Scientific Background on the Nobel Prize in Physics 2020
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What Geometries Describe Universe Near Big Bang?
Interdisciplinary Studies of Complex Systems No. 9 (2016) 5{24 c Yuri I. Manin Time Between Real and Imaginary: what Geometries Describe Universe near Big Bang? Yuri I. Manin1 Abstract. For about a century, a great challenge for theoretical physics consisted in understanding the role of quantum mode of description of our Universe (\quantum gravity"). Einstein space{times on the scale of ob- servable Universe do not easily submit to any naive quantization scheme. There are better chances to concoct a satisfying quantum picture of the very early space{time, near the Big Bang, where natural scales of events like inflation extrapolated from current observations resist any purely clas- sical description and rather require quantum input. Many physicists and mathematicians tried to understand the quantum early Universe, sometimes unaware of input of the other community. One of the goals of this article is to contribute to the communication of the two communities. In the main text, I present some ideas and results contained in the recent survey/research papers [Le13] (physicists) and [MaMar14], [MaMar15] (mathematicians). Introduction and survey 0.1. Relativistic models of space{time: Minkowski signature. Most modern mathematical models in cosmology start with description of space{time as a 4{dimensional pseudo{Riemannian manifold M endowed with metric 2 X i k ds = gikdx dx of signature (+; ; ; ) where + refers to time{like tangent vectors, whereas the infinitesimal− light{cone− − consists of null{directions. Each such manifold is a point in the infinite{dimensional configuration space of cosmological models. Basic cosmological models are constrained by Einstein equations 1 Rik Rgik + Λgik = 8πGTik − 2 and/or additional symmetry postulates, of which the most essential for us here are the so called Bianchi IX space{times, here with symmetry group SO(3), cf. -
Generation of Angular Momentum in Cold Gravitational Collapse
A&A 585, A139 (2016) Astronomy DOI: 10.1051/0004-6361/201526756 & c ESO 2016 Astrophysics Generation of angular momentum in cold gravitational collapse D. Benhaiem1,M.Joyce2,3, F. Sylos Labini4,1,5, and T. Worrakitpoonpon6 1 Istituto dei Sistemi Complessi Consiglio Nazionale delle Ricerche, via dei Taurini 19, 00185 Rome, Italy e-mail: [email protected] 2 UPMC Univ. Paris 06, UMR 7585, LPNHE, 75005 Paris, France 3 CNRS IN2P3, UMR 7585, LPNHE, 75005 Paris, France 4 Centro Studi e Ricerche Enrico Fermi, Via Panisperna 89 A, Compendio del Viminale, 00184 Rome, Italy 5 INFN Unit Rome 1, Dipartimento di Fisica, Universitá di Roma Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy 6 Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Nonthaburi Campus, 11000 Nonthaburi, Thailand Received 16 June 2015 / Accepted 4 November 2015 ABSTRACT During the violent relaxation of a self-gravitating system, a significant fraction of its mass may be ejected. If the time-varying gravi- tational field also breaks spherical symmetry, this mass can potentially carry angular momentum. Thus, starting initial configurations with zero angular momentum can, in principle, lead to a bound virialised system with non-zero angular momentum. Using numerical simulations we explore here how much angular momentum can be generated in a virialised structure in this way, starting from con- figurations of cold particles that are very close to spherically symmetric. For the initial configurations in which spherical symmetry is broken only by the Poissonian fluctuations associated with the finite particle number N, with N in range 103 to 105, we find that the relaxed structures have standard “spin” parameters λ ∼ 10−3, and decreasing slowly with N. -
Special and General Relativity with Applications to White Dwarfs, Neutron Stars and Black Holes
