DOCSLIB.ORG

Physics News

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physics News SCHOOL OF PHYSICS Physics News FACULTY OF SCIENCE SPRING 2012 Most of the Experimental Particle Physics group at the School of Physics, led by Associate Professor Kevin Varvell, travelled to Melbourne HIGGS-LIKE BOSON for the ICHEP Conference. The group is actively involved in the world- wide effort to exploit the huge amount of data flowing from the LHC, as DISCOVERY MARKS part of the ATLAS experiment. Together with the emerging theoretical particle physics group it forms the Sydney node of the ARC Centre of Excellence for Particle Physics at the Terascale (CoEPP), an alliance of THE BEGINNING four leading Australian universities, which focusses research activities OF A NEW ERA on some of the most fundamental questions of contemporary physics. What is so special about the Higgs particle? The properties of elementary particles such as quarks and leptons and force-carrier IN PARTICLE PHYSICS vector bosons (photons, gluons and the weakly interacting W and Z) are essentially determined by two fundamental physical theories: BY ARCHIL KOBAKHIDZE special relativity and quantum mechanics. When these two theories are combined together, we are lead to a model, known as the Standard On July 4, during a joint seminar at CERN (the European Organization Model, which consistently describes all currently known phenomena for Nuclear Research) in Geneva, two major experiments at the Large in the micro-world. The only caveat of the Standard Model is that, in Hadron Collider (LHC), ATLAS and CMS, reported the discovery of order to account for the observed masses of elementary particles, we a new particle, 134 times heavier than the proton. The seminar was must introduce a classical field, which is constant throughout space and live streamed as a curtain raiser to the year’s major particle physics time. This field, known as the “Higgs vacuum field” acts as a medium conference, ICHEP2012 in Melbourne, and viewed by thousands of for some elementary particles (quarks, leptons and W/Z), while being physicists and non-experts around the globe. This seminar is likely completely transparent for others (photons, gluons). When particles to become a historic event, because the discovered particle closely propagate in the “Higgs medium” they effectively slow down and are, resembles the long-awaited Higgs boson. therefore, seen as having masses (inertia). Image of two electrons and two muons CONTINUES PAGE 2 HIGGS-LIKE BOSON DISCOVERY MARKS THE BEGINNING OF A NEW ERA IN PARTICLE PHYSICS CONTINUED FROM PAGE 1 HEADLINE Quantum mechanics generically implies that such a classical TIM BEDDING Higgs field must be accompanied by quantum excitations, which are nothing but Higgs particles. This was first realised by British I am delighted and honoured to take over as Head of the School theoretical physicist Peter Higgs in 1964, and independently by of Physics. The School is going through some major changes, with Robert Brout and Francois Englert, and Gerald Guralnik, C.R. Hagen quite a few staff coming and going, and with the exciting challenge and Tom Kibble. It took a long 48 years and a tremendous effort by of the new building that will be growing in front of our eyes over generations of physicists from around the world to get from the the next two years. Amidst these changes, the activities of the theoretical prediction of the Higgs boson to its apparent discovery. School in teaching and research are carrying on with greater strength The world without the Higgs field would look very different from than ever. the one we live in. In the hypothetical Higgsless world the proton The excellence of our research has never been more evident, as the would have been heavier than the neutron. As a result, chemical stories in this and other recent issues of Physics News can attest. compounds would have been entirely different. A different proton- Last year, the School of Physics produced more research publications to-neutron mass ratio would also affect the production of primordial than any other School in the Faculty of Science (and more than elements in the course of evolution of the Universe, which in turn quite a few faculties). This is a truly outstanding result. Of course, would dramatically change the creation and evolution of largescale the number of publications is only one measure, and we should structures, i.e. stars and galaxies. Actually it doesn’t end there - in also boast about our success in gaining competitive grants, hosting the Higgless world the electron would have been massless and there Centres of Excellence and winning fellowships. On the latter score, would not even be ordinary atoms. The importance of the Higgs it is a great pleasure to congratulate three new winners: Marcela boson in shaping our Universe and, ultimately, our own existence Bilek and Bruce Yabsley have been awarded ARC Future Fellowships, is fully reflected in its popular if controversial nickname, the “God and Ben Eggleton was named as ARC Australian Laureate Fellow. Particle”. At the recent University Open Day, where scores of high-school students were keen to hear