China's First Step Towards Probing the Expanding Universe and the Nature of Gravity Using a Space Borne Gravitational Wave
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Spacetime, Ontology, and Structural Realism Edward Slowik
International Studies in the Philosophy of Science Vol. 19, No. 2, July 2005, pp. 147–166 Spacetime, Ontology, and Structural Realism Edward Slowik TaylorCISP124928.sgm10.1080/02698590500249456International0269-8595Original2005Inter-University192000000JulyEdwardSlowikDepartmenteslowik@winona.edu and Article (print)/1469-9281Francis 2005of Studies PhilosophyWinona Foundation Ltd in the Philosophy (online) State of UniversityWinonaMN Science 55987-5838USA This essay explores the possibility of constructing a structural realist interpretation of spacetime theories that can resolve the ontological debate between substantivalists and relationists. Drawing on various structuralist approaches in the philosophy of mathemat- ics, as well as on the theoretical complexities of general relativity, our investigation will reveal that a structuralist approach can be beneficial to the spacetime theorist as a means of deflating some of the ontological disputes regarding similarly structured spacetimes. 1. Introduction Although its origins can be traced back to the early twentieth century, structural real- ism (SR) has only recently emerged as a serious contender in the debates on the status of scientific entities. SR holds that what is preserved in successive theory change is the abstract mathematical or structural content of a theory, rather than the existence of its theoretical entities. Some of the benefits that can be gained from SR include a plausible account of the progressive empirical success of scientific theorizing (thus avoiding the ‘no miracles’ -
Mapping Weak Gravitational Lensing Signals from Low-Redshift Galaxy Clusters to Compare Dark Matter and X-Ray Gas Substructures
MAPPING WEAK GRAVITATIONAL LENSING SIGNALS FROM LOW-REDSHIFT GALAXY CLUSTERS TO COMPARE DARK MATTER AND X-RAY GAS SUBSTRUCTURES. CLAIRE HAWKINS BROWN UNIVERSITY MAY 2020 1 Contents Acknowledgements: ...................................................................................................................................... 3 Abstract: ........................................................................................................................................................ 4 Introduction: .................................................................................................................................................. 5 Background: .................................................................................................................................................. 7 GR and Gravitational Lensing .................................................................................................................. 7 General Relativity ................................................................................................................................. 7 Gravitational Lensing ............................................................................................................................ 9 Galaxy Clusters ....................................................................................................................................... 11 Introduction to Galaxy Clusters ......................................................................................................... -
Globular Clusters and Galactic Nuclei
Scuola di Dottorato “Vito Volterra” Dottorato di Ricerca in Astronomia– XXIV ciclo Globular Clusters and Galactic Nuclei Thesis submitted to obtain the degree of Doctor of Philosophy (“Dottore di Ricerca”) in Astronomy by Alessandra Mastrobuono Battisti Program Coordinator Thesis Advisor Prof. Roberto Capuzzo Dolcetta Prof. Roberto Capuzzo Dolcetta Anno Accademico 2010-2011 ii Abstract Dynamical evolution plays a key role in shaping the current properties of star clus- ters and star cluster systems. We present the study of stellar dynamics both from a theoretical and numerical point of view. In particular we investigate this topic on different