University of California, Irvine
The Department of Logic and Philosophy of Science
PhD, 2009
Irvine, California, United States of America
PhilPapers Editorships
General Relativity
  •  139
    No no-go: A remark on time machines
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 42 (1): 74-76. 2011.
    We present a counterexample to Krasnikov's much discussed time machine no-go result. In addition, we prove a positive statement: a time machine existence theorem under a modest "no holes" assumption.
  •  114
    Can we know the global structure of spacetime?
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 40 (1): 53-56. 2009.
    Here, we briefly review the notion of observational indistinguishability within the context of classical general relativity. We settle a conjecture given by Malament (1977) concerning the subject and then strengthen the result considerably. The upshot is this: There seems to be a robust sense in which the global structure of every cosmological model is underdetermined
  •  94
    What Is a Physically Reasonable Space-Time?
    Philosophy of Science 78 (3): 410-420. 2011.
    Cosmologists often use certain global properties to exclude "physically unreasonable" cosmological models from serious consideration. But, on what grounds should these properties be regarded as "physically unreasonable" if we cannot rule out, even with a robust type of inductive reasoning, the possibility of the properties obtaining in our own universe?
  •  93
    The Geometry of Conventionality
    Philosophy of Science 81 (2): 233-247. 2014.
    There is a venerable position in the philosophy of space and time that holds that the geometry of spacetime is conventional, provided one is willing to postulate a “universal force field.” Here we ask a more focused question, inspired by this literature: in the context of our best classical theories of space and time, if one understands “force” in the standard way, can one accommodate different geometries by postulating a new force field? We argue that the answer depends on one’s theory. In Newt…Read more
  •  92
    On the existence of “time machines” in general relativity
    Philosophy of Science 76 (5): 1020-1026. 2009.
    Within the context of general relativity, we consider one definition of a “time machine” proposed by Earman, Smeenk, and Wüthrich. They conjecture that, under their definition, the class of time machine spacetimes is not empty. Here, we prove this conjecture. †To contact the author, please write to: Department of Philosophy, University of Washington, Box 353350, Seattle, WA 98195‐3350; e‐mail:
  •  86
    Is prediction possible in general relativity?
    Foundations of Physics 38 (4): 317-321. 2008.
    Here we briefly review the concept of "prediction" within the context of classical relativity theory. We prove a theorem asserting that one may predict one's own future only in a closed universe. We then question whether prediction is possible at all (even in closed universes). We note that interest in prediction has stemmed from considering the epistemological predicament of the observer. We argue that the definitions of prediction found thus far in the literature do not fully appreciate this p…Read more
  •  84
    On force in cartesian physics
    Philosophy of Science 76 (3): 295-306. 2009.
    There does not seem to be a consistent way to ground the concept of “force” in Cartesian first principles. In this article, I first review the literature on the subject. Then, I offer an alternative interpretation of force—one that seems to be coherent and consistent with Descartes’ project. Not only does the new position avoid the problems of previous interpretations, but it does so in such a way as to support and justify those previous interpretations. *Received June 2007; revised June 2009. †…Read more
  •  70
    On the Possibility of Supertasks in General Relativity
    Foundations of Physics 40 (3): 276-288. 2010.
    Malament-Hogarth spacetimes are the sort of models within general relativity that seem to allow for the possibility of supertasks. There are various ways in which these spacetimes might be considered physically problematic. Here, we examine these criticisms and investigate the prospect of escaping them
  •  69
    Is spacetime hole-free?
    General Relativity and Gravitation. 2008.
    Here, we examine hole-freeness - a condition sometimes imposed to rule out seemingly artificial spacetimes. We show that under existing definitions (and contrary to claims made in the literature) there exist inextendible, globally hyperbolic spacetimes which fail to be hole-free. We then propose an updated formulation of the condition which enables us to show the intended result. We conclude with a few general remarks on the strength of the definition and then formulate a precise question which …Read more
  •  68
    Is the Universe As Large As It Can Be?
    Erkenntnis 81 (6): 1341-1344. 2016.
