Black Hole Thermodynamics in Semi-Classical and Superstring Theory (original) (raw)

THE QUANTUM PHYSICS OF BLACK HOLES: Results from String Theory

Annual Review of Nuclear and Particle Science, 2000

We review recent progress in our understanding of the physics of black holes. In particular, we discuss the ideas from string theory that explain the entropy of black holes from a counting of microstates of the hole, and the related derivation of unitary Hawking radiation from such holes.

Conceptual Analysis of Black Hole Entropy in String Theory

The microscopic state counting of the extremal Reissner-Nordström black hole performed by Andrew Strominger and Cumrun Vafa in 1996 has proven to be a central result in string theory. Here, with a philosophical readership in mind, the argument is presented in its contemporary context and its rather complex conceptual structure is analysed. In particular, we will identify the various inter-theoretic relations, such as duality and linkage relations, on which it depends. We further aim to make clear why the argument was immediately recognised as a successful accounting for the entropy of this black hole and how it engendered subsequent work that intended to strengthen the string theoretic analysis of black holes. Its relation to the formulation of the AdS/CFT conjecture will be briefly discussed, and the familiar reinterpretation of the entropy calculation in the context of the AdS/CFT correspondence is given. Finally, we discuss the heuristic role that Strominger and Vafa's microscopic account of black hole entropy played for the black hole information paradox. A companion paper analyses the ontology of the Strominger-Vafa black hole states, the question of emergence of the black hole from a collection of D-branes, and the role of the correspondence principle in the context of string theory black holes.

Lost horizon? – modeling black holes in string theory

European Journal for Philosophy of Science, 2021

The modeling of black holes is an important desideratum for any quantum theory of gravity. Not only is a classical black hole metric sought, but also agreement with the laws of black hole thermodynamics. In this paper, we describe how these goals are obtained in string theory. We review black hole thermodynamics, and then explicate the general stringy derivation of classical spacetimes, the construction of a simple black hole solution, and the derivation of its entropy. With that in hand, we address some important philosophical and conceptual questions: the confirmatory value of the derivation, the bearing of the model on recent discussions of the so-called 'information paradox', and the implications of the model for the nature of space. * Some of this work was performed under a collaborative agreement between the University of Illinois at Chicago and the University of Geneva and made possible by grant numbers 56314 and 61387 from the John Templeton Foundation. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the John Templeton Foundation. We also thank John Dougherty for considerable assistance at the start of this work.

Modern foundations for thermodynamics and the stringy limit of black hole equilibria

We recall existing string theory work towards an understanding of black hole entropy and we argue that it is incomplete as it stands but we put forward a modified version, based on the author's earlier matter-gravity entanglement hypothesis, which, we claim, gives a more satisfactory understanding and also a resolution to the Information Loss Puzzle. This hypothesis pictures a black hole equilibrium state as an, overall pure, state, with given (approximate) energy, consisting of a black hole with its (mostly matter) atmosphere in a box and identifies the black hole's entropy with the pure state's matter-gravity entanglement entropy. We assume this equilibrium goes over, at weak string-coupling, to a pure state with similar energy consisting of a long string with a stringy atmosphere and that the matter-gravity entanglement entropy goes over to the entanglement entropy between (approximately) the long string and the stringy atmosphere. We also recall recent work (in a non-gravitational context) towards modern foundations for thermodynamics, where, in place of a total microcanonical ensemble, one assumes that a total system, consisting of a small (sub)system and an energy bath, is in a (random) pure state with energy in a given narrow range and shows that the small subsystem will then find itself to be in a thermal (Gibbs) state. We present a new set of formulae, obtained by the author in a companion paper, which generalize the setting of that work to cases where the system and energy bath are of comparable size. We apply these formulae to a simple model for our string equilibrium where the densities of states of the long string (replacing our energy bath) and stringy atmosphere (replacing our system) both grow exponentially. We find, for our picture of black hole equilibrium, a temperature of the order of the Hawking temperature and an entropy of the order of the Hawking entropy thus adding to the evidence for the viablity of our matter-gravity entanglement hypothesis and of our picture of black-hole equilibrium states.