astrophysical scales, from the study of the orbital evolution and the mutual interaction of GCs in the Galactic central region to the evolution of GCs in the larger scale galactic potential. Globular Clusters (GCs), very old and massive star clusters, are ideal objects to explore many aspects of stellar dynamics and to investigate the dynamical and evolutionary mechanisms of their host galaxy. Almost every surveyed galaxy of sufficiently large mass has an associated group of GCs, i.e. a Globular Cluster System (GCS). The first part of this Thesis is devoted to the study of the evolution of GCSs in elliptical galaxies. Basing on the hypothesis that the GCS and stellar halo in a galaxy were born at the same time and, so, with the same density distribution, a logical consequence is that the presently observed difference may be due to evolution of the GCS. Actually, in this scenario, GCSs evolve due to various mechanisms, among which dynamical friction and tidal interaction with the galactic field are the most important. -
On the Quantization of Burgers Vector and Gravitational Energy in the Space-Time of a Conical Defect
On the Quantization of Burgers Vector and Gravitational Energy in the Space-Time of a Conical Defect 1, 1, 2, 3, 1, 1, F. L. Carneiro, ∗ S. C. Ulhoa, y J. F. da Rocha-Neto, z and J. W. Maluf x 1Instituto de F´ısica, Universidade de Bras´ılia, 70910-900, Bras´ılia, DF, Brazil 2International Center of Physics, Instituto de F´ısica, Universidade de Bras´ılia, 70.910-900, Brasilia, DF, Brazil 3Canadian Quantum Research Center, 204-3002 32 Ave Vernon, BC V1T 2L7 Canada A conical topological defect is the result of translational and/or rotational deformations of spacetime, in particular the Burgers vector describes the translational deformation. Such a configuration represents a discontinuity, that cannot be removed by coordinate trans- formations, and is related to the spacetime torsion. Using the Teleparallel Equivalent of General Relativity (TERG), a gravitational theory that is dynamically equivalent to Gen- eral Relativity (GR), we investigate the consequences of assuming a discrete Burgers vector on the geodesic motion of particles around a static conical defect. The result is a helical geodesic motion of a test particle around the defect, with a discrete step that depends on the magnitude of the dislocation. I. INTRODUCTION Defects in crystals and metals may occur in three forms: point, linear or planar defects. The linear defects are caused by translational (dislocation) or rotational (disclination) distortions. It was soon realized that such defects in a lattice could be applied to gravitation. For instance, cosmic strings can be interpreted as topological defects in spacetime [1–3]. The more general spacetime defects solutions were constructed using the Volterra process [4] by Puntingam and Soleng [5]. -
Introductory Particle Cosmology
Introductory Particle Cosmology Luca Doria Institut für Kernphysik Johannes-Gutenberg Universität Mainz Lecture 1 Introduction Mathematical Tools Generic Vector Bases Observation Basis Change Cosmology CMB Vectors in Curved Geometries Cosmological Principle Structure Formation Tensors, Metric Tensor FLRW Metric Red-shift/Distance (Riemann) Manifolds Friedmann Equations Connection Cosmic Distances Geodesics and Curvature Cosmological Models Particle Cosmology General Relativity Dark Matter (Models + Exp.) Equivalence Principle Dark Energy (Models + Exp) Einstein Equations Inflationary Models Standard Model Gravitational Waves Density Perturbations Brief History Particle Content Gauge Principle, CPV, Strong CP EW Symmetry Breaking Beyond the SM Notes and Slides: www.staff.uni-mainz.de/doria/partcosm.html Sommersemester 2018 Luca Doria, JGU Mainz 2 Plan Datum Von Bis Raum 1 Di, 17. Apr. 2018 10:00 12:00 05 119 Minkowski-Raum 2 Do, 19. Apr. 2018 08:00 10:00 05 119 Minkowski-Raum 3 Di, 24. Apr. 2018 10:00 12:00 05 119 Minkowski-Raum 4 Do, 26. Apr. 2018 08:00 10:00 05 119 Minkowski-Raum 5 Do, 3. Mai 2018 08:00 10:00 05 119 Minkowski-Raum 6 Di, 8. Mai 2018 10:00 12:00 05 119 Minkowski-Raum 7 Di, 15. Mai 2018 10:00 12:00 05 119 Minkowski-Raum 8 Do, 17. Mai 2018 08:00 10:00 05 119 Minkowski-Raum H.Minkowski 9 Di, 22. Mai 2018 10:00 12:00 05 119 Minkowski-Raum (1864-1909) 10 Do, 24. Mai 2018 08:00 10:00 05 119 Minkowski-Raum 11 Di, 29. Mai 2018 10:00 12:00 05 119 Minkowski-Raum 12 Di, 5. -
