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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. -
Tests of General Relativity - Wikipedia
12/2/2018 Tests of general relativity - Wikipedia Tests of general relativity T ests of general relativity serve to establish observational evidence for the theory of general relativity. The first three tests, proposed by Einstein in 1915, concerned the "anomalous" precession of the perihelion of Mercury, the bending of light in gravitational fields, and the gravitational redshift. The precession of Mercury was already known; experiments showing light bending in line with the predictions of general relativity was found in 1919, with increasing precision measurements done in subsequent tests, and astrophysical measurement of the gravitational redshift was claimed to be measured in 1925, although measurements sensitive enough to actually confirm the theory were not done until 1954. A program of more accurate tests starting in 1959 tested the various predictions of general relativity with a further degree of accuracy in the weak gravitational field limit, severely limiting possible deviations from the theory. In the 197 0s, additional tests began to be made, starting with Irwin Shapiro's measurement of the relativistic time delay in radar signal travel time near the sun. Beginning in 197 4, Hulse, Taylor and others have studied the behaviour of binary pulsars experiencing much stronger gravitational fields than those found in the Solar System. Both in the weak field limit (as in the Solar System) and with the stronger fields present in systems of binary pulsars the predictions of general relativity have been extremely well tested locally. In February 2016, the Advanced LIGO team announced that they had directly detected gravitational waves from a black hole merger.[1] This discovery, along with additional detections announced in June 2016 and June 2017 ,[2] tested general relativity in the very strong field limit, observing to date no deviations from theory. -
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. -
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. -
Searches for the Role of Spin in Gravity
Rotation, Equivalence Principle, and GP-B Experiment Wei-Tou Ni1,2 1Shanghai United Center for Astrophysics (SUCA), Shanghai Normal University, Shanghai 200234, China 2Center for Gravitation and Cosmology, Department of Physics, National Tsing Hua University, Hsinchu, Taiwan, 30013, ROC (Received 22 May, 2011) Abstract The ultra-precise Gravity Probe B experiment measured the frame-dragging effect and geodetic precession on four quartz gyros. We use this result to test WEP II (Weak Equivalence Principle II) which includes rotation in the universal free-fall motion. The free-fall Eötvös parameter η for rotating body is ≤ 10-11 with four-order improvement over previous results. The anomalous torque per unit angular momentum parameter λ is constrained to (-0.05 ± 3.67) × 10−15 s−1, (0.24 ± 0.98) × 10−15 s−1, and (0 ± 3.6) ×10−13 s−1 respectively in the directions of geodetic effect, frame-dragging effect and angular momentum axis; the dimensionless frequency-dependence parameter κ is constrained to (1.75 ± 4.96) × 10-17, (1.80 ± 1.34) × 10-17, and (0 ± 3) ×10−14 respectively. 1 Equivalence principles [1, 2, 3] are cornerstones in the foundation of gravitation theories. Galilei Equivalence Principle states that test bodies with the same initial position and initial velocity fall in the same way in a gravitational field. This principle is also called Universality of Free Fall (UFF) or Weak Equivalence Principle (WEP). Since a macroscopic test body has 3 translational and 3 rotational degrees of freedom, true equivalence must address to all six degrees of freedom. We propose a second Weak Equivalence Principle (WEP II) to be tested by experiments. -
Gravity Probe B Data Confirms Frame-Dragging and Geodetic
Gravity Probe B Data Confirms Frame-Dragging and Geodetic Effect in Support of Eins... http://www.lockheedmartin.com/news/press_releases/2011/0504_ss_GPB.html Home | Contact Us Search: Follow | Capabilities Global Products About Us Careers Investor Relations News Suppliers News Home > News Email Alerts Employee News Room Feature Stories LM Today Newsletter Gravity Probe B Data Confirms Frame-Dragging and Geodetic Effect in Photo Gallery Support of Einstein’s General Theory of Relativity Press Contacts Press Releases SUNNYVALE, Calif., May 4th, 2011 -- Launched on April 20, 2004, Gravity Probe B (GP-B) gathered data Speeches during its 16-month mission that have now provided verification for two subtle physical effects predicted by Video Albert Einstein’s General Theory of Relativity, which provides the foundation for an understanding of the large-scale structure of the Universe. The geodetic effect—the warping of Earth’s local space-time due to Earth’s mass––has been confirmed to 0.28% accuracy. The frame-dragging effect—the dragging or twisting of Earth’s local space-time due to Earth’s rotation––has been confirmed to 19% accuracy. Stanford University was the GP-B prime contractor, NASA’s GP-B space vehicle was built, integrated and tested by Lockheed Martin (NYSE:LMT) at its Space Systems Company facility in Sunnyvale, Calif., and NASA Marshall Space Flight Center in Huntsville, Ala. managed the program. "It is wonderful to have completed this landmark experiment testing Einstein's universe. Einstein survives!" said Professor Francis Everitt of Stanford University, principal investigator of Gravity Probe B. "Developing GP-B was a supreme challenge requiring the skillful integration of an extraordinary range of new technologies. -
