I distinguish between two versions of the black hole information-loss paradox. The first arises from apparent failure of unitarity on the spacetime of a completely evaporating black hole, which appears to be non-globally-hyperbolic; this is the most commonly discussed version of the paradox in the foundational and semipopular literature, and the case for calling it `paradoxical' is less than compelling. But the second arises from a clash between a fully-statistical-mechanical interpretation of black (...) class='Hi'>hole evaporation and the quantum-field-theoretic description used in derivations of the Hawking effect. This version of the paradox arises long before a black hole completely evaporates, seems to be the version that has played a central role in quantum gravity, and is genuinely paradoxical. After explicating the paradox, I discuss the implications of more recent work on AdS/CFT duality and on the `Firewall paradox', and conclude that the paradox is if anything now sharper. The article is written at a introductory level and does not assume advanced knowledge of quantum gravity. (shrink)

The information loss paradox is often presented as an unavoidable consequence of well-established physics. However, in order for a genuine paradox to ensue, not-trivial assumptions about, e.g., quantum effects on spacetime, are necessary. In this work we will be explicit about these additional, speculative assumptions required. We will also sketch a map of the available routes to tackle the issue, highlighting the, often overlooked, commitments demanded of each alternative. Finally, we will display the strong link between black (...) holes, the issue of information loss and the measurement problem. (shrink)

Recently, several philosophers and physicists have increasingly noticed the hegemony of unitarity in the black hole information loss discourse and are challenging its legitimacy in the face of the measurement problem. They proclaim that embracing non-unitarity solves two paradoxes for the price of one. Though I share their distaste over the philosophical bias, I disagree with their strategy of still privileging certain interpretations of quantum theory. I argue that information-restoring solutions can be interpretation-neutral because the (...) manifestation of non-unitarity in Hawking's original derivation is unrelated to what's found in collapse theories or generalized stochastic approaches, thereby decoupling the two puzzles. (shrink)

The black hole information loss paradox is a catch-all term for a family of puzzles related to black hole evaporation. For almost 50 years, the quest to elucidate the implications of black hole evaporation has not only sustained momentum, but has also become increasingly populated with proposals that seem to generate more questions than they purport to answer. Scholars often neglect to acknowledge ongoing discussions within black hole thermodynamics and statistical (...) mechanics when analyzing the paradox, including the interpretation of Bekenstein-Hawking entropy, which is far from settled. To remedy the dialectical gridlock, I have formulated an overarching, unified framework, which I call ``Black Hole Paradoxes'', that integrates the debates and taxonomizes the relevant `camps' or philosophical positions. -/- I demonstrate that black hole evaporation within Hawking's semi-classical framework insinuates how late-time Hawking radiation is an entangled global system, a contradiction in terms. The relevant forms of information loss are associated with a decrease in maximal Boltzmann entropy and an increase in global von Neumann entropy respectively, which engender what I've branded the ``paradox of phantom entanglement''. Prospective solutions are then tasked with demonstrating how late-time Hawking radiation is either exclusively an entangled subsystem, in which a black hole remnant lingers as an information safehouse, or exclusively an unentangled global system, in which information is evacuated to the exterior. -/- The disagreement between safehouse and evacuation solutions boils down to the statistical interpretation of thermodynamic black hole entropy, i.e., Bekenstein-Hawking entropy. Safehouse solutions attribute Bekenstein-Hawking entropy to a minority of black hole degrees of freedom, those that are associated with the horizon. Evacuation solutions, in contrast, attribute Bekenstein-Hawking entropy to all black hole degrees of freedom. I argue that the interpretation of Bekenstein-Hawking entropy is the litmus test to vet the overpopulated proposal space. So long as any proposal rejecting Hawking's original calculation independently derives black hole evaporation, globally conserves degrees of freedom and entanglement, preserves a version of semi-classical gravity at sub-Planckian scales, and describes black hole thermodynamics in statistical terms, then it counts as a genuine solution to the paradox. (shrink)

The black hole information paradox arises from an apparent conflict between the Hawking black hole radiation and the fact that time evolution in quantum mechanics is unitary. The trouble is that while the former suggests that information of a system falling into a black hole disappears, the latter implies that information must be conserved. In this work we discuss the current divergence in views regarding the paradox, we evaluate the role that (...) objective collapse theories could play in its resolution and we propose a link between spontaneous collapse events and microscopic virtual black holes. (shrink)

We discuss some recent work by Tim Maudlin concerning Black Hole Information Loss. We argue, contra Maudlin, that there is a paradox, in the straightforward sense that there are propositions that appear true, but which are incompatible with one another. We discuss the significance of the paradox and Maudlin's response to it.

