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What Is Gravity Probe B? a Quest for Experimental Truth the GP-B Flight
What is Gravity Probe B? than Gravity Probe B. It’s just a star, a telescope, and a spinning sphere.” However, it took the exceptional collaboration of Stanford, Gravity Probe B (GP-B) is a NASA physics mission to experimentally MSFC, Lockheed Martin and a host of others more than four decades investigate Einstein’s 1916 general theory of relativity—his theory of gravity. to develop the ultra-precise gyroscopes and the other cutting- GP-B uses four spherical gyroscopes and a telescope, housed in a satellite edge technologies necessary to carry out this “simple” experiment. orbiting 642 km (400 mi) above the Earth, to measure, with unprecedented accuracy, two extraordinary effects predicted by the general theory of rela- The GP-B Flight Mission & Data Analysis tivity: 1) the geodetic effect—the amount by which the Earth warps the local spacetime in which it resides; and 2) the frame-dragging effect—the amount On April 20, 2004 at 9:57:24 AM PDT, a crowd of over 2,000 current and by which the rotating Earth drags its local spacetime around with it. GP-B former GP-B team members and supporters watched and cheered as the tests these two effects by precisely measuring the precession (displacement) GP-B spacecraft lifted off from Vandenberg Air Force Base. That emotionally angles of the spin axes of the four gyros over the course of a year and com- overwhelming day, culminating with the extraordinary live video of paring these experimental results with predictions from Einstein’s theory. the spacecraft separating from the second stage booster meant, as GP-B Program Manager Gaylord Green put it, “that 10,000 things went right.” A Quest for Experimental Truth Once in orbit, the spacecraft first underwent a four-month Initialization The idea of testing general relativity with orbiting gyroscopes was sug- and Orbit Checkout (IOC), in which all systems and instruments were gested independently by two physicists, George Pugh and Leonard Schiff, initialized, tested, and optimized for the data collection to follow. -
Global Program
PROGRAM Monday morning, July 13th La Sapienza Roma - Aula Magna 09:00 - 10:00 Inaugural Session Chairperson: Paolo de Bernardis Welcoming addresses Remo Ruffini (ICRANet), Yvonne Choquet-Bruhat (French Académie des Sciences), Jose’ Funes (Vatican City), Ricardo Neiva Tavares (Ambassador of Brazil), Sargis Ghazaryan (Ambassador of Armenia), Francis Everitt (Stanford University) and Chris Fryer (University of Arizona) Marcel Grossmann Awards Yakov Sinai, Martin Rees, Sachiko Tsuruta, Ken’Ichi Nomoto, ESA (acceptance speech by Johann-Dietrich Woerner, ESA Director General) Lectiones Magistrales Yakov Sinai (Princeton University) 10:00 - 10:35 Deterministic chaos Martin Rees (University of Cambridge) 10:35 - 11:10 How our understanding of cosmology and black holes has been revolutionised since the 1960s 11:10 - 11:35 Group Picture - Coffee Break Gerard 't Hooft (University of Utrecht) 11:35 - 12:10 Local Conformal Symmetry in Black Holes, Standard Model, and Quantum Gravity Plenary Session: Mathematics and GR Katarzyna Rejzner (University of York) 12:10 - 12:40 Effective quantum gravity observables and locally covariant QFT Zvi Bern (UCLA Physics & Astronomy) 12:40 - 13:10 Ultraviolet surprises in quantum gravity 14:30 - 18:00 Parallel Session 18:45 - 20:00 Stephen Hawking (teleconference) (University of Cambridge) Public Lecture Fire in the Equations Monday afternoon, July 13th Code Classroom Title Chairperson AC2 ChN1 MHD processes near compact objects Sergej Moiseenko FF Extended Theories of Gravity and Quantum Salvatore Capozziello, Gabriele AT1 A Cabibbo Cosmology Gionti AT3 A FF3 Wormholes, Energy Conditions and Time Machines Francisco Lobo Localized selfgravitating field systems in the AT4 FF6 Dmitry Galtsov, Michael Volkov Einstein and alternatives theories of gravity BH1:Binary Black Holes as Sources of Pablo Laguna, Anatoly M. -
What Is Gravity Probe B?