about physics, it was great to be able to tell them that our physicists are working at the cutting edge over a whole range of topics, from the discovery of the Higgs boson and the observation of the distant universe, to the developments of nanoscale optics and quantum computers. Our teaching also goes from strength to strength, and our student numbers remain high at all levels. At a recent meeting with student representatives, where we solicit feedback on all aspects of our teaching, it was wonderful to hear them volunteer that Physics is one of the strongest teaching departments. To quote one student, ‘I think physics has some of the best teaching staff I have seen anywhere’. Good teaching does not just happen, it takes a lot of hard work and commitment from a whole range of people: lecturers and tutors, as well as technical and administrative staff. With such a terrific group of people working together in the pursuit of excellence (to borrow Harry Messel’s famous catch cry), both in Physics student Curtis Black, presenting his poster at the ICHEP teaching and research, I have a feeling that my new job is going to conference. Credit: Laura Vanags. be a lot of fun. I look forward to it immensely. Largely because of its supposed universal role in generating masses for all the other fundamental particles, the Higgs boson is rather hard to detect. Once produced in high energy collisions of protons, it decays very quickly, long before we have a chance to photograph Tim Bedding it. Scientists can’t catch the Higgs boson directly, but they can Head, School of Physics detect some of the particles the Higgs boson decays into. Different product particles manifest themselves differently in the detector. By looking at which particles are detected, and tracing them back, one can infer that a Higgs boson was created in the detector. This is an incredibly complicated process, because each second about a billion collisions happen at the LHC and many particles produced in those collisions behave similarly to the products of the Higgs boson decay. The discovery of a Higgs-like particle marks the beginning of a new era in particle physics. It is yet to be confirmed that the discovered particle is indeed the Higgs boson of the Standard Model, or a particle from a more involved theory. This requires more diligent study of its properties, such as its spin, and interactions with other particles, which can be established by collecting more experimental data. Moreover, theoretical considerations suggest that the Higgs boson is likely to be accompanied by other particles, which are expected to be discovered at the LHC in future. 2 PHYSICS NEWS SPRING 2012 INSTITUTE OF MEDICAL PHYSICS LEADS NATIONAL INITIATIVE IN TEACHING AND RESEARCH BY DAVID THWAITES The Institute of Medical Physics (IMP) was founded in the School of Physics by Clive Baldock some years ago and recently developed further by David Thwaites, both having held the post of Professor of Medical Physics in an on-going research agreement with the NSW Health Dept (now the NSW Ministry of Health). The IMP has been successful in attracting grants from the Department of Health and Aging (DoHA) to develop Examples of radiation dose distributions for a nasopharyx treatment, on a national framework for both patient CT scan images; red is higher dose, blue is lower. On the left are education and research in medical dynamically-delivered intensity-modulated x-ray treatments; on the right, physics. This is aimed at developing distributions using proton beam treatment (courtesy, Tony Lomax, PSI, Villigen, the infrastructure and capacity of Switzerland, within a PSI-Leeds,UK-IMP,Sydney collaboration) the joint university-hospital medical physics education and training system; to teach masters students, to universities of hospital-based education and a new inter-linked web- supervise and support post-graduate students, to support and develop based information platform for use by students, clinical medical physics collaborative research programs and to increase the links between trainees and practicing medical physicists. In research, it involves setting academic and clinical medical physics groups. up conjoint research appointments between universities and partner hospitals to support translational research in high-technology based In its widest sense, Medical Physics is the application of physics radiation oncology imaging and treatment methods. The posts will be at principles, methods and techniques to any area of medicine. In clinical both post-doctoral level and visiting overseas scholar/researcher levels. practice, the major speciality areas employing physicists are in radiation oncology, medical imaging of all types and nuclear medicine. However, The successful DoHA grants have leveraged further linkage-type research areas in medical physics span a wide spectrum from basic matching funding from universities and then from partner hospitals’ own science at the molecular and cellular level up to translational research research and endowment funds, to significantly increase the resource in partnership with medical specialists at the interface with clinical for the initiative.