Norman K. Glendenning Special and General Relativity With Applications to White Dwarfs, Neutron Stars and Black Holes First Edition 42) Springer Contents Preface vii 1 Introduction 1 1.1 Compact Stars 2 1.2 Compact Stars and Relativistic Physics 5 1.3 Compact Stars and Dense-Matter Physics 6 2 Special Relativity 9 2.1 Lorentz Invariance 11 2.1.1 Lorentz transformations 11 2.1.2 Time Dilation 14 2.1.3 Covariant vectors 14 2.1.4 Energy and Momentum 16 2.1.5 Energy-momentum tensor of a perfect fluid 17 2.1.6 Light cone 18 3 General Relativity 19 3.1 Scalars, Vectors, and Tensors in Curvilinear Coordinates 20 3.1.1 Photon in a gravitational field 28 3.1.2 Tidal gravity 29 3.1.3 Curvature of spacetime 30 3.1.4 Energy conservation and curvature 30 3.2 Gravity 32 3.2.1 Einstein's Discovery 32 3.2.2 Particle Motion in an Arbitrary Gravitational Field 32 3.2.3 Mathematical definition of local Lorentz frames . 35 3.2.4 Geodesics 36 3.2.5 Comparison with Newton's gravity 38 3.3 Covariance 39 3.3.1 Principle of general covariance 39 3.3.2 Covariant differentiation 40 3.3.3 Geodesic equation from covariance principle 41 3.3.4 Covariant divergente and conserved quantities . 42 3.4 Riemann Curvature Tensor 45 x Contents 3.4.1 Second covariant derivative of scalars and vectors 45 3.4.2 Symmetries of the Riemann tensor 46 3.4.3 Test for flatness 47 3.4.4 Second covariant derivative of tensors 47 3.4.5 Bianchi identities 48 3.4.6 Einstein tensor 48 3.5 Einstein's Field Equations 50 3.6 Relativistic Stars 52 3.6.1 Metric in static isotropic spacetime 53 -
Stephen Hawking (1942–2018) World-Renowned Physicist Who Defied the Odds
COMMENT OBITUARY Stephen Hawking (1942–2018) World-renowned physicist who defied the odds. hen Stephen Hawking was speech synthesizer processed his words and diagnosed with motor-neuron generated the androidal accent that became disease at the age of 21, it wasn’t his trademark. In this way, he completed his Wclear that he would finish his PhD. Against best-selling book A Brief History of Time all expectations, he lived on for 55 years, (Bantam, 1988), which propelled him to becoming one of the world’s most celebrated celebrity status. IAN BERRY/MAGNUM scientists. Had Hawking achieved equal distinction Hawking, who died on 14 March 2018, was in any other branch of science besides cos- born in Oxford, UK, in 1942 to a medical- mology, it probably would not have had the researcher father and a philosophy-graduate same resonance with a worldwide public. As mother. After attending St Albans School I put it in The Telegraph newspaper in 2007, near London, he earned a first-class degree “the concept of an imprisoned mind roaming in physics from the University of Oxford. He the cosmos” grabbed people’s imagination. began his research career in 1962, enrolling In 1965, Stephen married Jane Wilde. as a graduate student in a group at the Uni- After 25 years of marriage, and three versity of Cambridge led by one of the fathers children, the strain of Stephen’s illness of modern cosmology, Dennis Sciama. and of sharing their home with a team of The general theory of relativity was at that nurses became too much and they sepa- time undergoing a renaissance, initiated in rated, divorcing in 1995. -
Exploring the Galactic Center
Exploring the V Galactic Center Goinyk/Shutterstock.com olodymyr A case study of how USRA answered a question posed by James Webb in 1966. On 14 January 1966, NASA (5) C r e Administrator James Webb (1906-1992) wrote a letter d i Should we change the t : N to the prominent Harvard physicist, Professor Norman A orientation of some of S F. Ramsey Jr. (1915-2011), asking him to establish an A our NASA Centers? advisory group that would: (6) What steps should Review the resources at our NASA field centers, and James Webb be taken in scientific such other institutions as would be appropriate, staffing, both inside and against the requirements of the next generation of outside NASA, over the next few years to assure that space projects and advise NASA on a number of key we have the proper people at the proper places to do problems, such as: the job? (1) How can we organize these major projects so that (7) How can we obtain the competent scientists to the most competent scientists and engineers can take the key roles in these major projects? 