A proper understanding of black hole complementarity as a response to the information loss paradox requires recognizing the essential role played by arguments for the applicability and limitations of effective semiclassical theories. I argue that this perspective sheds important light on the arguments advanced by Susskind, Thorlacius, and Uglum—although ultimately I argue that their position is unsatisfactory. I also consider the argument offered by ’t Hooft for the breakdown of microcausality around black holes, and conclude (...) that it relies on a mistaken treatment of measurement collapse. There is, however, a legitimate argumentative role for black hole complementarity, exemplified by the position of Kiem, Verlinde, and Verlinde, that calls for a more subtle analysis of the limitations facing our effective theories. (shrink)

Over the years, the so-called black hole information loss paradox has generated an amazingly diverse set of proposals. However, 40 years after the introduction of Hawking’s radiation, there continues to be a debate regarding whether the effect does, in fact, lead to an actual problem. In this paper we try to clarify some aspect of the discussion by describing two possible perspectives regarding the landscape of the information loss issue. Moreover, we advance a fairly (...) conservative point of view regarding the relation between evaporating black holes and the rest of physics, which leads us to advocate a generalized breakdown of unitarity. We conclude by exploring some implications of our proposal in relation with conservation laws. (shrink)

Belot, Earman, and Ruetsche (1999) dismiss the black hole remnant proposal as an inadequate response to the Hawking information loss paradox. I argue that their criticisms are misplaced and that, properly understood, remnants do offer a substantial reply to the argument against the possibility of unitary evolution in spacetimes that contain evaporating black holes. The key to understanding these proposals lies in recognizing that the question of where and how our current theories break down is (...) at the heart of these debates in quantum gravity. I also argue that the controversial nature of assessing the limits of general relativity and quantum field theory illustrates the significance of attempts to establish the proper borders of our effective theories. (shrink)

Niels Bohr famously argued that a consistent understanding of quantum mechanics requires a new epistemic framework, which he named complementarity . This position asserts that even in the context of quantum theory, classical concepts must be used to understand and communicate measurement results. The apparent conflict between certain classical descriptions is avoided by recognizing that their application now crucially depends on the measurement context. ;Recently it has been argued that a new form of complementarity can provide a solution to the (...) so-called information loss paradox. Stephen Hawking argues that the evolution of black holes cannot be described by standard unitary quantum evolution, because such evolution always preserves information, while the evaporation of a black hole will imply that any information that fell into it is irrevocably lost---hence a "paradox." Some researchers in quantum gravity have argued that this paradox can be resolved if one interprets certain seemingly incompatible descriptions of events around black holes as instead being complementary. ;In this dissertation I assess the extent to which this black hole complementarity can be undergirded by Bohr's account of the limitations of classical concepts. I begin by offering an interpretation of Bohr's complementarity and the role that it plays in his philosophy of quantum theory. After clarifying the nature of classical concepts, I offer an account of the limitations these concepts face, and argue that Bohr's appeal to disturbance is best understood as referring to these conceptual limits. ;Following preparatory chapters on issues in quantum field theory and black hole mechanics, I offer an analysis of the information loss paradox and various responses to it. I consider the three most prominent accounts of black hole complementarity and argue that they fail to offer sufficient justification for the proposed incompatibility between descriptions. ;The lesson that emerges from this dissertation is that we have as much to learn from the limitations facing our scientific descriptions as we do from the successes they enjoy. Because all of our scientific theories offer at best limited, effective accounts of the world, an important part of our interpretive efforts will be assessing the borders of these domains of description. (shrink)

The existence of White Hole (WH) has been suggested by Schwarzschild solution to the Einstein field equation as a time-reversed Black Hole (BH), besides there has not been observational evidence for their existence yet. Our idea of the “inverse universe”, in which we introduce the time-reversed kinematics as another geometric state, can explain that WH should appear in such a geometry after a matter falls into a BH. In this work, we present a new operation for WH (...) conversion from BH, and by using it the nearly infinity point on the universe, for instance the inside of BH, is geometrically connected to the inside of WH on the inverse universe. Such a conversion is useful to provide the simple solution to the problem of “information loss” in BH. Furthermore, we find another conversion point as the prior geometric state to the Big Bang, and we propose a new cosmology of cyclic universe. (shrink)

Presentations of black hole complementarity by van Dongen and de Haro, as well as by 't Hooft, suffer from a mistaken claim that interactions between matter falling into a black hole and the emitted Hawking-like radiation should lead to a failure of commutativity between space-like-related observables localized inside and outside the black hole. I show that this conclusion is not supported by our standard understanding of quantum interactions. We have no reason to believe that (...) near-horizon interactions will threaten microcausality. If these interactions reliably transfer information to the outgoing radiation, then this response to Hawking's information loss argument should amount to a version of the bleaching scenario. I argue that the challenge facing black hole complementarity is that of reconciling this commitment to bleaching with the expectation that the event horizon will be locally unremarkable. This challenge is most promisingly met by proposals that postulate a consistent account of the limitations of our local semi-classical theories, but no support is added to these postulates by appeals to verificationism or to the interactions considered by 't Hooft. (shrink)

