24 found
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  1.  68
    Effective Spacetime: Understanding Emergence in Effective Field Theory and Quantum Gravity.Karen Crowther - 2016 - Cham: Springer.
    This book discusses the notion that quantum gravity may represent the "breakdown" of spacetime at extremely high energy scales. If spacetime does not exist at the fundamental level, then it has to be considered "emergent", in other words an effective structure, valid at low energy scales. The author develops a conception of emergence appropriate to effective theories in physics, and shows how it applies (or could apply) in various approaches to quantum gravity, including condensed matter approaches, discrete approaches, and loop (...)
  2. Inter-theory Relations in Quantum Gravity: Correspondence, Reduction and Emergence.Karen Crowther - 2018 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 63:74-85.
    Relationships between current theories, and relationships between current theories and the sought theory of quantum gravity (QG), play an essential role in motivating the need for QG, aiding the search for QG, and defining what would count as QG. Correspondence is the broad class of inter-theory relationships intended to demonstrate the necessary compatibility of two theories whose domains of validity overlap, in the overlap regions. The variety of roles that correspondence plays in the search for QG are illustrated, using examples (...)
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  3. When do we stop digging? Conditions on a fundamental theory of physics.Karen Crowther - 2019 - In Anthony Aguirre, Brendan Foster & Zeeya Merali (eds.), What is Fundamental? Cham: Springer Verlag. pp. 123-133.
    In seeking an answer to the question of what it means for a theory to be fundamental, it is enlightening to ask why the current best theories of physics are not generally believed to be fundamental. This reveals a set of conditions that a theory of physics must satisfy in order to be considered fundamental. Physics aspires to describe ever deeper levels of reality, which may be without end. Ultimately, at any stage we may not be able to tell whether (...)
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  4. Defining a crisis: the roles of principles in the search for a theory of quantum gravity.Karen Crowther - 2021 - Synthese 198 (Suppl 14):3489-3516.
    In times of crisis, when current theories are revealed as inadequate to task, and new physics is thought to be required—physics turns to re-evaluate its principles, and to seek new ones. This paper explores the various types, and roles of principles that feature in the problem of quantum gravity as a current crisis in physics. I illustrate the diversity of the principles being appealed to, and show that principles serve in a variety of roles in all stages of the crisis, (...)
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  5. Renormalizability, fundamentality and a final theory: The role of UV-completion in the search for quantum gravity.Karen Crowther & Niels Linnemann - 2017 - British Journal for the Philosophy of Science 70 (2):377–406.
    Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity (QG), where novel empirical data is lacking. One principle widely adopted in the search for QG is UV completion: the idea that a theory should (formally) hold up to all possible high energies. We argue---/contra/ standard scientific practice---that UV-completion is poorly-motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore (...)
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  6. What we cannot learn from analogue experiments.Karen Crowther, Niels S. Linnemann & Christian Wüthrich - 2019 - Synthese (Suppl 16):1-26.
    Analogue experiments have attracted interest for their potential to shed light on inaccessible domains. For instance, ‘dumb holes’ in fluids and Bose–Einstein condensates, as analogues of black holes, have been promoted as means of confirming the existence of Hawking radiation in real black holes. We compare analogue experiments with other cases of experiment and simulation in physics. We argue—contra recent claims in the philosophical literature—that analogue experiments are not capable of confirming the existence of particular phenomena in inaccessible target systems. (...)
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  7.  68
    Renormalizability, Fundamentality, and a Final Theory: The Role of UV-Completion in the Search for Quantum Gravity.Karen Crowther & Niels Linnemann - 2019 - British Journal for the Philosophy of Science 70 (2):377-406.
    Principles are central to physical reasoning, particularly in the search for a theory of quantum gravity, where novel empirical data are lacking. One principle widely adopted in the search for QG is ultraviolet completion: the idea that a theory should hold up to all possible high energies. We argue— contra standard scientific practice—that UV-completion is poorly motivated as a guiding principle in theory-construction, and cannot be used as a criterion of theory-justification in the search for QG. For this, we explore (...)