Load more

Recommended publications
  • The Large Numbers Hypothesis: Outline of a Self-Similar Quantum
    The Large Numbers Hypothesis: Outline of a self-similar quantum-cosmological Model H. GENREITH ∗ Institut f¨ur Geophysik und Meteorologie der Universit¨at zu K¨oln Abstract leads to a scaled quantum of action 3 In 1919 A. Einstein suspected first that gravita- H =Λ h (2) · tional fields could play an essential role in the in order to handle the Universe like an elementary structure of elementary particles. In 1937, P.A.M. particle. Hence the Universe should have an angu- Dirac found a miraculous link between the prop- lar momentum of about H/2π and it can be sus- erties of the visible Universe and elementary par- pected to be a huge rotating black-hole close to its ticles. Both conjectures stayed alive through the Kerr limit, or close to G¨odel’s spin [1, 2, 35, 10], following decades but still no final theory could be which is the value for the rotating cosmological so- derived to this issues. The herein suggested frac- lution to Einstein’s equations of General Relativity. tal model of the Universe gives a consistent expla- The recent discussion regarding the origin of and nation to Dirac’s Large Numbers Hypothesis and destiny of the Universe raises, for example, the combines the conjectures of Einstein and Dirac. question of where the Universe comes from. The main explanation for this is that time and space 1 Introduction were created with the big-bang and therefore the question of where the Universe is embedded or what 1.1 The Large Numbers Hypothesis happened before the creation, is not admissible.
    [Show full text]
  • What Is Gravity and How Is Embedded in Mater Particles Giving Them Mass (Not the Higgs Field)? Stefan Mehedinteanu
    What Is Gravity and How Is Embedded in Mater Particles giving them mass (not the Higgs field)? Stefan Mehedinteanu To cite this version: Stefan Mehedinteanu. What Is Gravity and How Is Embedded in Mater Particles giving them mass (not the Higgs field)?. 2017. hal-01316929v6 HAL Id: hal-01316929 https://hal.archives-ouvertes.fr/hal-01316929v6 Preprint submitted on 23 Feb 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution| 4.0 International License What Is Gravity (Graviton) and How Is Embedded in Mater Particles Giving Them Mass (Not the Higgs Field)? Stefan Mehedinteanu1 1 (retired) Senior Researcher CITON-Romania; E-Mail: [email protected]; [email protected] “When Einstein was asked bout the discovery of new particles, the answer it was: firstly to clarify what is with the electron!” Abstract It will be shown how the Micro-black-holes particles produced at the horizon entry into a number of N 106162 by quantum fluctuation as virtual micro-black holes pairs like e+ e- creation, stay at the base of: the origin and evolution of Universe, the Black Holes (BH) nuclei of galaxies, of the free photons creation of near mass-less as by radiation decay that condensate later at Confinement in to the structure of gauge bosons (gluons) .
    [Show full text]
  • Cosmological Matter-Antimatter Asymmetry and Antimatter in the Universe
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server COSMOLOGICAL MATTER-ANTIMATTER ASYMMETRY AND ANTIMATTER IN THE UNIVERSE A.D. DOLGOV INFN, sezione di Ferrara, Via Paradiso, 12 - 44100 Ferrara, Italy and ITEP, Bol. Cheremushkinskaya 25, Moscow 113259, Russia Models of baryogenesis which may lead to astronomically significant amount of antimatter in the universe are reviewed. Observational features are briefly discussed. 1 Introduction Prediction of antimatter by Dirac 1 (1928) and quick subsequent discovery of the first antimatter particle, positron, by Anderson 2 (1933) are among greatest scientific achievements of XX cen- tury. Discovery of antiproton 22 years later 3 was the next step which had opened a whole new world of antiparticles. Now for (almost) every elementary particle a corresponding antiparticle has also been observed. The latter have opposite signs of all associated charges and, according to CPT theorem4, the same masses and, if unstable, life-times. Such symmetry between par- ticles and antiparticles naturally leads to suggestion that the universe as a whole may be also symmetric with respect to transformation from particles to antiparticles and there should exist astronomically large regions consisting of antimatter: anti-stars, clouds of diffuse antimatter, whole anti-galaxies, or even large clusters of anti-galaxies. As Dirac 5 said in his Nobel lecture a: “... we must regard it rather as an accident that the Earth (and presumably the whole solar system), contains a preponderance of negative electrons and positive protons. It is quite possible that for some of the stars it is the other way about, these stars being built up mainly of positrons and negative protons.
