DOCSLIB.ORG

Generalized De Sitter Space

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Generalized De Sitter Space Generalized De Sitter Space Pedro F. Gonz´alez-D´ıaz Centro de F´ısica “Miguel Catal´an”, Instituto de Matem´aticas y F´ısica Fundamental, Consejo Superior de Investigaciones Cient´ıficas, Serrano 121, 28006 Madrid (SPAIN) (September 14, 1999) This paper deals with some two-parameter solutions to the spherically symmetric, vacuum Einstein equations which, we argue, are more general than the de Sitter solution. The global structure of one such spacetimes and its extension to the multiply connected case have also been investigated. By using a six-dimensional Minkowskian embedding as its maximal extension, we check that the thermal properties of the considered solution in such an embedding space are the same as those derived by the usual Euclidean method. The stability of the generalized de Sitter space containing a black hole has been investigated as well by introducing perturbations of the Ginsparg-Perry type in first order approximation. It has been obtained that such a space perdures against the effects of these perturbations. PACS numbers: 04.20.Jb, 04.62.+v, 04.70.Dy I. INTRODUCTION equations can be written as µν µν In some respects de Sitter space is to cosmology what R =Λg , (1.1) hydrogen atom is to atomic physics. In most practical sit- with Λ the cosmological constant. Assuming then stat- uations they both become the first example where any re- icness for a general spherically symmetric metric spective new formalism, description or theory is brought to be checked out. Actually, since the very moment it 2 A 2 B 2 2 2 ds = e dt + e dr + r dΩ2, (1.2) was discovered one finds it difficult to encounter a paper − 2 2 2 2 on cosmology in which no mention is made of de Sitter with dΩ2 = dθ + sin θdφ the metric on the unit three- universe. Soon after its publication [1], Einstein sent a sphere, we obtain A = B and hence the Schwarschild-de series of letters to de Sitter [2] in which he did not ex- Sitter solution [4] − press entire approval to the de Sitter cosmology. Two main criticisms were raised by Einstein. Firstly, since it Λr2 2m eA = e−B =1 , (1.3) could only apply without any ’world material’, that is − 3 − r stars, he found the de Sitter metric to make no physical meaning, and secondly, Einstein argued that whereas one where the mass m comes about as an integration con- can always put a rigid circular hoop into de Sitter uni- stant. de Sitter’s static solution arises when we set m =0 verse at any sufficiently early, though nonzero time, there in Eq. (1.3), i.e. in the pure vacuum case. arXiv:gr-qc/9909094v1 30 Sep 1999 is no place in it at time t = 0. While the first criticism From a slightly more technical point of view, the de Sit- leaves de Sitter universe only as a good approximation ter space can be indentified [5] as a maximally symmet- for sufficiently tiny matter density (which actually is the ric space of constant positive curvature (positive Ricci real case), the second one is nothing but an expression of scalar) which is a solution to the Einstein equations (1.1) the Einstein disappeal to the existence of the big bang, with a positive cosmological constant Λ > 0. It can be an attitude which evidently overcomes de Sitter scenario. visualized as a five-hyperboloid [6], It is rather ironic however that, in spite of the Einstein 3 reservations, de Sitter obtained his cosmological solution v2 + w2 + x2 + y2 + z2 = , (1.4) by just introducing the cosmological term first considered − Λ by Einstein himself in the general-relativity field equa- embedded in E5, with the most general metric of the tions for a spherically symmetric spacetime without any de Sitter space being then that which is induced in this matter, that is by considering the simplest possible sca- embedding, i.e. nario meeting the essentials of Einstein ideas. The key differential point between de Sitter and Einstein [3] uni- ds2 = dv2 + dw2 + dx2 + dy2 + dz2. (1.5) verses is that in the latter a given matter density was − explicitly included, setting a preferred value of the cos- This has topology R S4, invariance group SO(4, 1), and mological constant so that the resulting solution repre- shows ten Killings vectors× (four boosts and six rotations). sented a static universe. On the contrary, in de Sitter What we have hitherto described corresponds to a de space the value of the cosmological constant is completely Sitter space with simply connected topology. Recently, arbitrary. In the absence of any matter, the Einstein Gott and Li [7] have also considered the important case of 1 a multiply connected de Sitter space. These authors im- ρ(r) a given