What is Gravity Probe B? Gravity Probe B (GP-B) is a NASA physics mission to experimentally in• William Fairbank once remarked: “No mission could be sim• vestigate Einstein’s 1916 general theory of relativity—his theory of gravity. pler than Gravity Probe B. It’s just a star, a telescope, and a spin• GB-B uses four spherical gyroscopes and a telescope, housed in a satellite ning sphere.” However, it took the exceptional collaboration of Stan• orbiting 642 km (400 mi) above the Earth, to measure, with unprecedented ford, MSFC, Lockheed Martin and a host of others more than four accuracy, two extraordinary effects predicted by the general theory of rela• decades to develop the ultra-precise gyroscopes and the other cut• tivity: 1) the geodetic effect—the amount by which the Earth warps the local ting-edge technologies necessary to carry out this “simple” experiment. spacetime in which it resides; and 2) the frame-dragging effect—the amount by which the rotating Earth drags its local spacetime around with it. GP-B tests these two effects by precisely measuring the precession (displacement) The GP-B Flight Mission angles of the spin axes of the four gyros over the course of a year and com• paring these experimental results with predictions from Einstein’s theory. On April 20, 2004 at 9:57:24 AM PDT, a crowd of over 2,000 current and former GP-B team members and supporters watched and cheered as the A Quest for Experimental Truth GP-B spacecraftlift ed offf rom Vandenberg Air Force Base. -
Marcel Grossmann Awards
MG15 MARCEL GROSSMANN AWARDS ROME 2018 ICRANet and ICRA MG XV MARCEL GROSSMANN AWARDS ROME 2018 and TEST The 15th Marcel Grossmann Meeting – MG XV 2nd July 2018, Rome (Italy) Aula Magna – University “Sapienza” of Rome Institutional Awards Goes to: PLANCK SCIENTIFIC COLLABORATION (ESA) “for obtaining important constraints on the models of inflationary stage of the Universe and level of primordial non-Gaussianity; measuring with unprecedented sensitivity gravitational lensing of Cosmic Microwave Background fluctuations by large-scale structure of the Universe and corresponding B- polarization of CMB, the imprint on the CMB of hot gas in galaxy clusters; getting unique information about the time of reionization of our Universe and distribution and properties of the dust and magnetic fields in our Galaxy” - presented to Jean-Loup Puget, the Principal Investigator of the High Frequency Instrument (HFI) HANSEN EXPERIMENTAL PHYSICS LABORATORY AT STANFORD UNIVERSITY “to HEPL for having developed interdepartmental activities at Stanford University at the frontier of fundamental physics, astrophysics and technology” - presented to Research Professor Leo Hollberg, HEPL Assistant Director Individual Awards Goes to LYMAN PAGE “for his collaboration with David Wilkinson in realizing the NASA Explorer WMAP mission and as founding director of the Atacama Cosmology Telescope” Goes to RASHID ALIEVICH SUNYAEV “for the development of theoretical tools in the scrutinising, through the CMB, of the first observable electromagnetic appearance of our Universe” Goes to SHING-TUNG YAU “for the proof of the positivity of total mass in the theory of general relativity and perfecting as well the concept of quasi-local mass, for his proof of the Calabi conjecture, for his continuous inspiring role in the study of black holes physics” Each recipient is presented with a silver casting of the TEST sculpture by the artist A. -
Variable Planck's Constant
Variable Planck’s Constant: Treated As A Dynamical Field And Path Integral Rand Dannenberg Ventura College, Physics and Astronomy Department, Ventura CA [email protected] [email protected] January 28, 2021 Abstract. The constant ħ is elevated to a dynamical field, coupling to other fields, and itself, through the Lagrangian density derivative terms. The spatial and temporal dependence of ħ falls directly out of the field equations themselves. Three solutions are found: a free field with a tadpole term; a standing-wave non-propagating mode; a non-oscillating non-propagating mode. The first two could be quantized. The third corresponds to a zero-momentum classical field that naturally decays spatially to a constant with no ad-hoc terms added to the