    [Show full text]
  • Curriculum Vitae: M. Coleman Miller Date of Birth
    Curriculum Vitae: M. Coleman Miller Date of Birth: 6 July 1968 The University of Maryland Place of Birth: Detroit, MI Department of Astronomy Citizenship: USA College Park, MD 20742-2421 E-mail: [email protected] Telephone: (301) 405-1037 FAX: (301) 314-9067 Webpage: http://www.astro.umd.edu/∼miller/ Research Interests Theoretical Astrophysics Computer Simulations and Modeling Physics of Dense Matter Physics in Strong Magnetic Fields General Relativity Gravitational Radiation PlasmaPhysics GravitationalLensing Education 1984 - 1990 California Institute of Technology, Pasadena, California Department: Physics, with Computer Science minor Thesis Topic: Radiation Transfer in Very Strong Magnetic Fields Degrees: M.S. (1986), Ph.D. (1990) (Advisor: E. S. Phinney) National Science Foundation Graduate Fellow, 1984-1987 1980 - 1984 Hillsdale College, Hillsdale, Michigan Major fields: Mathematics and Physics Degree: B.S., Summa Cum Laude (1984) Research Experience 2009 - Professor of Astronomy, University of Maryland 2020 Radboud Excellence Professor, Radboud University, Nijmegen, Netherlands 2017 - 2019 Chair, Maryland Astronomy Center for Theory and Computation 2015 - 2019 Astronomy Director, Joint Space-Science Institute 2013 - 2014 Director, Joint Space-Science Institute 2004 - 2009 Associate Professor of Astronomy, University of Maryland 2004 - 2006 Chair, Maryland Astronomy Center for Theory and Computation 1999 - 2004 Assistant Professor of Astronomy, University of Maryland 1997 - 1999 Member of the AXAF Science Center, Chicago beta test site 1994 - 1997 Compton Gamma-Ray Observatory Fellow, University of Chicago 1993 - 1999 Research Scientist, University of Chicago Constructed the first detailed model of kilohertz QPOs of neutron star low-mass X- ray binaries, investigated gravitational lensing of gamma-ray bursts and galaxies, and performed various studies of accreting black holes and neutron stars.
    [Show full text]
  • Grand Unified Theories - Ii
    - 31 - GRAND UNIFIED THEORIES - II J. Ellis CERN, Geneva, Switzerland INTRODUCTION In the previous lectures1»2) you have seen how the inadequacies of the standard SU(3) x SU(2) x U(l) model of the strong, weak, and electromagnetic interactions motivate the construction of grand unified theories (GUTs) which are sketched in Fig. 1. The strategy- then adopted was to assign the fundamental fermions — quarks and leptons — to "generations" forming economical representations of a simple grand unifying group G. The observed dis• parity of the strong and weak coupling constants implies that the group G must be broken down at a very high energy scale. The properties of the running coupling constants in re- normalizable field theories enable one to estimate3) this breaking scale to be around 1015 GeV in simple models'*) such as SU(5). Although the grand unification symmetry is very strongly broken, it can still be used to make predictions for parameters observable at low energies. In addition to the quantization of electromagnetic charge (|Q_|/|Q | = 1) which ^e p flows from the embedding of electromagnetic U(l) into a simple group, it is possible to 2 make predictions for the neutral weak mixing parameter sin 6W and for the ratios of certain 2 quark and lepton masses. While the predictions for sin 9W and m^/m^. are spectacularly successful, there are clouds over the predictions for the masses of other quarks1»2). The real tests of GUTs lie, however, with their predictions for new interactions, which can lead to qualitatively new phenomena such as baryon decay or neutrino masses and oscilla• tions.