Stephen Hawking has argued that universes containing evaporating black holes can evolve from pure initial states to mixed final ones. Such evolution is non-unitary and so contravenes fundamental quantum principles on which Hawking's analysis was based. It disables the retrodiction of the universe's initial state from its final one, and portends the time-asymmetry of quantum gravity. Small wonder that Hawking's paradox has met with considerable resistance. Here we use a simple result for C*-algebras to offer an argument for pure-to-mixed (...) state evolution in black hole evaporation, and review responses to the Hawking paradox with respect to how effectively they rebut this argument. (shrink)

The black hole information problem provides important clues for trying to piece together a quantum theory of gravity. Discussions on this topic have generally assumed that in a consistent theory of gravity and quantum mechanics, quantum theory is unmodified. In this review, we discuss the black hole information problem in the context of generalisations of quantum theory. In this preliminary exploration, we examine black holes in the setting of generalised probabilistic theories, in which (...) quantum theory and classical probability theory are special cases. We are able to calculate the time it takes information to escape a black hole, assuming that information is preserved. In quantum mechanics, information should escape pure state black holes after half the Hawking photons have been emitted, but we find that this get’s modified in generalisations of quantum mechanics. Likewise the black-hole mirror result of Hayden and Preskill, that information from entangled black holes can escape quickly, also get’s modified. We find that although information exits the black hole as predicted by quantum theory, it is fairly generic that it fails to appear outside the black hole at this point—something impossible in quantum theory due to the no-hiding theorem. The information is neither inside the black hole, nor outside it, but is delocalised. (shrink)

The oft-neglected issue of the causal structure in the flat spacetime approach to Einstein's theory of gravity is considered. Consistency requires that the flat metric's null cone be respected, but this does not automatically happen. After reviewing the history of this problem, we introduce a generalized eigenvector formalism to give a kinematic description of the relation between the two null cones, based on the Segre' classification of symmetric rank 2 tensors with respect to a Lorentzian metric. Then we propose a (...) method to enforce special relativistic causality by using the gauge freedom to restrict the configuration space suitably. A set of new variables just covers this smaller configuration space and respects the flat metric's null cone automatically. Respecting the flat metric's null cone ensures that the spacetime is globally hyperbolic, indicating that the Hawking black hole information loss paradox does not arise in the special relativistic approach to Einstein's theory. (shrink)

Information theory presupposes the notion of an epistemic agent, such as a scientist or an idealized human. Despite that, information theory is increasingly invoked by physicists concerned with fundamental physics, physics at very high energies, or generally with the physics of situations in which even idealized epistemic agents cannot exist. In this paper, I shall try to determine the extent to which the application of information theory in those contexts is legitimate. I will illustrate my considerations using (...) the case of black hole thermodynamics and Bekenstein's celebrated argument for his formula for the entropy of black holes. This example is particularly pertinent to the theme of the present collection because it is widely accepted as `empirical data' in notoriously empirically deprived quantum gravity, even though the laws of black hole thermodynamics have so far evaded direct empirical confirmation. (shrink)

I outline some of my work and results on my matter-gravity entanglement hypothesis, according to which the entropy of a closed quantum gravitational system is equal to the system’s matter-gravity entanglement entropy. The main arguments presented are: that this hypothesis is capable of resolving what I call the second-law puzzle, i.e. the puzzle as to how the entropy increase of a closed system can be reconciled with the asssumption of unitary time-evolution; that the black hole information (...) class='Hi'>loss puzzle may be regarded as a special case of this second law puzzle and that therefore the same resolution applies to it; that the black hole thermal atmosphere puzzle can be resolved by adopting a radically different-from-usual description of quantum black hole equilibrium states, according to which they are total pure states, entangled between matter and gravity in such a way that the partial states of matter and gravity are each approximately thermal equilibrium states ; that the Susskind–Horowitz–Polchinski string-theoretic understanding of black hole entropy as the logarithm of the degeneracy of a long string cannot be quite correct but should be replaced by a modified understanding according to which it is the entanglement entropy between a long string and its stringy atmosphere, when in a total pure equilibrium state in a suitable box, which ) goes over, at strong-coupling, to a black hole in equilibrium with its thermal atmosphere. The modified understanding in is based on a general result, which I also describe, which concerns the likely state of a quantum system when it is weakly coupled to an energy-bath and the total state is a random pure state with a given energy. This result generalizes Goldstein et al.’s ‘canonical typicality’ result to systems which are not necessarily small. (shrink)