Women of Goddard: Careers in Science, Technology, Engineering, and Mathematics
Women of Goddard: Careers in Science, Technology, Engineering, and Mathematics Engineering, Technology, Careers in Science, of Goddard: Women National Aeronautics and Space Administration Goddard of Parkinson, Millar, Thaller Millar, Parkinson, Careers in Science Technology Engineering & Mathematics Women www.nasa.gov Women of Goddard NASA’s Goddard Space Flight Center IV&V, WV Goddard Institute for Space Studies, Greenbelt, Maryland, Main Campus Wallops Flight Facility, Virginia New York City Testing and Integration Facility, Greenbelt Home of Super Computing and Data Storage, Greenbelt GSFC’s new Sciences and Exploration Building, Greenbelt Women of Goddard: Careers in Science, Technology, Engineering, and Mathematics Editors: Claire L. Parkinson, Pamela S. Millar, and Michelle Thaller Graphics and Layout: Jay S. Friedlander In Association with: The Maryland Women’s Heritage Center (MWHC) NASA Goddard Space Flight Center, Greenbelt, Maryland, July 2011 Women of Goddard Careers in Foreword Science A century ago women in the United States could be schoolteachers and nurses but were largely excluded from the vast majority of other jobs that could Technology be classified as Science, Technology, Engineering, or Mathematics (STEM careers). Some inroads were fortuitously made during World Wars I and II, when because of Engineering the number of men engaged in fighting overseas it became essential that women fill in on jobs of all types on the home front. However, many of these inroads Mathematics were lost after the wars ended and the men -
Progress in Nuclear Astrophysics of East and Southeast Asia
Aziz et al. AAPPS Bulletin (2021) 31:18 AAPPS Bulletin https://doi.org/10.1007/s43673-021-00018-z Review article Open Access Progress in nuclear astrophysics of east and southeast Asia Azni Abdul Aziz1, Nor Sofiah Ahmad2,S.Ahn3,WakoAoki4, Muruthujaya Bhuyan2, Ke-Jung Chen5,Gang Guo6,7,K.I.Hahn8,9, Toshitaka Kajino4,10,11*, Hasan Abu Kassim2,D.Kim12, Shigeru Kubono13,14, Motohiko Kusakabe11,15,A.Li15, Haining Li16,Z.H.Li17,W.P.Liu17*,Z.W.Liu18, Tohru Motobayashi14, Kuo-Chuan Pan19,20,21,22, T.-S. Park12, Jian-Rong Shi16,23, Xiaodong Tang24,25* ,W.Wang26,Liangjian Wen27, Meng-Ru Wu5,6, Hong-Liang Yan16,23 and Norhasliza Yusof2 Abstract Nuclear astrophysics is an interdisciplinary research field of nuclear physics and astrophysics, seeking for the answer to a question, how to understand the evolution of the universe with the nuclear processes which we learn. We review the research activities of nuclear astrophysics in east and southeast Asia which includes astronomy, experimental and theoretical nuclear physics, and astrophysics. Several hot topics such as the Li problems, critical nuclear reactions and properties in stars, properties of dense matter, r-process nucleosynthesis, and ν-process nucleosynthesis are chosen and discussed in further details. Some future Asian facilities, together with physics perspectives, are introduced. Keywords: Nuclear astrophysics, East and southeast Asia 1 Introduction • What are the nuclear reactions that drive the Nuclear astrophysics deals with astronomical phenomena evolution of stars and stellar explosions? involving atomic nuclei, and therefore, it is an interdis- ciplinary field that consists of astronomy, astrophysics, The research involves close collaboration among and nuclear physics. -
Form + Function: Optimizing Aesthetic Product Design Via Adaptive, Geometrized Preference Elicitation
