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This essay is concerned with a number of related proposals that claim there is a link between spacetime topology and quantum entanglement. I indicate the extent to which these proposals can be understood as stating a duality, and then consider two general approaches to articulating such a duality: a “state-based” approach, under which one attempts to identify relevant topological states as dual to quantum entangled states; and an “observable-based” approach, under which one attempts to identify relevant topological observables as dual to quantum entangement observables. Both approaches are faced with issues, essentially due to the ambiguous nature of quantum entanglement, that remain to be addressed.

This essay considers an interpretation of the AdS/CFT correspondence under which the bulk and the boundary emerge from a more fundamental discrete system that realizes the structure of an erasure-protection quantum error-correcting code (QECC). I consider the extent to which this view underwrites the claim that spacetime is a QECC (as some authors have suggested), and how it fits into recent schemes of realist interpretations of dualities.

Intrinsic topologically ordered (ITO) condensed matter systems are claimed to exhibit two types of non-locality. The first is associated with topological properties and the second is associated with a particular type of quantum entanglement. These characteristics are supposed to allow ITO systems to encode information in the form of quantum entangled states in a topologically non-local way that protects it against local errors. This essay first clarifies the sense in which these two notions of non-locality are distinct, and then considers the extent to which they are exhibited by ITO systems. I will argue that while the claim that ITO systems exhibit topological non-locality is unproblematic, the claim that they also exhibit quantum entanglement non-locality is less clear, and this is due in part to ambiguities associated with the notion of quantum entanglement. Moreover, any argument that claims some form of "long-range" entanglement is necessary to explain topological properties is incomplete if it fails to provide a convincing reason why mechanistic explanations should be favored over structural explanations of topological phenomena.

Naturalness, as a guiding principle for effective field theories (EFTs), requires that there be no sensitive correlations between phenomena at low- and high-energy scales. This essay considers four reasons to adopt this principle: (i) natural EFTs exhibit modest empirical success; (ii) unnatural EFTs are improbable; (iii) naturalness underwrites what Williams (Stud Hist Philos Mod Phys 51:82, 2015) calls a “central dogma” of EFTs; namely, that phenomena at widely separated scales should decouple; and (iv) naturalness underwrites a non-trivial notion of emergence. I argue that the first three are not compelling reasons, whereas the fourth is.

Whether for temporary or long term use, mechanical circulatory support (MCS) has seen increased utilization and interest over the past several years. Even though these devices innately cause thrombocytopenia, co-administration of heparin anticoagulation carries the risk for heparin-induced thrombocytopenia (HIT). This poses challenges for practitioners as very few studies provide guidance for the management of this condition, particularly in this population. This has led to a wide spectrum of treatment protocols within current practice. This review was developed to bring together available literature on the management of HIT in patients with MCS along with practical experience and clinical opinion in order to help guide the management of these patients.

For some authors, an adequate notion of emergence must include an account of a mechanism by means of which emergent behavior is realized. This appeal to mechanism is problematic in the case of the fractional quantum Hall effect (FQHE). There is a consensus among physicists that the FQHE exhibits emergent phenomena, but there are at least four alternative explanations of the latter that, arguably, appeal to ontologically distinct mechanisms, both at the microphysics level and at the level of general organizing principles. In light of this underdetermination of mechanism, one is faced with the following options: (I) deny that emergence is present in the FQHE; (II) argue for the priority of one mechanistic explanation over the others; or (III) temper the desire for a mechanism-centric account of emergence. I will argue that there are good reasons to reject (I) and (II) and accept (III). In particular, I will suggest that a law-centric account of emergence does just fine in explaining the emergent phenomena associated with the FQHE.

Background: Recombinant and plasma-derived factor products, such as activated factor seven (rFVIIa) and four-factor prothrombin complex concentrate (4-factor PCC), have been used off-label for bleeding after cardiac surgery, but little evidence has been published regarding their efficacy and safety. Objective: To determine whether there is a difference in chest tube output in patients who have received 4-factor PCC or rFVIIa for critical postoperative bleeding associated with cardiovascular surgery. Methods: A retrospective chart review was conducted utilizing the electronic medical record system at a 657-bed community, tertiary care hospital in Nashville, Tennessee. Nonpregnant patients ≥18 years of age experiencing significant bleeding during cardiac surgery who received either PCC or rFVIIa perioperatively or postoperatively between April 2015 through December 2016 were eligible for inclusion. Patients were excluded if they received 4-factor PCC or rFVIIa for any indication other than bleeding during cardiac surgery or if they received both agents. Results: Data conclude that there is no significant difference in chest tube output 24 hours postoperatively between patients treated with 4-factor PCC or rFVIIa. There was no difference in bleeding, thromboembolic events, or re-exploration between the rFVIIa and 4-factor PCC groups, but there was a difference in units of fresh frozen plasma administered and hospital length of stay. Conclusion: 4-Factor PCC may be an equally efficacious alternative to rFVIIa for patients experiencing significant bleeding during cardiac surgery. There is no difference in chest tube output; therefore, there is no difference in bleeding—either at 24 hours postoperatively or total.