    [Show full text]
  • Black Hole Entropy Entanglement And
    BLACK HOLE ENTROPY ! ENTANGLEMENT! AND! HOLOGRAPHIC SPACETIME" Ted Jacobson" University of Maryland" Goddard Scientific Colloquium, Feb. 7, 2018 Holographic " Information" principle" paradox" Area 3 4~GN /c geometry" black hole " Einstein eqn " from" entropy" as vacuum " entanglement " thermodynamics" QFT " renormalization" Albert Einstein, aged 33, 1912" GRAVITY IS CURVATURE OF SPACETIME" Spatial curvature analogy:" " Spacetime" Initially parallel lines " don’t stay parallel" time" earth" apple" Time runs slower lower down!" B" Apple free-fall " apple" is the straightest path " in spacetime between A & B…" and the path of longest time." How much slower? " One billionth of a second per year per foot" A" ’ 2 earth" at the earth s surface (g/c )." Spiral of Mercury’s orbit: didn’t fit Newton’s theory, " by 43’’/century…" That’s about 9 minutes advance time for the transit per century… " General relativity nailed it." To calculate the rate of perihelion advance Einstein needed only the first approximation to the line element outside the sun: " " 2 2 2 2 2 2 2 ds = (1− rS r)dt − (1+ rS r)dr − r (dθ +sin θ dϕ ) 2 rS = 2GM c = 3km The Schwarzschild Singularity (1916) 2 2 −1 2 2 2 2 2 ds = (1− rS r)dt − (1− rS r) dr − r (dθ +sin θ dϕ ) 2 rS = 2GM c = 3km "Schwarzschild radius" Schwarzschild (1916): “in order that this discontinuity coincides with the origin” one should define the radial coordinate appropriately. Droste (1916): “a moving particle can never pass that sphere because it would take an infinite amount of time” The true, non-singular nature of the Schwarzschild “singularity” was not widely understood until 42 years later… but it was understood perfectly well by one man in 1932… Georges Lemaitre First person to understand the nature of the Schwarzschild singularity as an event horizon (1932).
    [Show full text]
  • Neutrino Decoherence from Quantum Gravitational Stochastic Perturbations
    Neutrino decoherence from quantum gravitational stochastic perturbations Stuttard, Thomas; Jensen, Mikkel Published in: Physical Review D DOI: 10.1103/PhysRevD.102.115003 Publication date: 2020 Document version Publisher's PDF, also known as Version of record Document license: CC BY Citation for published version (APA): Stuttard, T., & Jensen, M. (2020). Neutrino decoherence from quantum gravitational stochastic perturbations. Physical Review D, 102(11), [115003]. https://doi.org/10.1103/PhysRevD.102.115003 Download date: 30. sep.. 2021 PHYSICAL REVIEW D 102, 115003 (2020) Neutrino decoherence from quantum gravitational stochastic perturbations Thomas Stuttard and Mikkel Jensen Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark (Received 9 July 2020; accepted 30 October 2020; published 1 December 2020) Neutrinos undergoing stochastic perturbations as they propagate experience decoherence, damping neutrino oscillations over distance. Such perturbations may result from fluctuations in space-time itself if gravity is a quantum force, including interactions between neutrinos and virtual black holes. In this work we model the influence of heuristic neutrino-virtual black hole interaction scenarios on neutrino propagation and evaluate the resulting signals in astrophysical and atmospheric neutrinos. We derive decoherence operators representing these effects in the framework of open quantum systems, allowing experimental constraints on such systems to be connected to quantum gravitational effects. Finally, we consider
    [Show full text]
  • Arxiv:1805.01467V1 [Astro-Ph.GA] 3 May 2018 the Existence of Stellar Mass Black Holes (Abbott Et Al