function of the radial coordinate r, has been posed the identification symmetry of the universal cover- shown by Stephani [9] to be two, and therefore one should ing of Misner space [5] to the five-hyperboloid visualizing consider a six-dimensional Minkowski space as the most the de Sitter space, so inducing a boost transformation general embedding for it. This would mean that one of in the region w> v covered by the static metric of this the six degrees of freedom of the embedding space should space that makes this| | region multiply connected. In this become frozen in the case of the usual de Sitter metric, way, the event horizon of the de Sitter space becomes so pointing toward some lack of generality for this met- a (Cauchy) chronology horizon which defines the onset ric. In fact, let us take the function ρ(r) to be given of an interior nonchronal region which supports closed by ρ(r) = H2r2, with H = Λ/3, and write the six- timelike curves (CTC’s). The multiply connected de Sit- dimensional− Minkowski metric as ter space can be used to implement new boundary con- p 2 2 2 ditions for the universe according to which, rather than ds = dz0 + dzi , i =1, ..., 5 (2.1) being created from nothing, the universe created itself − [7]. embedding the de Sitter manifold according to e.g. the In this paper we argue that the static de Sitter space following coordinate transformations for all topologies actually corresponds to rather restricted 2 2 2 2 solutions of the Einstein field equations for a spheri- z0 = k 1 H r sinh(t/k), z1 = k 1 H r cosh(t/k) − − cally symmetric empty space which becomes curved only p p (2.2) by the action of quantum vacuum effects. We show that there exist more general solutions to this prob- lem, defined by two cosmological parameters, namely the z2 = f(r) (2.3) usual cosmological constant, and a new constant vacuum term could could be associated to vacuum effects whose backreaction over the spacetime geometry led to higher- z3 = r cos φ sin θ, z4 = r sin φ sin θ, z5 = r cos θ, (2.4) derivative terms in the gravitational action. The rest of the paper can be outlined as follows. In where k is an arbitrary, dimensional parameter to be Sec. II we discuss the physical arguments that lead to fixed later, and the function f(r), defining the new coor- obtaining a two-parameter, generalized de Sitter solu- dinate z2, is given by [10] tion, deriving the precise form of such a new solution. 2 2 2 df ′ 2 k (dρ/dr) +4ρ We investigate then the nature of the event horizons and = (f ) = . (2.5) the global structure of the new solution, and maximally dr − 4(1 + ρ) " # extend the metric beyond the apparent horizons, both in the simply connected and multiply connected cases. Taking for the arbitrary parameter k the inverse of the −1 −1 The thermal properties associated with the existence of surface gravity of de Sitter space, k = κc = H , these event horizons are studied in Sec. III by using we get then from Eq. (2.5) that the function f(r) be- the usual Euclidean procedure, and a new method based comes a constant, f0, for de Sitter space, and hence it on replacing the Kruskal maximal extension by the six- follows that the coordinate z2 no longer is a degree of dimensional embedding Minkowskian space as the back- freedom for this space. Therefore, though the de Sitter ground spacetime where we allow the propagation of a static metric can still be visualized as a six-hyperboloid, massless scalar field. In Sec. IV we investigate the ef- this is reducible to a five-hyperboloid defined for a re- −1 2 fects that different types of Ginsparg-Perry perturbations scaled cosmological constant ΛR =1/ Λ f0 /3 , and [8] have in the generalized Schwarzschild-de Sitter space, the embedding Minkowski metric becomes that− of a five- concluding that this space is stable to the action of such dimensional space. In what follows we interpret this re- perturbations in first order. Finally, we briefly summa- sult as being an indication that the known de Sitter solu- rize and conclude in Sec. V. tion is not the most general solution that corresponds to general relativity with no matter for consistent nonzero quantum-mechanical vacuum fluctuations, for the follow- II. A TWO-PARAMETER VACUUM SOLUTION ing reason. Einstein equations were initially thought of as satisfying the requirement that they should permit flat We start this section by noticing the sense in which the spacetime as a particular solution in the absence of mat- de Sitter space cannot be considered as the most general ter. By introducing the cosmological constant, Λ, Ein- solution to spherically symmetric Einstein equations for stein dropped [3] this requirement out and got a slightly the pure vacuum case.