Research on quantum gravity (QG) has historically relied on appeals to guiding principles. This essay frames three such principles within the context of the condensed matter approach to QG. I first identify two distinct versions of this approach, and then consider the extent to which the principles of asymptotic safety, relative locality, and holography are supported by these versions. The general hope is that a focus on distinct versions of a single approach may provide insight into the conceptual and foundational significance of these principles.

Condensed matter approaches to quantum gravity suggest that spacetime emerges in the low-energy sector of a fundamental condensate. This essay investigates what could be meant by this claim. In particular, I offer an account of low-energy emergence that is appropriate to effective field theories in general, and consider the extent to which it underwrites claims about the emergence of spacetime in effective field theories of condensed matter systems of the type that are relevant to quantum gravity.

This essay considers the extent to which a concept of emergence can be associated with Effective Field Theories (EFTs). I suggest that such a concept can be characterized by microphysicalism and novelty underwritten by the elimination of degrees of freedom from a high-energy theory, and argue that this makes emergence in EFTs distinct from other concepts of emergence in physics that have appeared in the recent philosophical literature.

CPT invariance and the spin-statistics connection are typically taken to be essential properties in relativistic quantum field theories (RQFTs), insofar as the CPT and Spin-Statistics theorems entail that any state of a physical system characterized by an RQFT must possess these properties. Moreover, in the physics literature, they are typically taken to be properties of particles. But there is a Received View among philosophers that RQFTs cannot fundamentally be about particles. This essay considers what proofs of the CPT and Spin-Statistics theorems suggest about the ontology of RQFTs, and the extent to which this is compatible with the Received View. I will argue that such proofs suggest the Received View’s approach to ontology is flawed.

According to a Received View, relativistic quantum field theories (RQFTs) do not admit particle interpretations. This view requires that particles be localizable and countable, and that these characteristics be given mathematical expression in the forms of local and unique total number operators. Various results (the Reeh-Schlieder theorem, the Unruh Effect, Haag's theorem) then indicate that formulations of RQFTs do not support such operators. These results, however, do not hold for non-relativistic QFTs. I argue that this is due to the absolute structure of the classical spacetimes associated with such theories. This suggests that the intuitions that underlie the Received View's choice of mathematical representations of localizability and countability are non-relativistic. Thus, to the extent that such intuitions are inappropriate in the relativistic context, they should be abandoned when it comes to interpreting RQFTs.

Radical ontic structural realism (ROSR) claims that structure exists independently of objects that may instantiate it. Critics of ROSR contend that this claim is conceptually incoherent, insofar as, (i) it entails there can be relations without relata, and (ii) there is a conceptual dependence between relations and relata. In this essay I suggest that (ii) is motivated by a set-theoretic formulation of structure, and that adopting a category-theoretic formulation may provide ROSR with more support. In particular, I consider how a category-theoretic formulation of structure can be developed that denies (ii), and can be made to do work in the context of formulating theories in physics.

An influential claim in the physics literature states that the violation of CPT invariance in an interacting RQFT entails the violation of Lorentz invariance. This claim is surprising since standard proofs of the CPT theorem require more assumptions than Lorentz invariance, and are restricted to non-interacting, or at best, unrealistic interacting theories. This essay analyzes this claim in the context of the debate between pragmatist approaches to RQFTs, which trade mathematical rigor for the ability to derive predictions from realistic interacting theories, and purist approaches, which trade the ability to formulate realistic interacting theories for mathematical rigor.