In any theory satisfying the no-signaling principle correlations generated among spatially separated parties in a Bell-type experiment are subject to certain constraints known as monogamy relations. Recently, in the context of the black hole information loss problem it was suggested that these monogamy relations might be violated. This in turn implies that correlations arising in such a scenario must violate the no-signaling principle and hence can be used to send classical information between parties. Here, we (...) study the amount of information that can be sent using such correlations. To this aim, we first provide a framework associating them with classical channels whose capacities are then used to quantify the usefulness of these correlations in sending information. Finally, we determine the minimal amount of information that can be sent using signaling correlations violating the monogamy relation associated to the chained Bell inequalities. (shrink)

To what extent does the black hole information paradox lead to violations of quantum mechanics? I explain how black hole complementarity provides a framework to articulate how quantum characterizations of black holes can remain consistent despite the information paradox. I point out that there are two ways to cash out the notion of consistency in play here: an operational notion and a descriptive notion. These two ways of thinking about consistency lead to (at (...) least) two principles of black hole complementarity: an operational principle and a descriptive principle. Our background philosophy of science regarding realism/instrumentalism might initially lead us to prefer one principle over the other. However, the recent physics literature, which applies tools from quantum information theory and quantum computational complexity theory to various thought experiments involving quantum systems in or around black holes, implies that the operational principle is successful where the descriptive principle is not. This then lets us see that for operationalists the black hole information paradox might no longer be pressing. (shrink)

Black holes are arguably the most extraordinary physical objects we know in the universe. Despite our thorough knowledge of black hole dynamics and our ability to solve Einstein’s equations in situations of ever increasing complexity, the deeper implications of the very existence of black holes for our understanding of space, time, causality, information, and many other things remain poorly understood. In this paper I survey some of these problems. If something is going to be clear (...) from my presentation, I hope it will be that around black holes science and metaphysics become more interwoven than anywhere else in the universe. (shrink)

The relevance of gravitational boundary degrees of freedom and their dynamics in gravity quantization and black hole information has been explored in a series of recent works. In this work we further progress by focusing keenly on the genuine gravitational boundary degrees of freedom as the origin of black hole entropy. Wald’s entropy formula is scrutinized, and the reason that Wald’s formula correctly captures the entropy of a black hole examined. Afterwards, limitations of (...) Wald’s method are discussed; a coherent view of entropy based on boundary dynamics is presented. The discrepancy observed in the literature between holographic and Wald’s entropies is addressed. We generalize the entropy definition so as to handle a time-dependent black hole. Large gauge symmetry plays a pivotal role. Non-Dirichlet boundary conditions and gravitational analogues of Coleman-De Luccia bounce solutions are central in identifying the microstates and differentiating the origins of entropies associated with different classes of solutions. The result in the present work leads to a view that black hole entropy is entanglement entropy in a thermodynamic setup. (shrink)

We review some ideas about the quantum physics of black hole information storage and processing in terms of a general phenomenon of quantum criticality.

Black holes are extremely relativistic objects. Physical processes around them occur in a regime where the gravitational field is extremely intense. Under such conditions, our representations of space, time, gravity, and thermodynamics are pushed to their limits. In such a situation philosophical issues naturally arise. In this chapter I review some philosophical questions related to black holes. In particular, the relevance of black holes for the metaphysical dispute between presentists and eternalists, the origin of the second law (...) of thermadynamics and its relation to black holes, the problem of information, black holes and hypercomputing, the nature of determinsim, and the breakdown of predictability in black hole space-times. I maintain that black hole physics can be used to illuminate some important problems in the border between science and philosophy, either epistemology and ontology. (shrink)

Almost all of the entropy in the universe is in the form of Bekenstein–Hawking (BH) entropy of super-massive black holes. This entropy, if it satisfies Boltzmann’s equation S=logN\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$S=\log \mathcal{N}$$\end{document}, hence represents almost all the accessible phase space of the Universe, somehow associated to objects which themselves fill out a very small fraction of ordinary three-dimensional space. Although time scales are very long, it is believed that black holes will eventually (...) evaporate by emitting Hawking radiation, which is thermal when counted mode by mode. A pure quantum state collapsing to a black hole will hence eventually re-emerge as a state with strictly positive entropy, which constitutes the famous black hole information paradox. Expanding on a remark by Hawking we posit that BH entropy is a thermodynamic entropy, which must be distinguished from information-theoretic entropy. The paradox can then be explained by information return in Hawking radiation. The novel perspective advanced here is that if BH entropy counts the number of accessible physical states in a quantum black hole, then the paradox can be seen as an instance of the fundamental problem of statistical mechanics. We suggest a specific analogy to the increase of the entropy in a solvation process. We further show that the huge phase volume (N\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathcal{N}$$\end{document}), which must be made available to the universe in a gravitational collapse, cannot originate from the entanglement between ordinary matter and/or radiation inside and outside the black hole. We argue that, instead, the quantum degrees of freedom of the gravitational field must get activated near the singularity, resulting in a final state of the ‘entangled entanglement’ form involving both matter and gravity. (shrink)