Load more

Recommended publications
  • KKLT an Overview
    KKLT an overview THESIS submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in PHYSICS Author : Maurits Houmes Student ID : s1672789 Supervisor : Prof. dr. K.E. Schalm 2nd corrector : Prof. dr. A. Achucarro´ Leiden, The Netherlands, 2020-07-03 KKLT an overview Maurits Houmes Huygens-Kamerlingh Onnes Laboratory, Leiden University P.O. Box 9500, 2300 RA Leiden, The Netherlands 2020-07-03 Abstract In this thesis a detailed description of the KKLT scenario is given as well as as a comparison with later papers critiquing this model. An attempt is made to provide a some clarity in 17 years worth of debate. It concludes with a summary of the findings and possible directions for further research. Contents 1 Introduction 7 2 The Basics 11 2.1 Cosmological constant problem and the Expanding Universe 11 2.2 String theory 13 2.3 Why KKLT? 20 3 KKLT construction 23 3.1 The construction in a nutshell 23 3.2 Tadpole Condition 24 3.3 Superpotential and complex moduli stabilisation 26 3.4 Warping 28 3.5 Corrections 29 3.6 Stabilizing the volume modulus 30 3.7 Constructing dS vacua 32 3.8 Stability of dS vacuum, Original Considerations 34 4 Points of critique on KKLT 39 4.1 Flattening of the potential due to backreaction 39 4.2 Conifold instability 41 4.3 IIB backgrounds with de Sitter space and time-independent internal manifold are part of the swampland 43 4.4 Global compatibility 44 5 Conclusion 49 Bibliography 51 5 Version of 2020-07-03– Created 2020-07-03 - 08:17 Chapter 1 Introduction During the turn of the last century it has become apparent that our uni- verse is expanding and that this expansion is accelerating.
    [Show full text]
  • Quantum Theory of Scalar Field in De Sitter Space-Time
    ANNALES DE L’I. H. P., SECTION A N. A. CHERNIKOV E. A. TAGIROV Quantum theory of scalar field in de Sitter space-time Annales de l’I. H. P., section A, tome 9, no 2 (1968), p. 109-141 <http://www.numdam.org/item?id=AIHPA_1968__9_2_109_0> © Gauthier-Villars, 1968, tous droits réservés. L’accès aux archives de la revue « Annales de l’I. H. P., section A » implique l’accord avec les conditions générales d’utilisation (http://www.numdam. org/conditions). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright. Article numérisé dans le cadre du programme Numérisation de documents anciens mathématiques http://www.numdam.org/ Ann. Inst. Henri Poincaré, Section A : Vol. IX, n° 2, 1968, 109 Physique théorique. Quantum theory of scalar field in de Sitter space-time N. A. CHERNIKOV E. A. TAGIROV Joint Institute for Nuclear Research, Dubna, USSR. ABSTRACT. - The quantum theory of scalar field is constructed in the de Sitter spherical world. The field equation in a Riemannian space- time is chosen in the = 0 owing to its confor- . mal invariance for m = 0. In the de Sitter world the conserved quantities are obtained which correspond to isometric and conformal transformations. The Fock representations with the cyclic vector which is invariant under isometries are shown to form an one-parametric family. They are inequi- valent for different values of the parameter. However, its single value is picked out by the requirement for motion to be quasiclassis for large values of square of space momentum.