Form + Function: Optimizing Aesthetic Product Design via Adaptive, Geometrized Preference Elicitation Namwoo Kang ,* Yi Ren ,† Fred Feinberg ,‡ and Panos Papalambros § Abstract Visual design is critical to product success, and the subject of intensive marketing research effort. Yet visual elements, due to their holistic and interactive nature, do not lend themselves well to optimization using extant decompositional methods for preference elicitation. Here we present a systematic methodology to incorporate interactive, 3D-rendered product configurations into a conjoint-like framework. The method relies on rapid, scalable machine learning algorithms to adaptively update product designs along with standard information-oriented product attributes. At its heart is a parametric account of a product’s geometry, along with a novel, adaptive “bi- level” query task that can estimate individuals’ visual design form preferences and their trade-offs against such traditional elements as price and product features. We illustrate the method’s perfor- mance through extensive simulations and robustness checks, a formal proof of the bi-level query methodology’s domain of superiority, and a field test for the design of a mid-priced sedan, us- ing real-time 3D rendering for an online panel. Results indicate not only substantially enhanced predictive accuracy, but two quantities beyond the reach of standard conjoint methods: trade-offs between form and function overall, and willingness-to-pay for specific design elements. More- arXiv:1912.05047v1 [cs.HC] 10 Dec 2019 over – and most critically for applications – the method provides “optimal” visual designs for both individuals and model-derived or analyst-supplied consumer groupings, as well as their sensitivities to form and functional elements. -
Arxiv:2108.11151V1 [Gr-Qc] 25 Aug 2021 Aee Siain 2,27]
Alternative LISA-TAIJI networks: detectability to isotropic stochastic gravitational wave background Gang Wang1, ∗ and Wen-Biao Han1, 2, 3, † 1Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 2Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310124, China 3School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China (Dated: August 26, 2021) In previous work [1], three TAIJI orbital deployments have been proposed to compose alternative LISA-TAIJI networks, TAIJIm (leading the Earth by 20◦ and −60◦ inclined with respect to ecliptic plane), TAIJIp (leading the Earth by 20◦ and +60◦ inclined), TAIJIc (colocated and coplanar with LISA) with respect to LISA mission (trailing the Earth by 20◦ and +60◦ inclined). And the LISA-TAIJIm network has been identified as the most capable configuration for massive black hole binary observation. In this work, we examine the performance of three networks to the stochastic gravitational wave background (SGWB) especially for the comparison of two eligible configurations, LISA-TAIJIm and LISA-TAIJIp. This investigation shows that the detectability of LISA-TAIJIm is competitive with the LISA-TAIJIp network for some specific SGWB spectral shapes. And the capability of LISA-TAIJIm is also identical to LISA-TAIJIp to separate the SGWB components by determining the parameters of signals. Considering the performances on SGWB and massive black hole binaries observations, the TAIJIm could be recognized as an optimal option to fulfill joint observations with LISA. I. INTRODUCTION In previous work, we proposed three TAIJI orbits to construct LISA-TAIJI networks and investigated their More than fifty gravitational wave (GW) events have performances on sky localizations for MBH binaries, con- been detected during the Advanced LIGO and Ad- straints on polarizations, and overlap reduction functions vanced Virgo observing runs O1-O3a, and all signals [1]. -
Motion Analysis of Particles Using the Hyper-Complex Numbers Representation
Open Access Journal of Mathematical and Theoretical Physics Research Article Open Access Motion analysis of particles using the hyper-complex numbers representation Abstract Volume 2 Issue 1 - 2019 The present contribution uses the Hyper-Complex Numbers model to describe and Vlad L Negulescu analyze the kinematics and dynamics of ideal particles. The analysis extends to super- Dresdener Ring 31 61130 Nidderau, Germany luminal particles and tachyons. The pure particles and pure forces are also defined and discussed. The behavior of pure tardyons and pure tachyons is further presented. Correspondence: Vlad L. Negulescu, Dresdener Ring 31 61130 Nidderau, Germany, Tel 004961872092820, Keywords: H and VH- numbers representation, geometrized unit system, big