    Draft version May 7, 2018 Typeset using LATEX twocolumn style in AASTeX62 A Population of Bona Fide Intermediate Mass Black Holes Identified as Low Luminosity Active Galactic Nuclei Igor V. Chilingarian,1, 2 Ivan Yu. Katkov,2 Ivan Yu. Zolotukhin,2, 3, 4 Kirill A. Grishin,2, 5 Yuri Beletsky,6 Konstantina Boutsia,6 and David J. Osip6 1Smithsonian Astrophysical Observatory, 60 Garden St. MS09, Cambridge, MA 02138, USA 2Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, Universitetsky prospect 13, Moscow, 119992, Russia 3Special Astrophysical Observatory of the Russian Academy of Sciences, Nizhnij Arkhyz 369167, Russia 4Universit´ede Toulouse; UPS-OMP, IRAP, 9 avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France 5Department of Physics, M.V. Lomonosov Moscow State University, 1 Vorobyovy Gory, Moscow, 119991, Russia 6Las Campanas Observatory, Carnegie Institution of Washington, Colina el Pino, Casilla 601 La Serena, Chile (Received April 26, 2018; Revised {; Accepted {) Submitted to ApJ ABSTRACT Nearly every massive galaxy harbors a supermassive black hole (SMBH) in its nucleus. SMBH masses are millions to billions M , and they correlate with properties of spheroids of their host galaxies. While the SMBH growth channels, mergers and gas accretion, are well established, their origin remains 5 6 uncertain: they could have either emerged from massive \seeds" (10 10 M ) formed by direct − collapse of gas clouds in the early Universe or from smaller (100M ) black holes, end-products of first stars. The latter channel would leave behind numerous intermediate mass black holes (IMBHs, 2 5 10 10 M ). Although many IMBH candidates have been identified, none is accepted as definitive, − thus their very existence is still debated.
    [Show full text]
  • The Virtual Black Hole in 2D Quantum Gravity Search for the Quark-Gluon
    Der neutrale Kei Zerfall ist experimentell wesentlich weniger genau untersucht als der entsprechende K± Zerfall (bei letzterem wurden bisher einige zehntausend Er- eignisse beobachtet, bei ersterem nicht einmal tausend). Allerdings hat er einige interessante physikalische Eigenschaften: aus Symmetriegründen ist der ansonsten dominierende Formfaktor F stark unterdrückt, wodurch sich die Pionen in einem (fast) reinem p-Zustand befinden, während beim K*t Zerfall ein Mischzustand vorliegt. Weiters stellt sich im Rahmen chiraler Störungstheorie eine empfindli- che Abhängigkeit des Verzweigungsverhältnisses von dem nur ungenau bekannten Kopplungsparameter L3 heraus, was den neutralen Ket Zerfall zur Messung dieses Parameters prädestiniert. Der Vortrag berichtet über theoretische Untersuchungen sowie erste experimentel- le Ergebnisse der Kti Analyse. Da das im Mai veröffentlichte neue Ergebnis der Re^/e) Messung eine grosse Resonanz gefunden hat, wird auch dieses kommen- tiert werden. •) Gefördert aus Mitteln des BMWV: GZ 616.360/2-W und GZ 616.363/2-VIII, sowie des Fonds zur Förderung der wissenschaftlichen Forschung: P-8929-PHY. The Virtual Black Hole in 2D Quantum Gravity D. Grumiller1, W. Kummer1, D.V. Vassilevich2, i 'Institut für Theoretische Physik, TU Wien, Wiedner Hauptstrasse 8-10, j A-1040 Wien; 2Institut für Theoretische Physik, Universität Leipzig, Augu- j stusplatz 10, D-04109 Leipzig > As shown recently 2d quantum gravity theories — including spherically reduced ~H Einstein-gravity — after an exact path integral of its geometric part can be treated ^ perturbatively in the loops of (scalar) matter. Obviously the classical mechanism of O black hole formation should be contained in the tree approximation of the theory. ~ This is shown to be the case for the scattering of two scalars through an interme- —L diate state which by its effective black hole mass is identified as a "Virtual black •£* hole".