    [Show full text]
  • (Anti-)De Sitter Space-Time
    Geometry of (Anti-)De Sitter space-time Author: Ricard Monge Calvo. Facultat de F´ısica, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain. Advisor: Dr. Jaume Garriga Abstract: This work is an introduction to the De Sitter and Anti-de Sitter spacetimes, as the maximally symmetric constant curvature spacetimes with positive and negative Ricci curvature scalar R. We discuss their causal properties and the characterization of their geodesics, and look at p;q the spaces embedded in flat R spacetimes with an additional dimension. We conclude that the geodesics in these spaces can be regarded as intersections with planes going through the origin of the embedding space, and comment on the consequences. I. INTRODUCTION In the case of dS4, introducing the coordinates (T; χ, θ; φ) given by: Einstein's general relativity postulates that spacetime T T is a differential (Lorentzian) manifold of dimension 4, X0 = a sinh X~ = a cosh ~n (4) a a whose Ricci curvature tensor is determined by its mass- energy contents, according to the equations: where X~ = X1;X2;X3;X4 and ~n = ( cos χ, sin χ cos θ, sin χ sin θ cos φ, sin χ sin θ sin φ) with T 2 (−∞; 1), 0 ≤ 1 8πG χ ≤ π, 0 ≤ θ ≤ π and 0 ≤ φ ≤ 2π, then the line element Rµλ − Rgµλ + Λgµλ = 4 Tµλ (1) 2 c is: where Rµλ is the Ricci curvature tensor, R te Ricci scalar T ds2 = −dT 2 + a2 cosh2 [dχ2 + sin2 χ dΩ2] (5) curvature, gµλ the metric tensor, Λ the cosmological con- a 2 stant, G the universal gravitational constant, c the speed of light in vacuum and Tµλ the energy-momentum ten- where the surfaces of constant time dT = 0 have metric 2 2 2 2 sor.
    [Show full text]
  • Coordinate Systems in De Sitter Spacetime Bachelor Thesis A.C
    Coordinate systems in De Sitter spacetime Bachelor thesis A.C. Ripken July 19, 2013 Radboud University Nijmegen Radboud Honours Academy Abstract The De Sitter metric is a solution for the Einstein equation with positive cosmological constant, modelling an expanding universe. The De Sitter metric has a coordinate sin- gularity corresponding to an event horizon. The physical properties of this horizon are studied. The Klein-Gordon equation is generalized for curved spacetime, and solved in various coordinate systems in De Sitter space. Contact Name Chris Ripken Email [email protected] Student number 4049489 Study Physicsandmathematics Supervisor Name prof.dr.R.H.PKleiss Email [email protected] Department Theoretical High Energy Physics Adress Heyendaalseweg 135, Nijmegen Cover illustration Projection of two-dimensional De Sitter spacetime embedded in Minkowski space. Three coordinate systems are used: global coordinates, static coordinates, and static coordinates rotated in the (x1,x2)-plane. Contents Preface 3 1 Introduction 4 1.1 TheEinsteinfieldequations . 4 1.2 Thegeodesicequations. 6 1.3 DeSitterspace ................................. 7 1.4 TheKlein-Gordonequation . 10 2 Coordinate transformations 12 2.1 Transformations to non-singular coordinates . ......... 12 2.2 Transformationsofthestaticmetric . ..... 15 2.3 Atranslationoftheorigin . 22 3 Geodesics 25 4 The Klein-Gordon equation 28 4.1 Flatspace.................................... 28 4.2 Staticcoordinates ............................... 30 4.3 Flatslicingcoordinates. 32 5 Conclusion 39 Bibliography 40 A Maple code 41 A.1 Theprocedure‘riemann’. 41 A.2 Flatslicingcoordinates. 50 A.3 Transformationsofthestaticmetric . ..... 50 A.4 Geodesics .................................... 51 A.5 TheKleinGordonequation . 52 1 Preface For ages, people have studied the motion of objects. These objects could be close to home, like marbles on a table, or far away, like planets and stars.
    [Show full text]
  • A Brief Analysis of De Sitter Universe in Relativistic Cosmology
    Munich Personal RePEc Archive A Brief Analysis of de Sitter Universe in Relativistic Cosmology Mohajan, Haradhan Assistant Professor, Premier University, Chittagong, Bangladesh. 18 June 2017 Online at https://mpra.ub.uni-muenchen.de/83187/ MPRA Paper No. 83187, posted 10 Dec 2017 23:44 UTC Journal of Scientific Achievements, VOLUME 2, ISSUE 11, NOVEMBER 2017, PAGE: 1-17 A Brief Analysis of de Sitter Universe in Relativistic Cosmology Haradhan Kumar Mohajan Premier University, Chittagong, Bangladesh E-mail: [email protected] Abstract The de Sitter universe is the second model of the universe just after the publications of the Einstein’s static and closed model. In 1917, Wilhelm de Sitter has developed this model which is a maximally symmetric solution of the Einstein field equation with zero density. The geometry of the de Sitter universe is theoretically more complicated than that of the Einstein universe. The model does not contain matter or radiation. But, it predicts that there is a redshift. This article tries to describe the de Sitter model in some detail but easier mathematical calculations. In this study an attempt has been taken to provide a brief discussion of de Sitter model to the common readers. Keywords: de Sitter space-time, empty matter universe, redshifts. 1. Introduction The de Sitter space-time universe is one of the earliest solutions to Einstein’s equation of motion for gravity. It is a matter free and fully regular solution of Einstein’s equation with positive 3 cosmological constant , where S is the scale factor. After the publications of the S 2 Einstein’s static and closed universe model a second static model of the static and closed but, empty of matter universe was suggested by Dutch astronomer Wilhelm de Sitter (1872–1934).