Superstrings, Gauge Fields and Black Holes

International Journal of Modern Physics A, 2001

There has been spectacular progress in the development of string and superstring theories since its inception thirty years ago. Development in this area has never been impeded by the lack of experimental confirmation. Indeed, numerous bold and imaginative strides have been taken and the sheer

Semiclassical (QFT) and Quantum (String) Rotating Black Holes and Their Evaporation: New Results

International Journal of Modern Physics, 2007

Combination of both quantum field theory (QFT) and string theory in curved backgrounds in a consistent framework, the string analogue model, allows us to provide a full picture of the Kerr-Newman black hole and its evaporation going beyond the current picture. We compute the quantum emission cross section of strings by a Kerr-Newmann black hole (KNbh). It shows the black hole emission at the Hawking temperature T sem in the early stage of evaporation and the new string emission featuring a Hagedorn transition into a string state of temperature T s at the last stages. New bounds on J and Q emerge in the quantum string regime (besides the known ones of the classical/semiclassical QFT regime). The last state of evaporation of a semiclassical KNbh with mass M > m P l , angular momentum J and charge Q is a string state of temperature T s , string mass M s , J = 0 and Q = 0, decaying as usual quantum strings do into all kinds of particles.(Naturally, in this framework, there is no loss of information, (there is no paradox at all)). We compute the string entropy S s (m, j) from the microscopic string density of states of mass m and spin mode j, ρ(m, j). (Besides the Hagedorn transition at T s), we find for high j, (extremal string states j → m 2 α ′ c), a new phase transition at a temperature T sj = j/h T s , higher than T s. By precisely identifying the semiclassical and quantum (string) gravity regimes, we find a new formula for the Kerr black hole entropy S sem (M, J), as a function of the usual Bekenstein-Hawking entropy S (0) sem. For M ≫ m mP l and J < GM 2 /c, S (0) sem is the leading term, but for high angular momentum, (nearly extremal case J = GM 2 /c), a gravitational phase transition operates and the whole entropy S sem is drastically different from the Bekenstein-Hawking entropy S (0) sem. This new extremal black hole transition occurs at a temperature T semJ = J/h T sem , higher than the Hawking temperature T sem .

The signature of superstring balls near mini black holes at LHC

Astrophysics and Space Science, 2012

In this paper the information loss for fermionic superstrings "superstring balls" in mini black holes at LHC by extending the Gottesman and Preskill method to string theory and calculate the information transformation from the collapsing matter to the state of outgoing Hawking radiation is calculated. It is found that for all finite values of ω n , all information from all string emission processes experiences some degree of loss. It means that the string model is not sufficient to solve the information-loss problem. Then the fermionic superstring states at corresponding point are considered. The correspondence principle offered a unique opportunity to test the Horowitz and Maldacena mechanism at correspondence point "the centre of mass energies around (M s /(g s) 2)". To consider the super string states, a copy of the original Hilbert space is constructed with a set of operators of creation/annihilation that have the same anticommutation properties as the original ones. The total Hilbert space is the tensor product of the two spaces H physical ⊗ H unphysical , where in this case H physical denotes the physical quantum states space of the fermionic string. It is shown that fermionic string states can be represented by a maximally entangled two-mode squeezed state of the physical and unphysical spaces of fermionic string. Also, the entropy for these string states is calculated. It is observed that black hole entropy matches the fermionic superstring entropy at transition point. This means that our result is consistent with correspondence principle and thus

Black hole entropy from a highly excited elementary string

Physical Review D, 2003

Suggested correspondence between a black hole and a highly excited elementary string is explored. Black hole entropy is calculated by computing the density of states for an open excited string. We identify the square root of oscillator number of the excited string with Rindler energy of black hole to obtain an entropy formula which, not only agrees at the leading order with the Bekenstein-Hawking entropy, but also reproduces the logarithmic correction obtained for black hole entropy in the quantum geometry framework. This provides an additional supporting evidence for correspondence between black holes and strings.