    [Show full text]
  • Stsci Newsletter: 2017 Volume 034 Issue 02
    2017 - Volume 34 - Issue 02 Emerging Technologies: Bringing the James Webb Space Telescope to the World Like the rest of the Institute, excitement is building in the Office of Public Outreach (OPO) as the clock winds down for the launch of the James Webb Space Telescope. Our task is translating and sharing this excitement over groundbreaking engineering—and the scientific discoveries to come—with the public. Webb @ STScI In the lead-up to Webb’s launch in Spring 2019, the Institute continues its work as the science and operations center for the mission. The Institute has played a critical role in a number of recent Webb mission milestones. Updates on Hubble Operation at the Institute Observations with the Hubble Space Telescope continue to be in great demand. This article discusses Cycle 24 observing programs and scheduling efficiency, maintaining COS productivity into the next decade, keeping Hubble operations smooth and efficient, and ensuring the freshness of Hubble archive data. Hubble Cycle 25 Proposal Selection Hubble is in high demand and continues to add to our understanding of the universe. The peer-review proposal selection process plays a fundamental role in establishing a merit-based science program, and that is only possible thanks to the work and integrity of all the Time Allocation Committee (TAC) and review panel members, and the external reviewers. We present here the highlights of the Cycle 25 selection process. Using Gravity to Measure the Mass of a Star In a reprise of the famous 1919 solar eclipse experiment that confirmed Einstein's general relativity, the nearby white dwarf, Stein 2051 B, passed very close to a background star in March 2014.
    [Show full text]
  • Black Hole Paradoxes Mario Rabinowitz Armor Research 715 Lakemead Way Redwood City, CA 94062-3922 [email protected] Abstr
    Black Hole Paradoxes Mario Rabinowitz Armor Research 715 Lakemead Way Redwood City, CA 94062-3922 [email protected] Abstract The Black Hole enigma has produced many paradoxical concepts since its introduction by John Michell in 1783. As each paradox was resolved and our understanding about black holes matured, new paradoxes arose. A consensus regarding the resolution of some conundrums such as the Naked Singularity Paradox and the Black Hole Lost Information Paradox has still not been achieved. Black hole complementarity as related to the lost information paradox (LIP) and the LIP itself are challenged by gravitational tunneling radiation. Where possible, the paradoxes will be presented in historical context presenting the interplay of competing perspectives such as those of Bekenstein, Belinski, Chandrasekar, Hawking, Maldacena, Page, Preskill, Susskind, 't Hooft, Veneziano, Wald, Winterberg, Yilmaz, and others. The average kinetic energy of emitted particles may have a feature in common with themionic emission. A broad range of topics will be covered including: Why can or can't the formation of a black hole be observed? Can one observe a naked singularity like the one clothed by a black hole? What can come out of, or seem to come out of, a black hole? What happens to the information that falls into a black hole? Doesn't the resolution of the original black hole entropy paradox introduce an equally challenging puzzle? Related anomalies in the speed of light, the speed of gravity, the speed of inflation, and Mach's principle are considered. As we shall see, these paradoxes have served as an incentive for research to sharpen our thinking, and even to promote the development of both new theoretical and experimental physics.
    [Show full text]
  • The Nature of the Gravitational Vacuum
    The nature of the gravitational vacuum 1 Samir D. Mathur Department of Physics The Ohio State University Columbus, OH 43210, USA [email protected] Abstract The vacuum must contain virtual fluctuations of black hole microstates for each mass M. We observe that the expected suppression for M ≫ mp is counteracted by the large number Exp[Sbek] of such states. From string theory we learn that these microstates are extended objects that are resistant to compression. We ar- gue that recognizing this ‘virtual extended compression-resistant’ component of the gravitational vacuum is crucial for understanding gravitational physics. Remark- ably, such virtual excitations have no significant effect for observable systems like stars, but they resolve two important problems: (a) gravitational collapse is halted outside the horizon radius, removing the information paradox; (b) spacetime ac- arXiv:1905.12004v1 [hep-th] 28 May 2019 quires a ‘stiffness’ against the curving effects of vacuum energy; this ameliorates the cosmological constant problem posed by the existence of a planck scale Λ. 1Essay awarded an honorable mention in the Gravity Research Foundation 2019 Awards for Essays on Gravitation. Classical general relativity is expected to fail if we encounter curvature singularities. Two singularities of special interest are the central singularity of a black hole and the big bang singularity of cosmology. Both the associated spacetimes exhibit horizons, and the evolution equations are similar as well: the interior of a uniform collapsing dust ball maps, under time reversal, to a region of the dust cosmology. But the questions we face are very different in the two cases. With black holes, we ask how information can escape from the horizon in Hawking radiation.
    [Show full text]