In the standard formalism of quantum gravity, black holes appear to form statistical distributions of quantum states. Now, however, we can present a theory that yields pure quantum states. It shows how particles entering a black hole can generate firewalls, which however can be removed, replacing them by the ‘footprints’ they produce in the out-going particles. This procedure can preserve the quantum information stored inside and around the black hole. We then focus on a (...) subtle but unavoidable modification of the topology of the Schwarzschild metric: antipodal identification of points on the horizon. If it is true that vacuum fluctuations include virtual black holes, then the structure of space-time is radically different from what is usually thought. (shrink)

The generalized second law of thermodynamics states that entropy always increases when all event horizons are attributed with an entropy proportional to their area. We test the generalized second law by investigating the change in entropy when dust, radiation and black holes cross a cosmological event horizon. We generalize for flat, open and closed Friedmann–Robertson–Walker universes by using numerical calculations to determine the cosmological horizon evolution. In most cases, the loss of entropy from within the cosmological horizon is (...) more than balanced by an increase in cosmological event horizon entropy, maintaining the validity of the generalized second law of thermodynamics. However, an intriguing set of open universe models shows an apparent entropy decrease when black holes disappear over the cosmological event horizon. We anticipate that this apparent violation of the generalized second law will disappear when solutions are available for black holes embedded in arbitrary backgrounds. (shrink)

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 achieved 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. (shrink)

In the last few years holography has celebrated some important anniversaries: in 2010 the 50th anniversary of the light amplification by stimulated emission of radiation (LASER) invention; in 2011 the 40th anniversary of the Nobel Prize awarded to the Hungarian scientist Dennis Gabor for inventing holography and in 2012 the 50th anniversary of the first holograms. Holography can create an accurate visual simulation, with total parallax: a replica of the real object made of light, which has the real object’s visual (...) properties but is immaterial, intangible. The holographic images are volumetric and exist in a real and measurable space, and are not based on the Renaissance perspective, which can represent the three-dimensional physical space in a bi-dimensional one. In the near future, holography-based techniques will open up new possibilities in the visualization domain, allowing new visual worlds. In the meantime, holography can be a useful technical and theoretical tool for reflecting on how our everyday mediascape works. The media can produce, reproduce and transmit bi-dimensional images on flat supports. The media system has a high degree of coherence and the images share similar morphostructural rules, and thus can be transferred from one medium to another without any fundamental information loss: bi-dimensionality and image-support coincidently appear to be the basis of this high level of translatability. Conversely, holograms cannot be displayed through the usual media without losing their peculiarity: they require new displays, new visual media and new genres of communication, even if they hybridize with the existing media. Holography stands apart from the media realm, which in part explains the difficulties of this technique in emerging and integrating into the mediascape. Holography suggests a new visual universe within a culture where visual simulation is the most effective communication system, and it lets us reflect on the need for a more comprehensive definition of ‘image’. It is easy to imagine that future images will also be holographic and that we will communicate more and more through them, in a delicate balance between presence and absence, immediacy and remoteness, materiality and immateriality, matter and energy. Holography can work as a model in science, for example in the study of brain activity in the Holonomic Brain Theory, originated by Austrian psychologist Karl Pribram and initially developed in collaboration with physicist David Bohm to explain human cognition. Holography can also be a model in physics, for example in the idea of the physicist David Bohm of an ‘implicate order’ in the universe, where global structure can be found in each small part – the universe would be a gigantic and wonderfully detailed hologram. More recently, theoretical results on black holes suggest that the idea of a holographic universe is a viable hypothesis. And in the field of quantum gravity and string theories the ‘holographic principle’ suggests that the entire universe can be considered as a two-dimensional information structure, and that the three-dimensional world we observe is but a description at a macroscopic scale and at low energies. (shrink)