1 participate? Ramsey assembled his advisory group, and they (2) How can academic personnel participate and at worked through the spring and summer on their report, the same time continue in strong academic roles? which they delivered to the Administrator on 15 August 1966. Their first recommendation was that the NASA (3) What mechanism should be used to determine Administrator appoint a General Advisory Committee the scientific investigations which should be to bring to bear “maximum competence” on “the conducted? formulation and execution of long-term programs of NASA.”2 (4) How does a scientist continue his career development during the six to eight years it requires This recommendation, and many of the others in the to develop an ABL [Automated Biological Laboratory] report, were not what NASA was looking for, and so or a large astronomical facility? the Administrator turned to the National Academy of Sciences to find answers for at least some of the Infrared radiation gets Cr ed i t: A questions posed to Ramsey. -
Newton's Aether Model
Newton’s aether model Eric Baird ([email protected]) Isaac Newton is usually associated with the idea of absolute space and time, and with ballistic light-corpuscle arguments. However, Newton was also a proponent of wave/particle duality, and published a “new” variable-density aether model in which light and matter trajectories were either bent by gravitational fields, or deflected by an aether density gradient. Newton’s (flawed) aether model can be considered as an early attempt at a curved-space model of gravity. 1. Introduction In “Opticks”, Newton’s idealised absolute space Modern textbooks typically say that Newton is occupied by a “new” form of medium whose believed that space and time were absolute and density depends on gravitational properties, inviolable. However, a reading of Newton’s with variations in aether density producing the “Principia” [1] and “Opticks” [2] reveals a effects that would otherwise be described as the rather different picture, with Optiks in results of a gravitational field. The resulting particular documenting Newton’s attempt to metric associates a gravitational field with produce a model of gravity in which a signal flight-time differences (see: Shapiro gravitational field could be represented as a effect) that deflect light, leading to a normalised series of light-distance differentials, or as a lightbeam-geometry that is not Euclidean. Since variation in lightspeed or refractive index. This these effects are described in modern theory as can be compared to Einstein’s “refractive” the effects of curved space, it seems reasonable approach to gravitational light-bending in 1911 to interpret Newton’s “absolute space” as an ( [3] §4 ) and to his description of general absolute Euclidean embedding-space that acts relativity as a (nonparticulate!) gravitational as a container for non-Euclidean geometry, aether model in 1920 [4][5]. -
Weighing the World the Reverend John Michell of Thornhill
66 Human Sciences Springer News 7/2011 springer.com/NEWSonline R. McCormmach, Eugene, OR, USA (Ed.) Weighing the World The Reverend John Michell of Thornhill The book about John Michell (1724-93) has two parts. The first and longest part is biographical, an account of Michell’s home setting (Notting- hamshire in England), the clerical world in which he grew up (Church of England), the university (Cambridge) where he studied and taught, and the scientific activities he made the center of his life. The second part is a complete edition of his known letters. Half of his letters have not been previously published; the other half are brought together in one place for the first time. The letters touch on all aspects of his career, and because they are in his words, they help bring the subject to life. His publi- cations were not many, a slim book on magnets and magnetism, one paper on geology, two papers on astronomy, and a few brief papers on other topics, but they were enough to leave a mark on several sciences. He has been called a geologist, an astronomer, and a physicist, which he was, though we best remember him as a natural philosopher, as one who investigated physical nature broadly. His scientific contribution is not easy to summa- rize. Arguably he had the broadest competence of any British natural philosopher of the eighteenth century: equally skilled in experiment and obser- vation, mathematical theory, and instruments, his field of inquiry was the universe. From the structure of the heavens through the structure of the Earth to the forces of the elementary particles of matter, he carried out original and far-reaching researches on the workings of nature. -