    [Show full text]
  • Cosmological Spacetimes with Λ > 0
    Cosmological Spacetimes with ¤ > 0 Gregory J. Galloway¤ Department of Mathematics University of Miami 1 Introduction This paper is based on a talk given by the author at the BEEMFEST, held at the University of Missouri, Columbia, in May, 2003. It was indeed a great pleasure and priviledge to participate in this meeting honoring John Beem, whose many oustanding contributions to mathematics, and leadership in the ¯eld of Lorentzian geometry has enriched so many of us. In this paper we present some results, based on joint work with Lars Andersson [2], concerning certain global properties of asymptotically de Sitter spacetimes satisfying the Einstein equations with positive cosmological constant. There has been increased interest in such spacetimes in recent years due, ¯rstly, to observations concerning the rate of expansion of the universe, suggesting the presence of a positive cosmological constant in our universe, and, secondly, due to recent e®orts to understand quan- tum gravity on de Sitter space via, for example, some de Sitter space version of the AdS/CFT correspondence; cf., [4] and references cited therein. In fact, the results discussed here were originally motivated by results of Witten and Yau [21, 5], and related spacetime results on topological censorship [11], pertaining to the AdS/CFT correspondence. These papers give illustrations of how the geometry and/or topol- ogy of the conformal in¯nity of an asymptotically hyperbolic Riemannian manifold, or an asymptotically anti-de Sitter spacetime, can inuence the global structure of the manifold. In this vein, the results described here establish connections between the geometry/topology of conformal in¯nity and the occurence of singularities in asymptotically de Sitter spacetimes.
    [Show full text]
  • General Relativistic Static Fluid Solutions with Cosmological Constant
    General Relativistic Static Fluid Solutions with Cosmological Constant Diplomarbeit von Christian G. B¨ohmer aus Berlin eingereicht bei der Mathematisch-Naturwissenschaftlichen Fakult¨at der Universit¨at Potsdam arXiv:gr-qc/0308057v3 4 Feb 2006 durchgefuhrt¨ am Max-Planck-Institut fur¨ Gravitationsphysik - Albert-Einstein-Institut - in Golm unter Anleitung von Prof. Dr. Bernd G. Schmidt Contents 1 Introduction 3 2 Cosmological TOV equation 7 2.1 TheCosmologicalConstant . 7 2.2 Remarks on the Newtonian limit . 8 2.3 TOV-Λequation ......................... 8 2.4 Schwarzschild-anti-de Sitter and Schwarzschild-de Sitter so- lution ............................... 11 2.5 Newtonianlimits ......................... 13 2.5.1 Limit of Schwarzschild-anti-de Sitter and Schwarzschild- deSittermodels ..................... 13 2.5.2 Limit of the TOV-Λ equation . 13 3 Solutions with constant density 15 3.1 Spatial geometry of solutions . 16 3.2 Solutions with negative cosmological constant . 17 3.2.1 Stellar models with spatially hyperbolic geometry . 18 3.2.2 Joining interior and exterior solution . 20 3.2.3 Stellar models with spatially Euclidean geometry . 22 3.2.4 Stellar models with spatially spherical geometry . 24 3.3 Solutions with vanishing cosmological constant . 27 3.4 Solutions with positive cosmological constant . 28 3.4.1 Stellar models with spatially spherical geometry . 28 3.4.2 Solutions with exterior Nariai metric . 31 3.4.3 Solutions with decreasing group orbits at the boundary 33 3.4.4 Decreasing solutions with two regular centres . 35 3.4.5 The Einstein static universe . 37 3.4.6 Increasing solutions with two regular centres . 38 3.4.7 Solutions with geometric singularity .