In this Article I argue that the emerging public/private nexus of surveillance involves the augmentation of state power and calls for new models of constitutional constraint. The key phenomenon is the role played by communications intermediaries in collecting the information that the state subsequently accesses. These intermediaries are not just powerful companies engaged in collecting and analyzing the information of users and the information they hold are not just business records. The key feature of these companies is (...) that, through their information practices and architecture, they mediate other relationships. I argue that this mediating function, and its underlying technological form, interacts with legal and social norms in ways that can lead to the erosion of constraints on state power. This Article maps two stories of erosion, rooted in two kinds of community displacement. The first involves the displacement of community participation in law enforcement and the emergence of “technological tattletales” where intermediaries cooperate with the state. Unlike citizen cooperation, this practice augments state power and undermines more traditional informal modes of constraint on state power. The second involves the displacement of national legal and political community. Communications intermediaries are often large multinational companies that operate in multiple jurisdictions and move their data to various datacenters across the world even as the individual data subject remains in one geographical location. Laws that treat nonresident aliens differently from residents and citizens can create “constitutional black holes” where the communications data of an individual is not protected by any constitutional constraints. (shrink)

We put forward a proposal that combines objective collapse models, developed in connection with quantum-foundational questions, with the so-called Weyl curvature hypothesis, introduced by Roger Penrose as an attempt to account for the very special initial state of the universe. In particular, we explain how a curvature dependence of the collapse rate in such models, an idea already shown to help in the context of black holes and information loss, could also offer a dynamical justification for Penrose's (...) conjecture. (shrink)

The commonalities of Douglas Walton's Slippery Slope Arguments and James Davies's Ways of Thinking are obvious: both are written by Canadian philosophers; both lie within the broad field of informal logic; and both make appeals in support of dialogical reasoning. But there the similarities end. The former is the work of a prolific author writing a treatise focussing narrowly on one topic within informal logic; the latter is the product of a newcomer to book-writing, and his is a textbook intended (...) for beginning students. (shrink)

Real business cycle theory, as exemplified by Fischer Black's Business Cycles and Equilibrium, posits that business cycles are due to random?technology shocks,? and not to monetary, fiscal or other government policies. Rational expectations and complete markets are supposed to enable decision makers to avoid the costly mistakes that would otherwise result from policies that distort incentives to borrow and invest. This paper questions the assumptions of rational expectations and complete markets from an Austrian?school perspective. It argues that decision makers (...) economize on information costs by basing their plans at least in part on the actual prices observed in the course of doing business, and that government regulations have impinged on the evolution of markets, leaving them far from complete. (shrink)

High throughput time-resolved observations of accreting collapsed objects at X-ray energies provide key information on the motions of matter orbiting a few gravitational radii away from black holes. Predictions of general relativity in the strong field regime, such as relativistic epicyclic motions, precession, light bending and the presence and radius of an innermost stable circular orbit in the close vicinity of a black hole can be verified by making use of two powerful diagnostics, namely relativistically broadened (...) \ lines and variability on dynamical timescales, quasi periodic oscillations in particular. Moreover tomography and reverberation techniques relying upon combined spectral timing and polarimetric timing provide an entirely new perspective in the field. Both the low and high spacetime curvature regimes of gravity can be probed by studying black holes of vastly different masses in X-ray binaries and Active Galactic Nuclei, opening up the possibility of testing also some alternative theories of gravity. To achieve these goals, very large area X-ray instrumentation with good spectral resolution and polarimetric capability is required. Prospects and projects in this area of research are briefly surveyed. (shrink)

In his book The Myth of Evil, Phillip Cole argues that we ought to abandon the concept of evil. Cole claims that the concept of evil forms part of a dualistic worldview that divides normal people from inhuman, demonic, and monstrous wrongdoers. Such monsters are found in fiction, Cole suggests, but not in reality, so evil is of no explanatory use. Yet even if there were actual evil persons, Cole maintains, evil would be a redundant, pseudo-explanatory concept, a psychological (...) class='Hi'>black hole that is of no use in our explanations of why people do wrong. Contrary to Cole's claims, evil does have the requisite form to function as an explanation, and thus, if there are any actual evil actions or persons, evil will be explanatorily useful. Cole is right to suggest that evil cannot provide a complete explanation for any actions, but none of our virtue or vice concepts can do so, and they are none the worse for that. Cole is also right to suggest that the concept of evil is often used to play certain narrative roles, but he fails to see that evil can play those roles only if it has an explanatorily useful form. While it is true that evil could be paraphrased out of explanations of actions without any loss of information, that does not show that the concept is explanatorily redundant. In fact, Cole's preferred alternative explanations of extreme wrongdoing that eschew appeals to evil are themselves inadequate because they fail to account for the directed and intentional nature of some extremely wrong actions. (shrink)

o an outsider, nothing might seem more ridiculous than the spectacle of grown men and women sitting around a conference table soberly discussing what would happen if a volume of the Encyclopedia Britannica were dropped down a black hole. Yet this very question lies at the heart of the "information paradox," a seeming contradiction to the laws of physics that is causing scientists to re-examine some of their most basic assumptions about how the universe is made.