    In this note, we cast doubt on the requirement of spacetime inextendibility; it is not at all clear that our universe is “as large as it can be.”
  •  62
    Here we provide a proof that there exist closed timelike curves in Gödel spacetime with total acceleration less than 2π(9 + 6√3)^1/2. This answers a question posed by David Malament.
  •  54
    Epistemic “Holes” in Space-Time
    Philosophy of Science 83 (2): 265-276. 2016.
    A number of models of general relativity seem to contain “holes” that are thought to be “physically unreasonable.” One seeks a condition to rule out these models. We examine a number of possibilities already in use. We then introduce a new condition: epistemic hole-freeness. Epistemic hole-freeness is not just a new condition—it is new in kind. In particular, it does not presuppose a distinction between space-times that are “physically reasonable” and those that are not.
  •  48
    On Gödel and the Ideality of Time
    Philosophy of Science 83 (5): 1050-1058. 2016.
    Gödel's remarks concerning the ideality of time are examined. In the literature, some of these remarks have been somewhat neglected while others have been heavily criticized. In this note, we propose a clear and defensible sense in which Gödel's work bears on the question of whether there is an objective lapse of time in our world.
  •  46
    On Space-Time Singularities, Holes, and Extensions
    Philosophy of Science 81 (5): 1066-1076. 2014.
    Here, we clarify the relationship among three space-time conditions of interest: geodesic completeness, hole-freeness, and inextendibility. In addition, we introduce a related fourth condition: effective completeness.
  •  33
    A remark on ‘time machines’ in honor of Howard Stein
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 67 111-116. 2019.
  •  31
    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.
  •  27
    Why Be regular?, part I
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 65 122-132. 2019.
  •  27
    Here, we outline the basic structure of relativistic spacetime and record a number of facts. We then consider a distinction between local and global spacetime properties and provide important examples of each. We also examine two clusters of global properties and question which of them should be regarded as physically reasonable. The properties concern "singularities" and "time travel" and are therefore of some philosophical interest.
  •  26
    On the Inextendibility of Space-Time
    Philosophy of Science 84 (5): 1215-1225. 2017.
    It has been argued that spacetime must be inextendible – that it must be “as large as it can be” in some sense. Here, we register some skepticism with respect to this position.
  •  24
    Malament–Hogarth Machines
    British Journal for the Philosophy of Science. forthcoming.
    We show a clear sense in which general relativity allows for a type of "machine" which can bring about a spacetime structure suitable for the implementation of "supertasks."
  •  22
    Would two dimensions be world enough for spacetime?
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 63 100-113. 2018.
    We consider various curious features of general relativity, and relativistic field theory, in two spacetime dimensions. In particular, we discuss: the vanishing of the Einstein tensor; the failure of an initial-value formulation for vacuum spacetimes; the status of singularity theorems; the non-existence of a Newtonian limit; the status of the cosmological constant; and the character of matter fields, including perfect fluids and electromagnetic fields. We conclude with a discussion of what cons…Read more
  •  17
    Time machines
    Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics 48 (2): 124-127. 2014.
  •  13
    Here, we show that one may "time travel" in Gödel spacetime with less total acceleration than was previously known. This answers a question posed by Malament.
  •  13
    Some “No Hole” Spacetime Properties are Unstable
    Foundations of Physics 48 (11): 1539-1545. 2018.
    We show a sense in which the spacetime property of effective completeness—a type of “local hole-freeness” or “local inextendibility”—is not stable.
  •  12
    Here, formal tools are used to pose and answer several philosophical questions concerning space and time. The questions involve the properties of possible worlds allowed by the general theory of relativity. In particular, attention is given to various causal properties such as "determinism" and "time travel".
  •  5
    I investigate the principle *anything goes* within the context of general relativity. After a few preliminaries, I show a sense in which the universe is unknowable from within this context; I suggest that we 'keep our options open' with respect to competing models of it. Given the state of affairs, proceeding counter-inductively seems to be especially appropriate; I use this method to blur some of the usual lines between 'reasonable' and 'unreasonable' models of the universe. Along the way, one …Read more