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Thomas Pashby
University of Chicago
  1.  90
    Dirac's Prediction of the Positron: A Case Study for the Current Realism Debate.Thomas Pashby - 2012 - Perspectives on Science 20 (4):440-475.
    Much debate has ensued regarding the challenge to scientific realism provided by consideration of certain problematic episodes of theory change in the history of science. This paper contends that there is an interesting case which has been overlooked in this debate, namely the prediction of the positron by Dirac from his ‘hole’ theory, and its subsequent replacement by a theory which failed to contain a central, and essential, theoretical posit: the ‘Dirac sea’ of negative energy electrons. Accounting for this case (...)
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  2.  19
    Time and the Foundations of Quantum Mechanics.Thomas Pashby - unknown
    Quantum mechanics has provided philosophers of science with many counterintuitive insights and interpretive puzzles, but little has been written about the role that time plays in the theory. One reason for this is the celebrated argument of Wolfgang Pauli against the inclusion of time as an observable of the theory, which has been seen as a demonstration that time may only enter the theory as a classical parameter. Against this orthodoxy I argue that there are good reasons to expect certain (...)
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  3.  62
    How Do Things Persist? Location Relations in Physics and the Metaphysics of Persistence.Thomas Pashby - 2016 - Dialectica 70 (3):269-309.
    This paper investigates the use of theories of mechanics to provide answers to questions in the metaphysics of spatial location and persistence. Investigating spatial location, I find that in classical physics bodies pertend the region of space at which they are exactly located, while a quantum system spans a region at which it is exactly located. Following this analysis, I present a ‘no-go’ result which shows that quantum mechanics restricts the available options for locational persistence theories in an interesting way: (...)
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  4.  58
    Do Quantum Objects Have Temporal Parts?Thomas Pashby - unknown
    This paper provides a new context for an established metaphysical debate regarding the problem of persistence. I contend that perdurance can be precisely formulated in quantum mechanics due to an analogy with spatial parts, which I claim correspond to the decomposition of the quantum state provided by a localization scheme. However, I present a `no-go' result that rules out the existence of an analogous temporal localization scheme, and so argue that quantum objects cannot be said to perdure. I conclude by (...)
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  5.  46
    Time and Quantum Theory: A History and A Prospectus.Thomas Pashby - 2013 - Studies in the History and Philosophy of Modern Physics.
    In this paper I am concerned with analyzing in detail how ideas and expectations regarding the role of time in quantum theory arose and evolved in the early years of quantum mechanics (from 1925-27). The general theme is that expectations which seemed reasonable from the point of view of matrix mechanics and Dirac's q-number formalism became implausible in light of Dirac-Jordan transformation theory, and were dashed by von Neumann's Hilbert space formalism which came to replace it. Nonetheless, I will identify (...)
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  6.  8
    Time and Quantum Theory: A History and a Prospectus.Thomas Pashby - 2015 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 52 (Part A):24-38.
    In this paper I am concerned with analyzing in detail how ideas and expectations regarding the role of time in quantum theory arose and evolved in the early years of quantum mechanics. The general theme is that expectations which seemed reasonable from the point of view of matrix mechanics and Dirac's q-number formalism became implausible in light of Dirac-Jordan transformation theory, and were dashed by von Neumann's Hilbert space formalism which came to replace it. Nonetheless, I will identify two concerns (...)
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  7.  15
    Quantum Mechanics for Event Ontologists.Thomas Pashby - unknown
    In an event ontology, matter is 'made up of' events. This provides a distinctive foil to the standard view of a quantum state in terms of properties possessed by a system. Here I provide an argument against the standard view and suggest instead a way to conceive of quantum mechanics in terms of probabilities for the occurrence of events localized in space and time. To that end I construct an appropriate probability space for these events and give a way to (...)
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  8.  70
    Taking Times Out: Tense Logic as a Theory of Time.Thomas Pashby - 2015 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 50:13-18.
    Ulrich Meyer's book The Nature of Time uses tense logic to argue for a `modal' view of time, which replaces substantial times with `ersatz times' constructed using conceptually basic tense operators. He also argues against Bertrand Russell's relationist theory, in which times are classes of events, and against the idea that relativity compels the integration of time and space. I find fault with each of these negative arguments, as well as with Meyer's purported reconstruction of empty spacetime from tense operators (...)
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  9.  10
    At What Time Does a Quantum Experiment Have a Result?Thomas Pashby - unknown
    This paper provides a general method for defining a generalized quantum observable that supplies properly normalized conditional probabilities for the time of occurrence. This method treats the time of occurrence as a probabilistic variable whose value is to be determined by experiment and predicted by the Born rule. This avoids the problematic assumption that a question about the time at which an event occurs must be answered through instantaneous measurements of a projector by an observer, common to both Rovelli and (...)
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  10.  28
    Reply to Fleming: Symmetries, Observables, and the Occurrence of Events.Thomas Pashby - 2013 - Studies in the History and Philosophy of Modern Physics.
    In this article I reply to Fleming׳s response to my ‘Time and quantum theory: a history and a prospectus.’ I take issue with two of his claims: (i) that quantum theory concerns the (potential) properties of eternally persisting objects; (ii) that there is an underdetermination problem for Positive Operator Valued Measures (POVMs). I advocate an event-first view which regards the probabilities supplied by quantum theory as probabilities for the occurrence of physical events rather than the possession of properties by persisting (...)
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  11.  22
    Understanding Russell's Response to Newman.Thomas Pashby - unknown
    Russell's nonchalant response to Newman's apparently devastating critique of his structural realism presents a puzzle: if Russell conceded the point why did he not alter his theory or address the problem in print? I argue that Newman had merely pointed out an ambiguity in the formulation of Russell's theory in Analysis of Matter, and Russell already had the resources to avoid the problem through his contention that some relations are perceived. This concession gives his criterion of structural equivalence enough empirical (...)
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  12.  10
    Reply to Fleming.Thomas Pashby - unknown
    In this reply to Prof. Fleming's response to my `Time and Quantum Theory: A History and A Prospectus' I take issue with two of his claims: that quantum theory concerns the properties of eternally persisting objects; that there is a underdetermination problem for POVMs.
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  13.  10
    Reply to Fleming: Symmetries, Observables, and the Occurrence of Events.Thomas Pashby - 2015 - Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 52 (Part A):44-47.
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