DOCSLIB.ORG

Dilaton Black Holes with Electric Charge

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dilaton Black Holes with Electric Charge University of Texas Rio Grande Valley ScholarWorks @ UTRGV Physics and Astronomy Faculty Publications and Presentations College of Sciences 1994 Dilaton black holes with electric charge Malik Rakhmanov The University of Texas Rio Grande Valley, [email protected] Follow this and additional works at: https://scholarworks.utrgv.edu/pa_fac Part of the Astrophysics and Astronomy Commons, and the Physics Commons Recommended Citation Rakhmanov, Malik. “Dilaton Black Holes with Electric Charge.” Physical Review D, vol. 50, no. 8, American Physical Society, Oct. 1994, pp. 5155–63, doi:10.1103/PhysRevD.50.5155. This Article is brought to you for free and open access by the College of Sciences at ScholarWorks @ UTRGV. It has been accepted for inclusion in Physics and Astronomy Faculty Publications and Presentations by an authorized administrator of ScholarWorks @ UTRGV. For more information, please contact [email protected], [email protected]. PHYSICAL REVIEWER D VOLUME 50, NUMBER 8 15 OCTOBER 1994 Dilaton black holes with electric charge Malik Rakhmanov California Institute of Technology, Pasadena, California 91125 (Received 3 May 1994) New static spherically symmetric solutions of the Einstein-Maxwell gravity with the dilaton field are found. The solutions correspond to black holes and naked singularities. In addition to mass and electric charge these solutions are labeled by a new parameter, the dilaton charge of the black hole. Depending on the values of electric and dilaton charges there are different types of solutions. The solutions exhibit a new type of a symmetry. Namely one solution transforms into another when the mass and the dilaton charge are interchanged. We also found that there is a finite interval of values of electric charge for which no black hole can exist. This gap separates two different types of solutions. Inside the gap the solution can exist only if the dilaton charge is exactly equal to the negative of the mass. The behavior of the solutions in the extremal regime is also analyzed. PACS number(s): 04.70.—s, 04.20.Jb I. INTRODUCTION no horizon anymore. The surface of metric discontinuity becomes the surface where the scalar curvature diverges. The low-energy limit includes scalar of string theory a In this case the arguments of [3] do not apply because the dilaton field, which is massless in all 6nite orders of per- surface integral diverges. This leaves the possibility for turbation theory [1]. However, in order not to conflict the existence of the scalar 6eld in the exterior of a black with classical tests of the tensor character of gravity, the hole if one admits singularities at finite radii. However, physical dilaton should have mass. This mass is assumed on very general grounds it is unlikely that such a surface to arise due to nonperturbative features of the quantum of singularities can ever appear. theory. At the classical level, and at distance scales small In this paper we will not discuss all these issues. Here compared to the dilaton Compton wavelength, we can we simply assume that there is a scalar 6eld in the exte- neglect the mass and study the effect of the dilaton on rior of the electrically charged black hole and study pos- low-energy physics. In particular, the dilaton modifies sible consequences of that. We will see that in most cases Maxwell's equations and it affects the geometry of the the dilaton 6eld destroys the horizons of the black hole space-time. For example, solutions that correspond to and leads to appearance of the curvature singularities. electrically charged black holes are modified by the pres- It will be shown that there is a one-parameter family of ence of the dilaton. Such solutions were studied in [4]— spherically symmetric asymptotically Bat solutions with [10], where it was shown that the dilaton changes the different dilaton charges. For a particular choice of the causal structure of the black hole and leads to curvature dilaton charge the solution reduces to the one obtained singularities at 6nite radii. ob- The black hole solution in [9], from now on referred to as the Garfinkle-Horowitz- tained in was also extensively [9] studied in connection Strominger (GHS) solution. This is the only true black with extremal dilaton black holes. It was argued that hole solution of the entire family. The other solutions such a black hole behaves like an elementary particle in correspond to naked singularities of different types. the sense that its excitation spectrum has an energy gap We will use geometrical units c = G = 1 throughout [»1-[»1 the paper. The