Lagrangian. An attempt is made to calibrate the constants in the third solution based on experimental data. The three fields are referred to as actons. It is tentatively concluded that the acton origin coincides with a massive body, or point of infinite density, though is not mass dependent. An expression for the positional dependence of Planck’s constant is derived from a field theory in this work that matches in functional form that of one derived from considerations of Local Position Invariance violation in GR in another paper by this author. Astrophysical and Cosmological interpretations are provided. A derivation is shown for how the integrand in the path integral exponent becomes Lc/ħ(r), where Lc is the classical action. The path that makes stationary the integral in the exponent is termed the “dominant” path, and deviates from the classical path systematically due to the position dependence of ħ. -
Variable Planck's Constant
Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 29 January 2021 doi:10.20944/preprints202101.0612.v1 Variable Planck’s Constant: Treated As A Dynamical Field And Path Integral Rand Dannenberg Ventura College, Physics and Astronomy Department, Ventura CA [email protected] Abstract. The constant ħ is elevated to a dynamical field, coupling to other fields, and itself, through the Lagrangian density derivative terms. The spatial and temporal dependence of ħ falls directly out of the field equations themselves. Three solutions are found: a free field with a tadpole term; a standing-wave non-propagating mode; a non-oscillating non-propagating mode. The first two could be quantized. The third corresponds to a zero-momentum classical field that naturally decays spatially to a constant with no ad-hoc terms added to the Lagrangian. An attempt is made to calibrate the constants in the third solution based on experimental data. The three fields are referred to as actons. It is tentatively concluded that the acton origin coincides with a massive body, or point of infinite density, though is not mass dependent. An expression for the positional dependence of Planck’s constant is derived from a field theory in this work that matches in functional form that of one derived from considerations of Local Position Invariance violation in GR in another paper by this author. Astrophysical and Cosmological interpretations are provided. A derivation is shown for how the integrand in the path integral exponent becomes Lc/ħ(r), where Lc is the classical action. The path that makes stationary the integral in the exponent is termed the “dominant” path, and deviates from the classical path systematically due to the position dependence of ħ. -
The Experimental Verdict on Spacetime from Gravity Probe B
The Experimental Verdict on Spacetime from Gravity Probe B James Overduin Abstract Concepts of space and time have been closely connected with matter since the time of the ancient Greeks. The history of these ideas is briefly reviewed, focusing on the debate between “absolute” and “relational” views of space and time and their influence on Einstein’s theory of general relativity, as formulated in the language of four-dimensional spacetime by Minkowski in 1908. After a brief detour through Minkowski’s modern-day legacy in higher dimensions, an overview is given of the current experimental status of general relativity. Gravity Probe B is the first test of this theory to focus on spin, and the first to produce direct and unambiguous detections of the geodetic effect (warped spacetime tugs on a spin- ning gyroscope) and the frame-dragging effect (the spinning earth pulls spacetime around with it). These effects have important implications for astrophysics, cosmol- ogy and the origin of inertia. Philosophically, they might also be viewed as tests of the propositions that spacetime acts on matter (geodetic effect) and that matter acts back on spacetime (frame-dragging effect). 1 Space and Time Before Minkowski The Stoic philosopher Zeno of Elea, author of Zeno’s paradoxes (c. 490-430 BCE), is said to have held that space and time were unreal since they could neither act nor be acted upon by matter [1]. This is perhaps the earliest version of the relational view of space and time, a view whose philosophical fortunes have waxed and waned with the centuries, but which has exercised enormous influence on physics. -