In Crull it is argued that, in order to confront outstanding problems in cosmology and quantum gravity, interpretational aspects of quantum theory can by bypassed because decoherence is able to resolve them. As a result, Crull concludes that our focus on conceptual and interpretational issues, while dealing with such matters in Okon and Sudarsky, is avoidable and even pernicious. Here we will defend our position by showing in detail why decoherence does not help in the resolution of foundational questions in (...) quantum mechanics, such as the measurement problem or the emergence of classicality. (shrink)

Welcome to the world of cutting-edge math, physics, and neuroscience, where the search for the ultimate vacuum, the point of nothingness, ground zero of theory, has rendered the universe deep, rich, and juicy. "Modern physics has animated the void," says K. C. Cole in her entrancing journey into the heart of Nothing. Every time scientists and mathematicians think they have reached the ultimate void, new stuff appears: a black hole, an undulating string, an additional dimension of space or (...) time, repulsive anti-gravity, universes that breed like bunnies. Cole's exploration at the edge of everything is as animated and exciting as the void itself. Take Cole's hand on this adventure into the unknown, and you'll come back informed, amused, and excited. (shrink)

Black holes have their own thermodynamics including notions of entropy and temperature and versions of the three laws. After a light introduction to black hole physics, I recollect how black hole thermodynamics evolved in the 1970s, while at the same time stressing conceptual points which were given little thought at that time, such as why the entropy should be linear in the black hole's surface area. I also review a variety of attempts made (...) over the years to provide a statistical mechanics for black hole thermodynamics. Finally, I discuss the origin of the information bounds for ordinary systems that have arisen as applications of black hole thermodynamics. (shrink)

This essay hypothesizes that the Universe contains a self-reproducing neural network of Black Holes with computational abilities—i.e., the Universe can “think”! It then rephrases the Final Anthropic Principle to state: “Intelligent information-processing must come into existence in each new Universe to assure the birth of intelligent successor universes”. Continued research into the theory of Early Universe and Black Hole information storage, processing and retrieval is recommended, as are observational searches for time-correlated electromagnetic and gravitational wave (...) emission patterns from widely separated Black Hole transient events indicative of the existence of a universal inter-Black Hole faster-than-light communications network. (shrink)

Autonomous artificial intelligence (AI) systems can lead to unpredictable behavior causing loss or damage to individuals. Intricate questions must be resolved to establish how courts determine liability. Until recently, understanding the inner workings of “black boxes” has been exceedingly difficult; however, the use of Explainable Artificial Intelligence (XAI) would help simplify the complex problems that can occur with autonomous AI systems. In this context, this article seeks to provide technical explanations that can be given by XAI, and to (...) show how suitable explanations for liability can be reached in court. It provides an analysis of whether existing liability frameworks, in both civil and common law tort systems, with the support of XAI, can address legal concerns related to AI. Lastly, it claims their further development and adoption should allow AI liability cases to be decided under current legal and regulatory rules until new liability regimes for AI are enacted. (shrink)

The Probabilistic Spacetime Theory (PST) was first referenced in 2020 and published in complete form in 2021. The theory exists to facilitate developments in modern cosmology through specific predictive and explanatory assertions, both to drive and interpret research discoveries. This article describes an extensive appraisal of the theory’s demonstrated predictive accuracy and explanatory efficacy during its 3.5-year lifetime. The theory was found to have forecasted multiple astrophysical and cosmological findings such as black hole expansion without mass, gravity without (...) mass, an excess degree of muon precession beyond the Standard Model prediction, and the self-interaction of so-called “dark matter”. Research outcomes concerning the Hubble tension were also predicted and explicated. Additionally, the PST was found to offer explanations concerning many baffling observations, including the existence of primordial supermassive black holes, the ubiquitous existence of magnetism, and unexpected heat in intergalactic hydrogen clouds. Enigmatic high-profile theoretical issues were also addressed by the PST, including the black hole information paradox, black holes without a singularity, and the final parsec problem. Overall, the theory seems to have demonstrated substantial predictive and explanatory utility during its short lifetime. To facilitate further testing of the PST, predictions of current studies’ outcomes are offered. (shrink)

According to the universal entropy bound, the entropy (and hence information capacity) of a complete weakly self-gravitating physical system can be bounded exclusively in terms of its circumscribing radius and total gravitating energy. The bound’s correctness is supported by explicit statistical calculations of entropy, gedanken experiments involving the generalized second law, and Bousso’s covariant holographic bound. On the other hand, it is not always obvious in a particular example how the system avoids having too many states for given energy, (...) and hence violating the bound. We analyze in detail several purported counterexamples of this type, and exhibit in each case the mechanism behind the bound’s efficacy. (shrink)