    [Show full text]
  • Yet Another Family of Diagonal Metrics for De Sitter and Anti-De Sitter Spacetimes
    Yet another family of diagonal metrics for de Sitter and anti-de Sitter spacetimes Jiˇr´ıPodolsk´y,OndˇrejHruˇska Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University, Prague, V Holeˇsoviˇck´ach 2, 180 00 Praha 8, Czech Republic [email protected] and [email protected] July 11, 2017 Abstract In this work we present and analyze a new class of coordinate representations of de Sitter and anti-de Sitter spacetimes for which the metrics are diagonal and (typically) static and axially symmetric. Contrary to the well-known forms of these fundamental geometries, that usually correspond to a 1 + 3 foliation with the 3-space of a constant spatial curvature, the new metrics are adapted to a 2 + 2 foliation, and are warped products of two 2-spaces of constant curvature. This new class of (anti-)de Sitter metrics depends on the value of cosmological constant Λ and two discrete parameters +1; 0; −1 related to the curvature of the 2-spaces. The class admits 3 distinct subcases for Λ > 0 and 8 subcases for Λ < 0. We systematically study all these possibilities. In particular, we explicitly present the corresponding parametrizations of the (anti- )de Sitter hyperboloid, visualize the coordinate lines and surfaces within the global conformal cylinder, investigate their mutual relations, present some closely related forms of the metrics, and give transformations to standard de Sitter and anti-de Sitter metrics. Using these results, we also provide a physical interpretation of B-metrics as exact gravitational fields of a tachyon. 1 Introduction Almost exactly 100 years ago in 1917 Willem de Sitter published two seminal papers [1, 2] in which he presented his, now famous, exact solution of Einstein's gravitational field equations without matter but with a positive cosmological constant Λ.
    [Show full text]
  • 4. the Einstein Equations
    4. The Einstein Equations It is now time to do some physics. The force of gravity is mediated by a gravitational field. The glory of general relativity is that this field is identified with a metric gµ⌫(x) on a 4d Lorentzian manifold that we call spacetime. This metric is not something fixed; it is, like all other fields in Nature, a dynamical object. This means that there are rules which govern how this field evolves in time. The purpose of this section is to explore these rules and some of their consequences. We will start by understanding the dynamics of the gravitational field in the absence of any matter. We will then turn to understand how the gravitational field responds to matter – or, more precisely, to energy and momentum – in Section 4.5. 4.1 The Einstein-Hilbert Action All our fundamental theories of physics are described by action principles. Gravity is no di↵erent. Furthermore, the straight-jacket of di↵erential geometry places enormous restrictions on the kind of actions that we can write down. These restrictions ensure that the action is something intrinsic to the metric itself, rather than depending on our choice of coordinates. Spacetime is a manifold M, equipped with a metric of Lorentzian signature. An action is an integral over M.WeknowfromSection2.4.4 that we need a volume-form to integrate over a manifold. Happily, as we have seen, the metric provides a canonical volume form, which we can then multiply by any scalar function. Given that we only have the metric to play with, the simplest such (non-trivial) function is the Ricci scalar R.
    [Show full text]
  • Instanton Tunneling for De Sitter Space with Real Projective Spatial Sections
    Instanton Tunneling for De Sitter Space with Real Projective Spatial Sections Yen Chin Ong∗ (1.) Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, Chinay. (2.) Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-106 91 Stockholm, Sweden (3.) Riemann Center for Geometry and Physics, Leibniz Universit¨atHannover, Appelstrasse 2, 30167 Hannover, Germany Dong-han Yeomz Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei 10617, Taiwan The physics of tunneling from one spacetime to another is often understood in terms of instantons. For some instantons, it was recently shown in the literature that there are two complementary \interpretations" for their analytic continuations. Dubbed \something-to-something" and \nothing-to- something" interpretations, respectively, the former involves situation in which the initial and final hypersurfaces are connected by a Euclidean manifold, whereas the initial and final hypersurfaces in the latter case are not connected in such a way. We consider a de Sitter space with real projective 3 space RP spatial sections, as was originally understood by de Sitter himself. This original version of de Sitter space has several advantages over the usual de Sitter space with S3 spatial sections. In particular, the interpretation of the de Sitter entropy as entanglement entropy is much more natural. We discuss the subtleties involved in the tunneling of such a de Sitter space. I. DE SITTER SPACE ACCORDING TO metric tensor is a local quantity which is not sensitive to 3 DE SITTER: THE CASE FOR RP the global topology. This is the reason why Einstein's field equations | a system of differential equations | De Sitter space is a Lorentzian manifold of constant cannot uniquely fix the topology.