Moments with Yakov Borisovich Zeldovich
Moments with Yakov Borisovich Zeldovich Remo Ruffini1 ICRANet, p.le della Repubblica, 10 - 65122 Pescara, Italy and ICRA and University of Rome “Sapienza”, p. Aldo Moro 5, I-00185, Rome, Italy and ICRANet, University of Nice-Sophia Antipolis, 28 avenue de Valrose, 06103 Nice Cedex 2, France Abstract. A recollection of special moments spent with Yakov Borisovich Zeldovich and with the scientists of Soviet Union and abroad. The first impression upon meeting a person is the one ing about these methods and commenting appropriately which characterizes all subsequent interactions. also about Sakharov’s recent opinions as presented in the I met Yakov Borisovich Zeldovich for the first time New York Times and asking ourselves about the fate of in 1968 at the GR5 meeting in Tbilisi. I had known Sakharov after his open statements. The plane was sup- his name from his two classic papers on relativistic posed to be a direct flight to Tbilisi of approximately astrophysics in Physics Uspekhi coauthored with Igor seven hours. After approximately three hours of flight, Novikov [1, 2]. There had been a strong impulse to boy- without any announcement, the plane abruptly started to cott the GR5 meeting due to the tense relations over hu- descend quite rapidly and landed in a town called Min- man rights between the Soviet Union and the USA at that eralnye Vody. After landing there was a lot of confu- time. Finally a small group around Johnny Wheeler de- sion, there were additional planes and finally it was dis- cided to participate. Among them were Arthur Komar, closed that, as a common practice in the Soviet Union Bruce Partridge, Abe Taub and myself. -
The Thirteenth Marcel Grossmann Meeting
THE THIRTEENTH MARCEL GROSSMANN MEETING On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories by WSPC on 01/30/15. For personal use only. The Thirteenth Marcel Grossmann Meeting Downloaded from www.worldscientific.com 9194_9789814612180-tpV1.indd 1 3/11/14 12:57 pm July 25, 2013 17:28 WSPC - Proceedings Trim Size: 9.75in x 6.5in icmp12-master This page intentionally left blank by WSPC on 01/30/15. For personal use only. The Thirteenth Marcel Grossmann Meeting Downloaded from www.worldscientific.com PART A THE THIRTEENTH MARCEL GROSSMANN MEETING On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories Proceedings of the MG13 Meeting on General Relativity Stockholm University, Stockholm, Sweden 1–7 July 2012 Editors Robert T Jantzen Villanova University, USA by WSPC on 01/30/15. For personal use only. Kjell Rosquist Stockholm University, Sweden Series Editor The Thirteenth Marcel Grossmann Meeting Downloaded from www.worldscientific.com Remo Ruffini International Center for Relativistic Astrophysics Network (ICRANet), Italy University of Rome “La Sapienza”, Italy World Scientific NEW JERSEY • LONDON • SINGAPORE • BEIJING • SHANGHAI • HONG KONG • TAIPEI • CHENNAI 9194_9789814612180-tpV1.indd 2 3/11/14 12:57 pm Published by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE Library of Congress Cataloging-in-Publication Data Marcel Grossmann Meeting on General Relativity (13th : 2012 : Stockholms universitet) The Thirteenth Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories : proceedings of the MG13 Meeting on General Relativity, Stockholm University, Sweden, 1–7 July 2012 / editors Kjell Rosquist (Stockholm University, Sweden), Robert T. -
MG Awards Booklet
MG12 MARCEL GROSSMANN AWARDS PARIS 2009 ICRA and ICRANet The Institut des Hautes Études Scientifiques is a French institute supporting advanced research in mathematics and theoretical physics. It was created in 1958 by Léon Motchane, an industrialist with a passion for mathematics, with the support of Robert Oppenheimer. It has a small number of permanent professors, appointed for life, and invites about 200 visitors a year for varying terms averaging three months. Over the past decade, 2370 scientists from 60 countries have come to carry out their work at IHÉS. Research is not contracted or directed: it is left to each individual researcher to pursue their own goals. Jean-Pierre Bourguignon is the present Director of IHÉS. 2 12th Marcel Grossmann Meeting July 2009, Paris Institutional Award Institut des Hautes Etudes Scientifique (IHES) for its outstanding contributions to mathematics and theoretical physics, and notably for having renewed basic geometrical concepts, and having developed new mathematical and physical aspects of spacetime. - presented to Prof. Jean-Pierre Bourguignon Individual Awards Jaan Einasto for pioneering contributions in the discovery of dark matter and cosmic web and fostering research in the historical Tartu Observatory. Christine Jones for her fundamental contributions to the X-ray studies of galaxies and clusters tracing their formation and evolution and for her role in collaborations using clusters to study dark matter and in analyzing the effects of outbursts from supermassive black holes on the intracluster gas. Michael Kramer for his fundamental contributions to pulsar astrophysics, and notably for having first confirmed the existence of spin-orbit precession in binary pulsars.