The aim of this study is to determine the use of the blackboard by teachers of Islamic Culture and Ethics. For this purpose, the views and practices of the teachers regarding the use of the blackboard were examined. The study is important as it was conducted through a combination of interviews and observations and contributes to the literature on the subject. A case study design, which is one of the qualitative methods, was used in the study. The study was conducted (...) with nine Islamic Culture and Ethics teachers selected through purposive sampling method in the center of Bitlis province and in six middle schools. A semi-structured interview form and an observation form developed by the researcher were used as data collection tools in the study. The data obtained from the interviews and observations were analyzed for content and presented in table format and interpreted. The study findings reached themes related to blackboard usage education, usage purpose, usage principles, usage self-efficacy, usage frequency, and usage problems. As a result, the teachers considered themselves sufficient in terms of blackboard usage and had not participated in any training related to blackboard usage. Teachers used the blackboard mainly to add visuality to the lesson, attract attention, provide instant additional and summary information, ensure permanence of knowledge, and activate teachers and students. Teachers frequently used the blackboard in their lessons. However, since teachers used the blackboard without paying attention to usage principles and in an unplanned manner, they encountered various problems related to classroom management such as noise, disinterest, and time loss, and could not benefit from the blackboard at a sufficient level. Nevertheless, it was observed that teachers' use of the blackboard in class added visuality and liveliness to the lesson, attracted the attention and interest of the students, supported teacher explanations, facilitated lesson follow-up, provided a common working area for teachers and students, and supported other educational tools used in the lesson. It is recommended that in-service trainings based on effective use of the blackboard be provided to teachers by experts in the field. (shrink)

This second volume is a continuation of the first volume’s 20th century conceptual foundations of quantum physics extending its view to the principles and research fields of the 21st century. A summary of the standard concepts, from modern advanced experimental tests of 'quantum ontology’ to the interpretations of quantum mechanics, the standard model of particle physics, and the mainstream quantum gravity theories. A state-of-the-art treatise that reports on the recent developments in quantum computing, classical and quantum information theory, the (...) black holes information paradox and the holographic principle to quantum cosmology, with some attention on contemporary themes such as the Bose-Einstein condensates as also to the more speculative areas of quantum biology and quantum consciousness. A final chapter on the connections between the quantum realm and philosophical idealism concludes this volume. Considering how the media (sometimes also physicists) present quantum theory, which focuses only on highly dubious ideas and speculations backed by no evidence or, worse, promote pseudo-scientific hypes that fall regularly in and out of fashion, this is a ‘vademecum’ for those who look for a serious introduction and deeper understanding of the 21st century quantum theory. All topics are explained with a concise but rigorous intermediate level style which may, at times, require some effort. However, you will finally acquire an unparalleled background in the conceptual foundations of quantum physics, enabling you to distinguish between the real science backed by experimental facts and mere speculative interpretations. (shrink)

Black holes entered scientific literature as early as at the end of eighteenth century. They had been known at that time as dark stars, but their concept did not find its way to physics or astronomy, and had been abandoned for more than one hundred years. I shall sketch historical developments and discuss present mathematical and observational status of black holes.

Inspired by possible connections between gravity and foundational question in quantum theory, we consider an approach for the adaptation of objective collapse models to a general relativistic context. We apply these ideas to a list of open problems in cosmology and quantum gravity, such as the emergence of seeds of cosmic structure, the black hole information issue, the problem of time in quantum gravity and, in a more speculative manner, to the nature of dark energy and the (...) origin of the very special initial state of the universe. We conclude that objective collapse models offer a rather promising path to deal with all of these issues. (shrink)

We model a black hole spacetime as a causal set and count, with a certain definition, the number of causal links crossing the horizon in proximity to a spacelike or null hypersurface Σ. We find that this number is proportional to the horizon's area on Σ, thus supporting the interpretation of the links as the “horizon atoms” that account for its entropy. The cases studied include not only equilibrium black holes but ones far from equilibrium.

Stationary spacetimes containing a black hole have several properties akin to those of atoms. For instance, such spacetimes have only three classical degrees of freedom, or observables, which may be taken to be the mass, the angular momentum, and the electric charge of the hole. There are several arguments supporting a proposal originally made by Bekenstein that quantization of these classical degrees of freedom gives an equal spacing for the horizon area spectrum of black holes. We (...) review some of these arguments and introduce a specific Hamiltonian quantum theory of black holes. Our Hamiltonian quantum theory gives, among other things, a discrete spectrum for the classical observables, and it produces an area spectrum which is closely related to Bekenstein's proposal. We also present a foamlike model of horizons of spacetime. In our model spacetime horizon consists of microscopic Schwarzschild black holes. Applying our Hamiltonian approach to this model we find that the entropy of any horizon is one quarter of its area. (shrink)