line interval for a static spherically sym- Although the dilaton 6eld naturally arises in string the- metric space-time can be written as ory its existence &om the point of view of general relativ- ity is quite problematic. A generic scalar 6eld can violate ds = ndt +P—dr +p (de +sin Hdrp ), the equivalence principle; see the discussion in [2]. On the other hand, in black hole physics the inclusion of a scalar where a, P, and p are functions of the radial coordi- 6eld leads to the appearance of a "baryon number" as- nate r only. The solution that corresponds to the black sociated with the field. In the case of the dilaton field hole with mass M and electric charge Q is given by the this is the dilaton charge. It is generally believed that no Reissner-Nordstrom metric with p (r) = r and parameters other than mass, electric charge, and angular = = —— —— momentu~ can be associated with a black hole (see [3]). a'(r) s '(r) (1 ') (1 ), This conjecture essentially rules out the existence of the scalar field in the exterior of a static black hole. Indeed, if where we assume that the black hole has a regular horizon, then r1,2 =M+ QM2 Q2 following the arguments in [3] we arrive at the conclu- sion that the scalar field must be constant. On the other This solution has two horizons r = ri z when Q ( M . hand, the inclusion of the scalar field immediately results If Q = M the two horizons coincide and the black hole in singularities at the horizon. Strictly speaking, there is is said to be extremal. In the case when Qz ) Mz there 0556-2821/94/50(8)/5155(9)/$06. 00 50 5155 1994 The American Physical Society 5156 MALIK RAXHMANOV SO are no horizons. II. ACTION AND SYMMETRIES The metric is divergent when r approaches rq or r2. However, invariant quantities made out of components of The form of the action in four dimensions is suggested the Riemann curvature tensor are regular at the horizons. by the low-energy limit of string theory ex- In particular, the scalar curvature is zero everywhere — 1 — — cept the origin, where the true singularity resides. S = ~~g~ (R 2V'„PV'"P e ~F„„F") d x. The geometry of space-time is very different in the presence of the dilaton. Even in the case of pure dilaton The equations of motion for the metric g„,the vector gravity, when there is no electromagnetic field, a singu- potential A„and the dilaton field P are larity appears at a 6nite radius. Inclusion of the dilaton P leads to the appearance of a G„„=8~T„„, conserved charge, the dilaton charge. In static space-time it is de6ned by 7'„(e ~F"")= 0 D = — VggdS". 1 4' V„V'"P+— ~F„„F""= 0. 2 The integration is taken over a spacelike surface enclosing The components of the Einstein tensor and the energy- the origin. The conservation means that the value of momentum tensor are given in Appendix. the dilaton charge does not depend on the choice of the The symmetries of the action are general covariance surface. This is a simple consequence of the equation of and gauge symmetry. In addition, the action is invariant motion for the scalar field: V'„V"P= 0. under the global scale transformations Static spherically symmetric solutions of the Einstein equations and the dilaton equation are completely de- fined by the dilaton charge D and the mass M. The metric components are given by A„(x)= e A„(z). (2) This freedom can be eliminated by specifying P, the value of the dilaton at infinity. If nonzero this value will result in a screening of the electric charge: qe2$ F(r m oo) = The dilaton field is de6ned up to an arbitrary constant, its value at infinity: In what follows we assume that P = 0. The equations for nonzero P can be obtained by suitable redefinitions. (4) The Nother current corresponding to the global scale transformations is The constant is irrelevant and can be set to zero. The J„=V'„P+e ~F„A". quantity that plays the role of the Schwarzschild radius is defined by Note that this current is not gauge invariant. How- ever the conserved charge, associated with the current, is r, = 2/M2 + D2. gauge invariant provided that only those gauge transfor- mations that vanish at in6nity are allowed. Thus the metric shows a singularity at r = r, . Unlike the Schwarzschild and the Reissner-Nordstrom solutions this III. EQUATIONS OF MOTION is a true singularity. This can be seen from the formula for the scalar curvature: The metric for a static spherically symmetric space- is form metric remains 2D2 time given by Eq. (1). This of the = unchanged under the following transformation, which is B(r) 2+ 2M 2M p re f' —p rs a remnant of general coordinate invariance: 2 (dr) r + r and -+ Therefore, the scalar curvature becomes infinite as r ap- P P (dr proaches r, for any nonzero value of the dilaton charge.