+ Gravity Probe B
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Gravity Probe B Experiment “Testing Einstein’s Universe” Press Kit April 2004 2- Media Contacts Donald Savage Policy/Program Management 202/358-1547 Headquarters [email protected] Washington, D.C. Steve Roy Program Management/Science 256/544-6535 Marshall Space Flight Center steve.roy @msfc.nasa.gov Huntsville, AL Bob Kahn Science/Technology & Mission 650/723-2540 Stanford University Operations [email protected] Stanford, CA Tom Langenstein Science/Technology & Mission 650/725-4108 Stanford University Operations [email protected] Stanford, CA Buddy Nelson Space Vehicle & Payload 510/797-0349 Lockheed Martin [email protected] Palo Alto, CA George Diller Launch Operations 321/867-2468 Kennedy Space Center [email protected] Cape Canaveral, FL Contents GENERAL RELEASE & MEDIA SERVICES INFORMATION .............................5 GRAVITY PROBE B IN A NUTSHELL ................................................................9 GENERAL RELATIVITY — A BRIEF INTRODUCTION ....................................17 THE GP-B EXPERIMENT ..................................................................................27 THE SPACE VEHICLE.......................................................................................31 THE MISSION.....................................................................................................39 THE AMAZING TECHNOLOGY OF GP-B.........................................................49 SEVEN NEAR ZEROES.....................................................................................58 -
Space, Time, and Spacetime
Fundamental Theories of Physics 167 Space, Time, and Spacetime Physical and Philosophical Implications of Minkowski's Unification of Space and Time Bearbeitet von Vesselin Petkov 1. Auflage 2010. Buch. xii, 314 S. Hardcover ISBN 978 3 642 13537 8 Format (B x L): 15,5 x 23,5 cm Gewicht: 714 g Weitere Fachgebiete > Physik, Astronomie > Quantenphysik > Relativität, Gravitation Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. The Experimental Verdict on Spacetime from Gravity Probe B James Overduin Abstract Concepts of space and time have been closely connected with matter since the time of the ancient Greeks. The history of these ideas is briefly reviewed, focusing on the debate between “absolute” and “relational” views of space and time and their influence on Einstein’s theory of general relativity, as formulated in the language of four-dimensional spacetime by Minkowski in 1908. After a brief detour through Minkowski’s modern-day legacy in higher dimensions, an overview is given of the current experimental status of general relativity. Gravity Probe B is the first test of this theory to focus on spin, and the first to produce direct and unambiguous detections of the geodetic effect (warped spacetime tugs on a spin- ning gyroscope) and the frame-dragging effect (the spinning earth pulls spacetime around with it). -
On the Occasion of the 14Th Marcel Grossmann Meeting
ICRANet on the occasion of the 14 th Marcel Grossmann Meeting – MGXIV in celebration of the International Year of Light 2015 the 100 th anniversary of the Einstein’s equations the golden jubilee of Relativistic Astrophysics The ICRANet Seats The University of Rome “La Sapienza” where the Physics Department hosts the ICRANet ICRANet Headquarters in Pescara (Italy). seat in Rome (Italy). ICRANet seat in Nice (France). National Academy of Sciences of Armenia, which hosts the ICRANet seat in Yerevan (Armenia). (Above:) CBPF, which hosts the ICRANet seat in Rio de Janeiro. (Below:) The planned seat at Cassino da Urca (Brazil). II This brochure reviews some background facts concerning the founding of ICRANet and its current structures and then turns to the 2015 celebrations of the Year of Light and the ICRANet initiated International Relativistic Astrophysics Ph.D. program (the IRAP-PhD). It then addresses the birth of relativistic astrophysics following the first fifty years of the existence of general relativity plagued mainly by the absence of observational