bang, Email pseudo-rotation, Lorenz transformations, equations of the motion, source, tardyons, tachyons, mass-momentum relationships. Received: February 05, 2019 | Published: February 25, 2019 Introduction and preliminary represents the “physical world” as was defined in the reference.3 The four-dimensional continuous Space Time (ST), or Minkowski space 1–3 In various articles, the author developed a mathematical model modified, is a subset of the physical world. showing interesting applications in mechanics, electromagnetism and quantum behavior. The present paper uses the model to propose a new The geometry of ST was mathematically expressed, and described theory concerning the tachyons. in the reference paper.2 Our universe generally is a vacuum with some celestial bodies at sufficiently large distance, and we can consider The material particle as a VH-number it as a practically empty space. The universe is, according to the 3 last measurements, flat i.e. Euclidean. The estimated density of the According to the article, an ideal particle is represented by a −27 3 Vector-Hyper-Complex number, or VH-number, which is formally universe is approximately 9.9x10 Kg / m . -
Space Activities 2019
Space Activities in 2019 Jonathan McDowell [email protected] 2020 Jan 12 Rev 1.3 Contents Preface 3 1 Orbital Launch Attempts 3 1.1 Launch statistics by country . 3 1.2 Launch failures . 4 1.3 Commercial Launches . 4 2 Satellite Launch Statistics 6 2.1 Satellites of the major space powers, past 8 years . 6 2.2 Satellite ownership by country . 7 2.3 Satellite manufacture by country . 11 3 Scientific Space Programs 11 4 Military Space Activities 12 4.1 Military R&D . 12 4.2 Space surveillance . 12 4.3 Reconnaissance and Signals Intelligence . 13 4.4 Space Weapons . 13 5 Special Topics 13 5.1 The Indian antisatellite test and its implications . 13 5.2 Starlink . 19 5.3 Lightsail-2 . 24 5.4 Kosmos-2535/2536 . 25 5.5 Kosmos-2542/2543 . 29 5.6 Starliner . 29 5.7 OTV-5 and its illegal secret deployments . 32 5.8 TJS-3 . 33 6 Orbital Debris and Orbital Decay 35 6.1 Disposal of launch vehicle upper stages . 36 6.2 Orbituaries . 39 6.3 Retirements in the GEO belt . 42 6.4 Debris events . 43 7 Acknowledgements 43 Appendix 1: 2019 Orbital Launch Attempts 44 1 Appendix 2a: Satellite payloads launched in 2018 (Status end 2019) 46 Appendix 2b: Satellite payloads deployed in 2018 (Revised; Status end 2019) 55 Appendix 2c: Satellite payloads launched in 2019 63 Appendix 2d: Satellite payloads deployed in 2019 72 Rev 1.0 - Jan 02 Initial version Rev 1.1 - Jan 02 Fixed two incorrect values in tables 4a/4b Rev 1.2 - Jan 02 Minor typos fixed Rev 1.3 - Jan 12 Corrected RL10 variant, added K2491 debris event, more typos 2 Preface In this paper I present some statistics characterizing astronautical activity in calendar year 2019. -
Jhep05(2021)160
Published for SISSA by Springer Received: March 4, 2021 Accepted: May 3, 2021 Published: May 19, 2021 Phase transition gravitational waves from pseudo-Nambu-Goldstone dark matter and two Higgs JHEP05(2021)160 doublets Zhao Zhang, Chengfeng Cai, Xue-Min Jiang, Yi-Lei Tang,1 Zhao-Huan Yu1 and Hong-Hao Zhang1 School of Physics, Sun Yat-Sen University, Guangzhou 510275, China E-mail: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected] Abstract: We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting grav- itational wave spectra are further evaluated. Some parameter points are found to induce strong gravitational wave signals, which have the opportunity to be detected in future space-based interferometer experiments LISA, Taiji, and TianQin. Keywords: Beyond Standard Model, Cosmology of Theories beyond the SM, Higgs Physics, Thermal Field Theory ArXiv ePrint: 2102.01588 1Corresponding author. Open Access, c The Authors. https://doi.org/10.1007/JHEP05(2021)160 Article funded by SCOAP3. Contents 1 Introduction1 2 The model2 3 Experimental bounds5 4 Effective potential6 JHEP05(2021)160 5 Phase transitions 10 6 Gravitational wave spectra 14 7 Numerical analyses 16 8 Summary 21 1 Introduction It is conventionally believed that dark matter (DM) originates from thermal production at the early Universe [1–3].