Load more

Recommended publications
  • Limits on New Physics from Black Holes Arxiv:1309.0530V1
    Limits on New Physics from Black Holes Clifford Cheung and Stefan Leichenauer California Institute of Technology, Pasadena, CA 91125 Abstract Black holes emit high energy particles which induce a finite density potential for any scalar field φ coupling to the emitted quanta. Due to energetic considerations, φ evolves locally to minimize the effective masses of the outgoing states. In theories where φ resides at a metastable minimum, this effect can drive φ over its potential barrier and classically catalyze the decay of the vacuum. Because this is not a tunneling process, the decay rate is not exponentially suppressed and a single black hole in our past light cone may be sufficient to activate the decay. Moreover, decaying black holes radiate at ever higher temperatures, so they eventually probe the full spectrum of particles coupling to φ. We present a detailed analysis of vacuum decay catalyzed by a single particle, as well as by a black hole. The former is possible provided large couplings or a weak potential barrier. In contrast, the latter occurs much more easily and places new stringent limits on theories with hierarchical spectra. Finally, we comment on how these constraints apply to the standard model and its extensions, e.g. metastable supersymmetry breaking. arXiv:1309.0530v1 [hep-ph] 2 Sep 2013 1 Contents 1 Introduction3 2 Finite Density Potential4 2.1 Hawking Radiation Distribution . .4 2.2 Classical Derivation . .6 2.3 Quantum Derivation . .8 3 Catalyzed Vacuum Decay9 3.1 Scalar Potential . .9 3.2 Point Particle Instability . 10 3.3 Black Hole Instability . 11 3.3.1 Tadpole Instability .
    [Show full text]
  • Spacetime Geometry from Graviton Condensation: a New Perspective on Black Holes
    Spacetime Geometry from Graviton Condensation: A new Perspective on Black Holes Sophia Zielinski née Müller München 2015 Spacetime Geometry from Graviton Condensation: A new Perspective on Black Holes Sophia Zielinski née Müller Dissertation an der Fakultät für Physik der Ludwig–Maximilians–Universität München vorgelegt von Sophia Zielinski geb. Müller aus Stuttgart München, den 18. Dezember 2015 Erstgutachter: Prof. Dr. Stefan Hofmann Zweitgutachter: Prof. Dr. Georgi Dvali Tag der mündlichen Prüfung: 13. April 2016 Contents Zusammenfassung ix Abstract xi Introduction 1 Naturalness problems . .1 The hierarchy problem . .1 The strong CP problem . .2 The cosmological constant problem . .3 Problems of gravity ... .3 ... in the UV . .4 ... in the IR and in general . .5 Outline . .7 I The classical description of spacetime geometry 9 1 The problem of singularities 11 1.1 Singularities in GR vs. other gauge theories . 11 1.2 Defining spacetime singularities . 12 1.3 On the singularity theorems . 13 1.3.1 Energy conditions and the Raychaudhuri equation . 13 1.3.2 Causality conditions . 15 1.3.3 Initial and boundary conditions . 16 1.3.4 Outlining the proof of the Hawking-Penrose theorem . 16 1.3.5 Discussion on the Hawking-Penrose theorem . 17 1.4 Limitations of singularity forecasts . 17 2 Towards a quantum theoretical probing of classical black holes 19 2.1 Defining quantum mechanical singularities . 19 2.1.1 Checking for quantum mechanical singularities in an example spacetime . 21 2.2 Extending the singularity analysis to quantum field theory . 22 2.2.1 Schrödinger representation of quantum field theory . 23 2.2.2 Quantum field probes of black hole singularities .
    [Show full text]
  • Black Hole Production and Graviton Emission in Models with Large Extra Dimensions
    Black hole production and graviton emission in models with large extra dimensions Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften vorgelegt beim Fachbereich Physik der Johann Wolfgang Goethe–Universit¨at in Frankfurt am Main von Benjamin Koch aus N¨ordlingen Frankfurt am Main 2007 (D 30) vom Fachbereich Physik der Johann Wolfgang Goethe–Universit¨at als Dissertation angenommen Dekan ........................................ Gutachter ........................................ Datum der Disputation ................................ ........ Zusammenfassung In dieser Arbeit wird die m¨ogliche Produktion von mikroskopisch kleinen Schwarzen L¨ochern und die Emission von Gravitationsstrahlung in Modellen mit großen Extra-Dimensionen untersucht. Zun¨achst werden der theoretisch-physikalische Hintergrund und die speziel- len Modelle des behandelten Themas skizziert. Anschließend wird auf die durchgefuhrten¨ Untersuchungen zur Erzeugung und zum Zerfall mikrosko- pisch kleiner Schwarzer L¨ocher in modernen Beschleunigerexperimenten ein- gegangen und die wichtigsten Ergebnisse zusammengefasst. Im Anschluss daran wird die Produktion von Gravitationsstrahlung durch Teilchenkollisio- nen diskutiert. Die daraus resultierenden analytischen Ergebnisse werden auf hochenergetische kosmische Strahlung angewandt. Die Suche nach einer einheitlichen Theorie der Naturkr¨afte Eines der großen Ziele der theoretischen Physik seit Einstein ist es, eine einheitliche und m¨oglichst einfache Theorie zu entwickeln, die alle bekannten Naturkr¨afte beschreibt.