Review Study on “The Black Hole”
IJIRST –International Journal for Innovative Research in Science & Technology| Volume 2 | Issue 10 | March 2016 ISSN (online): 2349-6010 Review Study on “The Black Hole” Syed G. Ibrahim Department of Engineering Physics (Nanostructured Thin Film Materials Laboratory) Prof. Ram Meghe College of Engineering and Management, Badnera 444701, Maharashtra, India Abstract As a star grows old, swells, then collapses on itself, often you will hear the word “black hole” thrown around. The black hole is a gravitationally collapsed mass, from which no light, matter, or signal of any kind can escape. These exotic objects have captured our imagination ever since they were predicted by Einstein's Theory of General Relativity in 1915. So what exactly is a black hole? A black hole is what remains when a massive star dies. Not every star will become a black hole, only a select few with extremely large masses. In order to have the ability to become a black hole, a star will have to have about 20 times the mass of our Sun. No known process currently active in the universe can form black holes of less than stellar mass. This is because all present black hole formation is through gravitational collapse, and the smallest mass which can collapse to form a black hole produces a hole approximately 1.5-3.0 times the mass of the sun .Smaller masses collapse to form white dwarf stars or neutron stars. Keywords: Escape Velocity, Horizon, Schwarzschild Radius, Black Hole _______________________________________________________________________________________________________ I. INTRODUCTION Soon after Albert Einstein formulated theory of relativity, it was realized that his equations have solutions in closed form. -
Nearby Dwarf Galaxies and Imbh Mini-Spikes
SF2A 2008 C. Charbonnel, F. Combes and R. Samadi (eds) DARK MATTER SEARCHES WITH H.E.S.S: NEARBY DWARF GALAXIES AND IMBH MINI-SPIKES Moulin, E.1, Vivier, M. 1 , Brun, P.1 , Glicenstein, J-F.1 and the H.E.S.S. Collaboration2 Abstract. WIMP pair annihilations produce high energy gamma-rays, which can be detected by IACTs such as the H.E.S.S. array of Imaging Atmospheric Cherenkov telescopes. Nearby dwarf galaxies and mini- spikes around intermediate-mass black holes (IMBHs) in the Galactic halo are possible targets for the ob- servation of these annihilations. H.E.S.S. observations on the nearby dwarf galaxy candidate Canis Major is reported. Using a modelling of the unknown dark matter density profile, constraints on the velocity-weighted annihilation cross section of DM particles are derived in the framework of Supersymmetric (pMSSM) and Kaluza-Klein (KK) models. Next, a search for DM mini-spikes around IMBHs is described and constraints on the particle physics parameters in various scenarios are given. 1 Introduction WIMPS (Weakly Interacting Massive Particles) are among the best motivated particle dark matter candidates. The WIMP annihilation rate is proportional to the square of the DM density integrated along the line of sight. Celestial objects with enhanced DM density are thus primary targets for indirect DM searches. Among these are the Galactic Center, nearby external galaxies and substructures in galactic haloes. In this paper, we report on H.E.S.S. results towards a dwarf galaxy candidate, Canis Major, and on a search for DM mini-spikes around IMBHs. -
New APS CEO: Jonathan Bagger APS Sends Letter to Biden Transition