or experimental activity. Four events marked the onset of relativistic astrophysics: the discovery by Schmidt of the first quasar in 1962, of Scorpius X1 by Riccardo Giacconi in 1963, of the cosmic background radiation by Penzias and Wilson in 1964, and of pulsars by Jocelyn-Bell and Antony Hewish in 1967. These events led to a systematic development of the understanding of the four pillars of relativistic astrophysics: supernovae where observations of the CRAB Nebula are still relevant today, white dwarfs and neutron stars, black holes and their first identification in Nature in Cygnus X1 found by Riccardo Giacconi with the UHURU satellite based on the conceptual background developed by our group in Princeton, and finally the discovery of gamma ray bursts as the largest energy source delivered in the shortest time of any astrophysical phenomenon. -
June 2007 (Volume 16. Number 6) Entire Issue
June 2007 Volume 16, No. 6 www.aps.org/publications/apsnews APS NEWS Our Siberian Correspondent A PUBLICATION OF THE AMERICAN PHYSICAL SOCIETY • WWW.apS.ORG/PUBLICATIONS/apSNEWS International News on page 4 Gender Equity: No Silver Bullet but Lots of Ways to Help Chairs of about 50 major re- over the next 15 years. The gender shop co-chair Arthur Bienenstock search-oriented physics depart- equity conference was organized by of Stanford University said that ments in the United States and APS with support from NSF and given the current US demograph- managers of about 15 physics-re- DOE. ics and increasing competition lated national laboratories met at Women now make up about from other countries in science and the American Center for Physics 13% of physics faculty, but only technology, we need to increase the May 6-8 for a conference entitled 7.9% at top 50 research-oriented proportion of the US workforce en- “Gender Equity: Strengthening the universities. Berrah pointed out gaged in science and technology. To Physics Enterprise in Universities that chemistry and astronomy have do this, we must recruit more wom- and National Laboratories.” twice the percentage of women that en to scientific careers. “If we fail to Photo by Ken Cole The goal of the meeting, accord- physics has. “The gender gap is a increase the participation of women Alice Agogino of UC Berkeley addresses the opening session of the Gender ing to conference co-chair Nora serious concern. We should be talk- we will see a steady decline in the Equity conference. -
Was Einstein Right? Nils Andersson 1905 Special Relativity
Was Einstein right? Nils Andersson 1905 Special Relativity Speed of light is constant, the same for all observers. - Moving clocks run slow - Moving rods appear short - Energy and mass are equivalent... Kyllo/shutterstock Image: Everett Historical/Robert Illustration: Ollie Dean 2015 “Matter tells space how to curve and space tells matter how to move.” John Wheeler Image: Paul Fleet/shutterstock 1907 Gravity; Equivalence principle - moves mass No difference between - bends light acceleration and - warps time gravity. - makes waves - creates black holes 1915 - explains the cosmos General Relativity Gravity is geometry. How do we know this Spacetime is curved. is right? Gravity moves mass 1915: Einstein revolves a long-standing problem mercury concerning the motion of Mercury. The missing 43 arcseconds per century in the perihelion precession is explained by relativity. Image: Albert Einstein archives Gravity bends light Image: Illustrated London News 1919 1919: Predicted light bending tested during solar eclipse, but only at the 30% level... 1955 Unfinished calculations and unanswered questionsLRG 3-757 i) Precision measurements of space and time Image: HST/NASA ii) New telescopes lead to a revolution inImage: Image:astronomy Karen ESA/NASA Teramura iii) Better understanding of the theory Image: Ralph Morse/Getty images 1960 A violent universe 1963: The discovery of quasars opens a window to a very different universe. Cygnus A [NRAO] Crab nebula [NASA] Crab pulsar [Chandra/NASA] Artist’s impression [NASA] Stars run out of fuel and explode in supernovae. Gravity moves mass 1974: PSR B1913+16 Bla2011: Mercury blaha MESSENGER [NASA] 2011: Precision tracking of Mercury provides much tighter constraint.