    [Show full text]
  • Black Holes and Qubits
    Subnuclear Physics: Past, Present and Future Pontifical Academy of Sciences, Scripta Varia 119, Vatican City 2014 www.pas.va/content/dam/accademia/pdf/sv119/sv119-duff.pdf Black Holes and Qubits MICHAEL J. D UFF Blackett Labo ratory, Imperial C ollege London Abstract Quantum entanglement lies at the heart of quantum information theory, with applications to quantum computing, teleportation, cryptography and communication. In the apparently separate world of quantum gravity, the Hawking effect of radiating black holes has also occupied centre stage. Despite their apparent differences, it turns out that there is a correspondence between the two. Introduction Whenever two very different areas of theoretical physics are found to share the same mathematics, it frequently leads to new insights on both sides. Here we describe how knowledge of string theory and M-theory leads to new discoveries about Quantum Information Theory (QIT) and vice-versa (Duff 2007; Kallosh and Linde 2006; Levay 2006). Bekenstein-Hawking entropy Every object, such as a star, has a critical size determined by its mass, which is called the Schwarzschild radius. A black hole is any object smaller than this. Once something falls inside the Schwarzschild radius, it can never escape. This boundary in spacetime is called the event horizon. So the classical picture of a black hole is that of a compact object whose gravitational field is so strong that nothing, not even light, can escape. Yet in 1974 Stephen Hawking showed that quantum black holes are not entirely black but may radiate energy, due to quantum mechanical effects in curved spacetime. In that case, they must possess the thermodynamic quantity called entropy.
    [Show full text]
  • Introduction to Black Hole Entropy and Supersymmetry
    Introduction to black hole entropy and supersymmetry Bernard de Wit∗ Yukawa Institute for Theoretical Physics, Kyoto University, Japan Institute for Theoretical Physics & Spinoza Institute, Utrecht University, The Netherlands Abstract In these lectures we introduce some of the principles and techniques that are relevant for the determination of the entropy of extremal black holes by either string theory or supergravity. We consider such black holes with N =2andN =4 supersymmetry, explaining how agreement is obtained for both the terms that are leading and those that are subleading in the limit of large charges. We discuss the relevance of these results in the context of the more recent developments. 1. Introduction The aim of these lectures is to present a pedagogical introduction to re- cent developments in string theory and supergravity with regard to black hole entropy. In the last decade there have been many advances which have thoroughly changed our thinking about black hole entropy. Supersymmetry has been an indispensable ingredient in all of this, not just because it is an integral part of the theories we consider, but also because it serves as a tool to keep the calculations tractable. Comparisons between the macroscopic and the microscopic entropy, where the latter is defined as the logarithm of the degeneracy of microstates of a certain brane or string configuration, were first carried out in the limit of large charges, assuming the Bekenstein- Hawking area law on the macroscopic (supergravity) side. Later on also subleading corrections could be evaluated on both sides and were shown to be in agreement, although the area law ceases to hold.
    [Show full text]
  • Spin Rate of Black Holes Pinned Down
    IN FOCUS NEWS 449–451; 2013) that used data from NASA’s NuSTAR mission, which was launched last year (see Nature 483, 255; 2012). Study leader Guido Risaliti, an astronomer at the Harvard-Smith- JPL-CALTECH/NASA sonian Center for Astrophysics in Cambridge, Massachusetts, says that NuSTAR provides access to higher-energy X-rays, which has allowed researchers to clarify the influence of the black hole’s gravity on the iron line. These rays are less susceptible than lower-energy X-rays to absorption by clouds of gas between the black hole and Earth, which some had speculated was the real cause of the distortion. In the latest study, astronomers calculated spin more directly (C. Done et al. Mon. Not. R. Astron. Soc. http://doi.org/nc2; 2013). They found a black hole some 150 million parsecs away with a mass 10 million times that of the Sun. Using the European Space Agency’s X-rays emitted by swirling disks of matter hint at the speed at which a supermassive black hole spins. XMM-Newton satellite, they focused not on the iron line but on fainter, lower-energy ASTROPHYSICS X-rays emitted directly from the accretion disk. The spectral shape of these X-rays offers indirect information about the temperature of the innermost part of the disk — and the Spin rate of black temperature of this material is, in turn, related to the distance from the event horizon and the speed at which the black hole is spinning. The calculations suggest that, at most, the black holes pinned down hole is spinning at 86% of the speed of light.