Penrose’s Connecting students A year of Back Page: 02│ black hole proof 03│ and industry 04│ successful advocacy 08│ Bias in letters of recommendation January 2021 • Vol. 30, No. 1 aps.org/apsnews A PUBLICATION OF THE AMERICAN PHYSICAL SOCIETY GOVERNMENT AFFAIRS GOVERNANCE APS Sends Letter to Biden Transition Team Outlining New APS CEO: Jonathan Bagger Science Policy Priorities BY JONATHAN BAGGER BY TAWANDA W. JOHNSON Editor's note: In December, incoming APS CEO Jonathan Bagger met with PS has sent a letter to APS staff to introduce himself and President-elect Joe Biden’s answer questions. We asked him transition team, requesting A to prepare an edited version of his that he consider policy recom- introductory remarks for the entire mendations across six issue areas membership of APS. while calling for his administra- tion to “set a bold path to return the United States to its position t goes almost without saying of global leadership in science, that I am both excited and technology, and innovation.” I honored to be joining the Authored in December American Physical Society as its next CEO. I look forward to building by then-APS President Phil Jonathan Bagger Bucksbaum, the letter urges Biden matically improve the current state • Stimulus Support for Scientific on the many accomplishments of to consider recommendations in the of America’s scientific enterprise Community: Provide supple- my predecessor, Kate Kirby. But following areas: COVID-19 stimulus and put us on a trajectory to emerge mental funding of at least $26 before I speak about APS, I should back on track. -
Thunderkat: the Meerkat Large Survey Project for Image-Plane Radio Transients
ThunderKAT: The MeerKAT Large Survey Project for Image-Plane Radio Transients Rob Fender1;2∗, Patrick Woudt2∗ E-mail: [email protected], [email protected] Richard Armstrong1;2, Paul Groot3, Vanessa McBride2;4, James Miller-Jones5, Kunal Mooley1, Ben Stappers6, Ralph Wijers7 Michael Bietenholz8;9, Sarah Blyth2, Markus Bottcher10, David Buckley4;11, Phil Charles1;12, Laura Chomiuk13, Deanne Coppejans14, Stéphane Corbel15;16, Mickael Coriat17, Frederic Daigne18, Erwin de Blok2, Heino Falcke3, Julien Girard15, Ian Heywood19, Assaf Horesh20, Jasper Horrell21, Peter Jonker3;22, Tana Joseph4, Atish Kamble23, Christian Knigge12, Elmar Körding3, Marissa Kotze4, Chryssa Kouveliotou24, Christine Lynch25, Tom Maccarone26, Pieter Meintjes27, Simone Migliari28, Tara Murphy25, Takahiro Nagayama29, Gijs Nelemans3, George Nicholson8, Tim O’Brien6, Alida Oodendaal27, Nadeem Oozeer21, Julian Osborne30, Miguel Perez-Torres31, Simon Ratcliffe21, Valerio Ribeiro32, Evert Rol6, Anthony Rushton1, Anna Scaife6, Matthew Schurch2, Greg Sivakoff33, Tim Staley1, Danny Steeghs34, Ian Stewart35, John Swinbank36, Kurt van der Heyden2, Alexander van der Horst24, Brian van Soelen27, Susanna Vergani37, Brian Warner2, Klaas Wiersema30 1 Astrophysics, Department of Physics, University of Oxford, UK 2 Department of Astronomy, University of Cape Town, South Africa 3 Department of Astrophysics, Radboud University, Nijmegen, the Netherlands 4 South African Astronomical Observatory, Cape Town, South Africa 5 ICRAR, Curtin University, Perth, Australia 6 University -
Aleksei A. Abrikosov 1928–2017
Aleksei A. Abrikosov 1928–2017 A Biographical Memoir by M. R. Norman ©2018 National Academy of Sciences. Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences. ALEKSEI ALEKSEEVICH ABRIKOSOV June 25, 1928–March 29, 2017 Elected to the NAS, 2000 Shortly after the 2003 announcement that Aleksei Abrikosov had won the Nobel Prize in Physics, a number of colleagues took Alex to lunch at a nearby Italian restau- rant. During lunch, one of the Russian visitors exclaimed that Alex should get a second Nobel Prize, this time in Literature for his famous “AGD” book with Lev Gor’kov and Igor Dzyaloshinskii (Methods of Quantum Field Theory in Statistical Physics.) Somewhat taken aback, I looked closely at this individual and realized that he was deadly serious. Although I could imagine the reaction of the Nobel Literature committee to such a book (for a lay person, perhaps analogous to trying to read Finnegan’s Wake), I had to admit that my own copy of this book is quite dog-eared, having been put to good use over the By M. R. Norman years. In fact, you know you have made it in physics when your book gets a Dover edition. One of the most charming pictures I ever saw was a rare drawing in color that Alexei Tsvelik did (commissioned by Andrei Varlamov for Alex’s 50th birthday) that was proudly displayed in Alex’s home in Lemont, IL. It showed Alex with his fingers raised in a curled fashion as in the habit of medieval Popes.