0 d~ 2 ) (1) where v and 2 are functions of r only. The electromagnetic field is determined by an antisymmetric tensor Fu~, which is related in the usual way to the covariant potential A~, Fuv=Av,~-A,,v. The electric and magnetic fields are defined by the relations E a = F, vu~ZVVa, B ~ = -F~u~v~ v (2) 1 Institute for Theoretical Physics, University of Warsaw, Warsaw, Poland, and Center for Theoretical Physics, University of Texas Austin, Texas 78712. 187 0015-9018/86/0200-0187505.00/0 © 1986 Plenum PublishingCorporation 188 Demianski where F ~v is the dual tensor to F 'v, u ~' is the four velocity of an observer, and v~ are three orthonormal spacelike vectors. -
Abstracts of All Scientific Papers Since 1989
ABSTRACTS FROM SCIENTIFIC PAPERS GRAVITY PROBE B RELATIVITY MISSION Stanford University 1989 M. P. Reisenberger, et al., “A Possible Rescue of General Relativity in Di Herculis,” Astronomical Journal 97, pp. 216-221, 1989. Abstract: The binary DI Her has attracted attention because its low observed rate of apsidal advance, dw/dt = 1.0° ± 0.3°/100yr, appears to contradict general relativity, which seems to require dw/dt = 4.3° ± 0.3°/100 yr. We present very tentative evidence in support of the hypothesis (advanced by Shakura) that the stars are rotating about axes highly inclined to the orbital axis. If the inclination of a component is > 54.7°, then its rotational distortion will slow the apsidal advance. From rather sparse data, we calculate dw/dt = 0.7° ± 2.0°/100 yr. Two measurements that could help settle the issue are proposed. Both could be done easily by an observer with access to a fairly large(>50 in.) telescope and a CCD spectrograph. P. Axelrad, B. W. Parkinson, “Closed Loop Navigation and Guidance for Gravity Probe B Orbit Insertion,” Journal of The Institute of Navigation, Vol. 36, No. 1, Spring 1989. Abstract: This paper addresses the problem of guiding the Gravity Probe B (GP-B) spacecraft from its location after initial insertion to a very precise low earth orbit. Specifically, the satellite orbit is required to be circular to within 0.001 eccentricity, polar to within 0.001 deg inclination, and aligned with the direction of the star Rigel to within 0.001 deg. Navigation data supplied by an on-board GPS receiver is used as feedback to a control algorithm designed to minimize the time to achieve the desired orbit. -
Compact Stars in the Nonsymmetric Gravitational Theory by Lyle
Compact Stars in the Nonsymmetric Gravitational Theory by Lyle McLean Campbell A Thesis submitted in conformity with the requirements for the Degree of Doctor of Philosophy in the University of Toronto © Lyle McLean Campbell 1988 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Abstract Stable white dwarfs and neutron stars axe shown to exist in the Nonsym- metric Gravitational Theory (NGT). They are modelled as static spherically symmetric bodies of charge-neutral perfect fluid matter, with standard equa tions of state. The particle number model for the NGT conserved current, S 11, is used. The effects of NGT reduce the stability of these compact stars com pared to similar stars modelled using General Relativity or Newtonian grav ity. There is a decrease in the maximum mass of both white dwarfs and neutron stars. The central densities are greater and the radii are smalls- In all these ways, it can be seen that NGT produces a greater gravitational force in compact stars than General Relativity. NGT also decreases the surface gravitational redshift. From examination of the solutions for compact stars, constraints are placed on the £2 charges, (/" -f/") and f 2, of protons, neutrons and electrons. If matter composed only of these particles is considered, the constraints keep the £2 charge of the Sim so small that the NGT effects it produces in the solar system are unobservable at present. Similarly, the NGT terms in the periastron precession of eclipsing binary star systems, such as DI Herculis, would be so small that NGT could not explain the anomalies found there. -
Misaligned Spin and Orbital Axes Cause the Anomalous Precession of DI Herculis
Misaligned spin and orbital axes cause the anomalous precession of DI Herculis The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Albrecht, Simon et al. “Misaligned spin and orbital axes cause the anomalous precession of DI[thinsp]Herculis.” Nature 461.7262 (2009): 373-376. © 2009 Nature Publishing Group. As Published http://dx.doi.org/10.1038/nature08408 Publisher Nature Publishing Group Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/58482 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. Albrecht et al. (2009), Nature, in press Misaligned spin and orbital axes cause the anomalous precession of DI Herculis* Simon Albrecht†,‡, Sabine Reffert§, Ignas A.G. Snellen†, & Joshua N. Winn‡ The orbits of binary stars precess as a result of general relativistic effects, forces arising from the asphericity of the stars, and forces from additional stars or planets in the system. For most binaries, the theoretical and observed precession rates are in agreement1. One system, however—DI Herculis—has resisted explanation for 30 years2–4. The observed precession rate is a factor of four slower than the theoretical rate, a disagreement that once was interpreted as evidence for a failure of general relativity5. Among the contemporary explanations are the existence of a circumbinary planet6 and a large tilt of the stellar spin axes with respect to the orbit7,8. Here we report that both stars of DI Herculis rotate with their spin axes nearly perpendicular to the orbital axis (contrary to the usual assumption for close binary stars).