    [Show full text]
  • Kaluza-Klein Theory, Ads/CFT Correspondence and Black Hole Entropy
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server IFIC–01–37 Kaluza-Klein theory, AdS/CFT correspondence and black hole entropy J.M. Izquierdoa1, J. Navarro-Salasb1 and P. Navarrob 1 a Departamento de F´ısica Te´orica, Universidad de Valladolid E{47011 Valladolid, Spain b Departamento de F´ısica Te´orica, Universidad de Valencia and IFIC, Centro Mixto Universidad de Valencia{CSIC E{46100 Burjassot (Valencia), Spain Abstract The asymptotic symmetries of the near-horizon geometry of a lifted (near-extremal) Reissner-Nordstrom black hole, obtained by inverting the Kaluza-Klein reduction, explain the deviation of the Bekenstein- Hawking entropy from extremality. We point out the fact that the extra dimension allows us to justify the use of a Virasoro mode decom- position along the time-like boundary of the near-horizon geometry, AdS Sn, of the lower-dimensional (Reissner-Nordstrom) spacetime. 2× 1e-mails: [email protected], [email protected]fic.uv.es, [email protected]fic.uv.es 1 1 Introduction The universality of the Bekenstein-Hawking area law of black holes could be explained if the density of the microscopic states is controlled by the con- formal symmetry [1]. A nice example of this philosophy is provided by the BTZ black holes [2]. The Bekenstein-Hawking entropy can be derived [3], via Cardy’s formula, from the two-dimensional conformal symmetry arising at spatial infinity of three-dimensional gravity with a negative cosmological constant [4]. Moreover, one can look directly at the black hole horizon and treat it as a boundary.
    [Show full text]
  • Black Holes and String Theory
    Black Holes and String Theory Hussain Ali Termezy Submitted in partial fulfilment of the requirements for the degree of Master of Science of Imperial College London September 2012 Contents 1 Black Holes in General Relativity 2 1.1 Black Hole Solutions . 2 1.2 Black Hole Thermodynamics . 5 2 String Theory Background 19 2.1 Strings . 19 2.2 Supergravity . 23 3 Type IIB and Dp-brane solutions 25 4 Black Holes in String Theory 33 4.1 Entropy Counting . 33 Introduction The study of black holes has been an intense area of research for many decades now, as they are a very useful theoretical construct where theories of quantum gravity become relevant. There are many curiosities associated with black holes, and the resolution of some of the more pertinent problems seem to require a quantum theory of gravity to resolve. With the advent of string theory, which purports to be a unified quantum theory of gravity, attention has naturally turned to these questions, and have remarkably shown signs of progress. In this project we will first review black hole solutions in GR, and then look at how a thermodynamic description of black holes is made possible. We then turn to introduce string theory and in particular review the black Dp-brane solutions of type IIB supergravity. Lastly we see how to compute a microscopic account of the Bekenstein entropy is given in string theory. 1 Chapter 1 Black Holes in General Relativity 1.1 Black Hole Solutions We begin by reviewing some the basics of black holes as they arise in the study of general relativity.