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  8. As below, so before: ‘synchronic’ and ‘diachronic’ conceptions of spacetime emergence.Karen Crowther - 2020 - Synthese 198 (8):7279-7307.
    Typically, a less fundamental theory, or structure, emerging from a more fundamental one is an example of synchronic emergence. A model emerging from a prior model upon which it nevertheless depends is an example of diachronic emergence. The case of spacetime emergent from quantum gravity and quantum cosmology challenges these two conceptions of emergence. Here, I propose two more-general conceptions of emergence, analogous to the synchronic and diachronic ones, but which are potentially applicable to the case of emergent spacetime: an (...)
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  9. Decoupling emergence and reduction in physics.Karen Crowther - 2015 - European Journal for Philosophy of Science 5 (3):419-445.
    An effective theory in physics is one that is supposed to apply only at a given length scale; the framework of effective field theory describes a ‘tower’ of theories each applying at different length scales, where each ‘level’ up is a shorter-scale theory. Owing to subtlety regarding the use and necessity of EFTs, a conception of emergence defined in terms of reduction is irrelevant. I present a case for decoupling emergence and reduction in the philosophy of physics. This paper develops (...)
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  10. (1 other version)What is the point of reduction in science?Karen Crowther - 2018 - Erkenntnis:1-24.
    The numerous and diverse roles of theory reduction in science have been insufficiently explored in the philosophy literature on reduction. Part of the reason for this has been a lack of attention paid to reduction2 (successional reduction)---although I here argue that this sense of reduction is closer to reduction1 (explanatory reduction) than is commonly recognised, and I use an account of reduction that is neutral between the two. This paper draws attention to the utility---and incredible versatility---of theory reduction. A non-exhaustive (...)
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  11.  12
    When Do We Stop Digging? Conditions on a Fundamental Theory of Physics.Karen Crowther - 2019 - In Anthony Aguirre, Brendan Foster & Zeeya Merali (eds.), What is Fundamental? Cham: Springer Verlag. pp. 123-133.
    In seeking an answer to the question of what it means for a theory to be fundamental, it is enlightening to ask why the current best theories of physics are not generally believed to be fundamental. This reveals a set of conditions that a theory of physics must satisfy in order to be considered fundamental. Physics aspires to describe ever deeper levels of reality, which may be without end. Ultimately, at any stage we may not be able to tell whether (...)
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  12. Spacetime Emergence: Collapsing the Distinction Between Content and Context?Karen Crowther - 2022 - In Shyam Wuppuluri & Ian Stewart (eds.), From Electrons to Elephants and Elections: Saga of Content and Context. Springer. pp. 379–402.
    Several approaches to developing a theory of quantum gravity suggest that spacetime—as described by general relativity—is not fundamental. Instead, spacetime is supposed to be explained by reference to the relations between more fundamental entities, analogous to `atoms' of spacetime, which themselves are not (fully) spatiotemporal. Such a case may be understood as emergence of \textit{content}: a `hierarchical' case of emergence, where spacetime emerges at a `higher', or less-fundamental, level than its `lower-level' non-spatiotempral basis. But quantum gravity cosmology also presents us (...)
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  13. Four Attitudes Towards Singularities in the Search for a Theory of Quantum Gravity.Karen Crowther & Sebastian De Haro - 2022 - In Antonio Vassallo (ed.), The Foundations of Spacetime Physics: Philosophical Perspectives. New York, NY: Routledge. pp. 223-250.
    Singularities in general relativity and quantum field theory are often taken not only to motivate the search for a more-fundamental theory (quantum gravity, QG), but also to characterise this new theory and shape expectations of what it is to achieve. Here, we first evaluate how particular types of singularities may suggest an incompleteness of current theories. We then classify four different 'attitudes' towards singularities in the search for QG, and show, through examples in the physics literature, that these lead to (...)
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  14. Levels of Fundamentality in the Metaphysics of Physics.Karen Crowther - manuscript
    Within physics there are two ways of establishing the relative fundamentality of one theory compared to another, via two senses of reduction: "inter-level" and "intra-level" (Crowther, 2018). The former is standardly recognised as roughly correlating with the chain of ontological dependence (i.e., the phenomena described by theories of macro-physics are typically supposed to be ontologically dependent on the entities/behaviour described by theories of micro-physics), and thus has been of interest to naturalised metaphysics. The latter, though, has not been considered interesting (...)