    [Show full text]
  • Arxiv:1703.04622V2 [Hep-Th] 18 Aug 2020 to the Static Patch Region
    Infrared Realization of dS2 in AdS2 Dionysios Anninos1 and Diego M. Hofman2 1 Institute for Advanced Study, 1 Einstein Drive, Princeton, NJ 85040 2 Institute for Theoretical Physics Amsterdam and Delta Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands Abstract We describe a two-dimensional geometry that smoothly interpolates between an asymptotically AdS2 geometry and the static patch of dS2. We find this `centaur' geometry to be a solution of dilaton gravity with a specific class of potentials for the dilaton. We interpret the centaur geometry as a thermal state in the putative quantum mechanics dual to the AdS2 evolved with the global Hamiltonian. We compute the thermodynamic properties and observe that the centaur state has finite entropy and positive specific heat. The static patch is the infrared part of the centaur geometry. We discuss boundary observables sensitive arXiv:1703.04622v2 [hep-th] 18 Aug 2020 to the static patch region. 1 Introduction We have come to think of theories of gravity containing spacetimes endowed with an asymptotic spatial boundary as quantum mechanical systems with a large number of degrees of freedom. The most concrete examples involve spacetimes which asymp- tote to a (d + 1)-dimensional anti-de Sitter geometry [1], in which case the quantum system in the ultraviolet is a d-dimensional quantum field theory enjoying conformal symmetries. In the special case d = 1, the theory is a conformally invariant quantum mechanics describing an AdS2 geometry, such as the one appearing in the near hori- zon of black holes with a vanishing horizon temperature.
    [Show full text]
  • Classical Geometry of De Sitter Spacetime in Arbitrary Dimensions
    hep-th/0212326 Classical Geometry of De Sitter Spacetime : An Introductory Review Yoonbai Kima,b,1, Chae Young Oha,2, and Namil Parka,3 aBK21 Physics Research Division and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746, Korea bSchool of Physics, Korea Institute for Advanced Study, 207-43, Cheongryangri-Dong, Dongdaemun-Gu, Seoul 130-012, Korea Abstract Classical geometry of de Sitter spacetime is reviewed in arbitrary dimensions. Top- ics include coordinate systems, geodesic motions, and Penrose diagrams with detailed calculations. arXiv:hep-th/0212326v1 29 Dec 2002 [email protected] [email protected] [email protected] 1 Contents 1 Introduction 2 2 Setup 3 3 Useful Coordinates 5 3.1 Global (closed) coordinates (τ, θ ), i =1, 2, ,d 1 ............. 6 i ··· − 3.2 Conformal coordinates (T, θi) .......................... 9 3.3 Planar (inflationary) coordinates (t, xi) ..................... 11 3.4 Static coordinates (t, r, θ ), a =1, 2, ,d 2 ................. 15 a ··· − 4 Geodesics 17 4.1 Global (closed) coordinates ............................ 17 4.2 Conformal coordinates .............................. 19 4.3 Planar (inflationary) coordinates ........................ 21 4.4 Static coordinates ................................. 24 5 Penrose Diagram 28 5.1 Static coordinates ................................. 29 5.2 Conformal coordinates .............................. 31 5.3 Planar (inflationary) coordinates ........................ 32 6 Discussion 33 A Various Quantities 34 A.1 Global (closed) coordinates ............................ 34 A.2 Conformal coordinates .............................. 35 A.3 Planar (inflationary) coordinates ........................ 36 A.4 Static coordinates ................................. 37 1 Introduction Cosmological constant Λ was originally introduced in general relativity with the motiva- tion to allow static homogeneous universe to Einstein equations in the presence of matter.
    [Show full text]