    [Show full text]
  • Thermodynamics of Stationary Axisymmetric Einstein-Maxwell Dilaton-Axion Black Hole Jiliang Jing CCAST (Worm Laboratory), P.O
    http://www.paper.edu.cn NUCLEAR PHYSICS B ELSEVIER Nuclear Physics B 476 (1996) 548-555 Thermodynamics of stationary axisymmetric Einstein-Maxwell dilaton-axion black hole Jiliang Jing CCAST (Worm Laboratory), P.O. Box 8730, Beijing 100080, China and Institute of Physics and Physics Department l, Hunan Normal University, Changsha, Hunan 410081, China Received 21 March 1996; accepted 23 April 1996 Abstract The thermodynamics of a stationary axisymmetric Einstein-Maxwell dilaton-axion (EMDA) black hole is investigated using general statistical physics methods. It is shown that entropy and energy have the same form as for the Kerr-Newman charged black hole, but temperature, heat capacity and chemical potential have a different form. However, it is shown that the Bardeen- Carter-Hawking laws of black hole thermodynamics are valid for the stationary axisymmetric EMDA black hole. The black hole possesses second-order phase transitions as does the Kerr- Newman black hole because its heat capacity diverges but both the Helmholtz free energy and entropy are continuous at some value of J and Q. Another interesting result is that the action I can be expressed as I=S+ ~rh J for general stationary black holes in which the external material contribution to mass and angular momentum vanishes. When J = 0, i.e., for static black holes, the result reduces to I = S. PACS: 04.60.+n; 97.60.Lf; 04.65.+e; ll.17.+y 1. Introduction Recently a lot of interest has arosen in obtaining classical dilaton-axion black hole solutions in string theory and investigating their properties [1-4]. In particular attention was focused on the thermodynamics of these black holes.
    [Show full text]
  • Four-Dimensional Black Holes with Scalar Hair in Nonlinear Electrodynamics
    Eur. Phys. J. C (2016) 76:677 DOI 10.1140/epjc/s10052-016-4526-6 Regular Article - Theoretical Physics Four-dimensional black holes with scalar hair in nonlinear electrodynamics José Barrientos1,2,a, P. A. González3,b, Yerko Vásquez4,c 1 Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile 2 Departamento de Enseñanza de las Ciencias Básicas, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile 3 Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército Libertador 441, Casilla 298-V, Santiago, Chile 4 Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de La Serena, Avenida Cisternas 1200, La Serena, Chile Received: 14 June 2016 / Accepted: 21 November 2016 © The Author(s) 2016. This article is published with open access at Springerlink.com Abstract We consider a gravitating system consisting of 1 Introduction a scalar field minimally coupled to gravity with a self- interacting potential and a U(1) nonlinear electromagnetic Hairy black holes are interesting solutions to Einstein’s the- field. Solving analytically and numerically the coupled sys- ory of gravity and also to certain types of modified gravity tem for both power-law and Born–Infeld type electrodynam- theories. The first attempts to couple a scalar field to gravity ics, we find charged hairy black hole solutions. Then we was done in an asymptotically flat spacetime finding hairy study the thermodynamics of these solutions and we find black hole solutions [1–3], but it was realized that these solu- that at a low temperature the topological charged black hole tions were not physically acceptable as the scalar field was with scalar hair is thermodynamically preferred, whereas the divergent on the horizon and stability analysis showed that topological charged black hole without scalar hair is thermo- they were unstable [4].
    [Show full text]
  • Black Hole Math Is Designed to Be Used As a Supplement for Teaching Mathematical Topics
    National Aeronautics and Space Administration andSpace Aeronautics National ole M a th B lack H i This collection of activities, updated in February, 2019, is based on a weekly series of space science problems distributed to thousands of teachers during the 2004-2013 school years. They were intended as supplementary problems for students looking for additional challenges in the math and physical science curriculum in grades 10 through 12. The problems are designed to be ‘one-pagers’ consisting of a Student Page, and Teacher’s Answer Key. This compact form was deemed very popular by participating teachers. The topic for this collection is Black Holes, which is a very popular, and mysterious subject among students hearing about astronomy. Students have endless questions about these exciting and exotic objects as many of you may realize! Amazingly enough, many aspects of black holes can be understood by using simple algebra and pre-algebra mathematical skills. This booklet fills the gap by presenting black hole concepts in their simplest mathematical form. General Approach: The activities are organized according to progressive difficulty in mathematics. Students need to be familiar with scientific notation, and it is assumed that they can perform simple algebraic computations involving exponentiation, square-roots, and have some facility with calculators. The assumed level is that of Grade 10-12 Algebra II, although some problems can be worked by Algebra I students. Some of the issues of energy, force, space and time may be appropriate for students taking high school Physics. For more weekly classroom activities about astronomy and space visit the NASA website, http://spacemath.gsfc.nasa.gov Add your email address to our mailing list by contacting Dr.
    [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]