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  15.  93
    Appearing Out of Nowhere: The Emergence of Spacetime in Quantum Gravity.Karen Crowther - 2014 - Dissertation, University of Sydney
    Quantum gravity is understood as a theory that, in some sense, unifies general relativity (GR) and quantum theory, and is supposed to replace GR at extremely small distances (high-energies). It may be that quantum gravity represents the breakdown of spacetime geometry described by GR. The relationship between quantum gravity and spacetime has been deemed ``emergence'', and the aim of this thesis is to investigate and explicate this relation. After finding traditional philosophical accounts of emergence to be inappropriate, I develop a (...)
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  16.  88
    Introduction: Principles of quantum gravity.Karen Crowther & Dean Rickles - 2014 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 46 (2):135-141.
    In this introduction, we describe the rationale behind this special issue on Principles of Quantum Gravity. We explain what we mean by ‘principles’ and relate this to the various contributions. Finally, we draw out some general themes that can be found running throughout these contributions.
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  17.  50
    When theory breaks down outside of the laboratory.Karen Crowther - 2024 - Filosofisk Supplement 2024 (2-3):36-45.
    Driven neither by experiment nor anomalous observation, physicists are seeking a new fundamental theory of gravity---motivated, guided, and constrained by purely theoretical and philosophical concerns. Here, I briefly consider two of these issues: dreams of unification, and the resolution of spacetime singularities.
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  18.  56
    Spacetime functionalism in general relativity and quantum gravity.Karen Crowther, Niels S. Linnemann & Christian Wüthrich - 2020 - Synthese 199 (S2):221-227.
    Introduction for the Synthese Special Issue on Spacetime Functionalism.
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  19.  93
    Emergent spacetime according to effective field theory: From top-down and bottom-up.Karen Crowther - 2013 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 44 (3):321-328.
    The framework of effective field theory is a natural one in which to understand the claim that the spacetime of general relativity is an emergent low-energy phenomenon. I argue for a pragmatic understanding of EFT, given that the appropriate conception of emergence it suggests is necessarily epistemological in a sense. Analogue models of spacetime are examples of the top-down approach to EFT. They offer concrete illustrations of spacetime emergent within an EFT, and lure us toward a strong analogy between condensed (...)
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  20.  14
    L'emergenza dello spazio-tempo nella gravità quantistica e nella cosmologia quantistica.Karen Crowther - unknown
    Our best description of spacetime is provided by general relativity – yet, this theory is not thought to be fundamental. Instead, it is expected to be replaced by a theory of quantum gravity, which may not feature spacetime fundamentally. Models of quantum cosmology use quantum gravity to describe the ‘beginning’ of spacetime from the ‘big bang’ state, as well as the evolution of the universe at the level of quantum gravity. In this essay, I discuss the conditions under which spacetime (...)
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  21. Art, politics, and particle physics, with one eye on the past: Steven Weinberg: Third Thoughts. Cambridge, MA: The Belknap Press of Harvard University Press, 2018, 240pp, $25.95HB. [REVIEW]Karen Crowther - 2019 - Metascience 28 (2):331-334.
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  22.  72
    Review of Beyond the Dynamical Universe: Unifying Block Universe Physics and Time as Experienced by Michael Silberstein, W. M. Stuckey, and Timothy McDevitt. [REVIEW]Karen Crowther - 2019 - British Journal for the Philosophy of Science Review of Books 2019.
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  23.  70
    Reduction and Emergence in Science and Philosophy By Carl Gillett Cambridge University Press, 2016. 389pp., £52.99 ISBN: 9781107075351. [REVIEW]Karen Crowther - 2018 - Philosophy 93 (4):586-590.
  24.  7
    Silberstein et al.'s Beyond the Dynamical Universe. [REVIEW]Karen Crowther - 2019 - BJPS Review of Books.
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