In this essay, I examine the curved spacetime formulation of Newtonian gravity known as Newton–Cartan gravity and compare it with flat spacetime formulations. Two versions of Newton–Cartan gravity can be identified in the physics literature—a “weak” version and a “strong” version. The strong version has a constrained Hamiltonian formulation and consequently a well-defined gauge structure, whereas the weak version does not (with some qualifications). Moreover, the strong version is best compared with the structure of what Earman (World enough and spacetime. Cambridge: MIT Press) has dubbed Maxwellian spacetime. This suggests that there are also two versions of Newtonian gravity in flat spacetime—a “weak” version in Maxwellian spacetime, and a “strong” version in Neo-Newtonian spacetime. I conclude by indicating how these alternative formulations of Newtonian gravity impact the notion of empirical indistinguishability and the debate over scientific realism.

Einstein algebras have been suggested (Earman 1989) and rejected (Rynasiewicz 1992) as a way to avoid the hole argument against spacetime substantivalism. In this article, I debate their merits and faults. In particular, I suggest that a gauge-invariant interpretation of Einstein algebras that avoids the hole argument can be associated with one approach to quantizing gravity, and, for this reason, is at least as well motivated as sophisticated substantivalist and relationalist interpretations of the standard tensor formalism.

To describe the development of a pharmacy driven off-label recombinant factor seven (rFVIIa) protocol by a multi-disciplinary team for critical bleeding. A multi-disciplinary team made up of members from several critical care and surgical departments within the hospital were formed and charged with developing a standardized approach to how rFVIIa would be used for critical bleeding in an academic medical center. Groups represented on the multi-disciplinary team included clinical pharmacy, emergency medicine, pulmonary, hematology, cardiothoracic surgery, trauma, neurosurgery, and vascular surgery physicians. A pharmacist driven off-label rFVIIa protocol was developed and implemented for the use in those patients with critical bleeding. The protocol was based on the available literature and local expert opinion. Through the use of this protocol a significantly smaller average dose of rFVIIa is now being used when compared to those patients treated prior to the new protocol (47.5 vs. 62.2 mcg/kg, p = 0.036) while all-cause mortality was not significantly altered (35 vs. 48.8 %, p = 0.057). An effective and safe pharmacy driven protocol was implemented by a multi-disciplinary team for rFVIIa as seen by providing a significantly lower average dose of rFVIIa while not sacrificing for overall patient mortality.

In recent articles, Zangari (1994) and Karakostas (1997) observe that while an e-extended version of the proper orthochronous Lorentz group O↑+ (1,3) exists for values of e not equal to zero, no similar e-extended version of its double covering group SL(2, C) exists (where e=1−2eR, with eR the non-standard simultaneity parameter of Reichenbach). Thus, they maintain, since SL(2, C) is essential in describing the rotational behaviour of half-integer spin fields, and since there is empirical evidence for such behaviour, e-coordinate transformations for any value of e≠0 are ruled out empirically. In this article, I make two observations: (a) There is an isomorphism between even-indexed 2-spinor fields and Minkowski world-tensors which can be exploited to obtain generally covariant expressions of such spinor fields. (b) There is a 2-1 isomorphism between odd-indexed 2-spinor fields and Minkowski world-tensors which can be exploited to obtain generally covariant expressions for such spinor fields up to a sign. Evidence that the components of such fields do take unique values is not decisive in favour of the realist in the debate over the conventionality of simultaneity in so far as such fields do not play a role in clock synchrony experiments in general, and determinations of the one-way speed of light in particular. I claim that these observations are made clear when one considers the coordinate-independent 2-spinor formalism. They are less evident if one restricts oneself to earlier coordinate-dependent formalisms. I end by distinguishing these conclusions from those drawn by the critique of Zangari given by Gunn and Vetharaniam (1995).

This essay touches on a number of topics in philosophy of quantum field theory from the point of view of the LSZ asymptotic approach to scattering theory. First, particle/field duality is seen to be a property of free field theory and not of interacting QFT. Second, it is demonstrated how LSZ side-steps the implications of Haag's theorem. Finally, a recent argument due to Redhead (1995), Malament (1996) and Arageorgis (1995) against the concept of localized particle states is addressed. Briefly, the argument observes that the Reeh-Schlieder theorem entails that correlations between spacelike separated vacuum expectation values of local field operators are always present, and this, according to the above authors, dictates against the notion of a localized particle state. I claim that this moral is excessive and that a coherent notion of localized particles is given by the LSZ approach. The underlying moral to be drawn from this analysis is that questions concerning the ontology of interacting QFT cannot be appropriately addressed if one restricts oneself to the free theory.

In this essay I examine a recent argument by Steven Weinberg that seeks to establish local quantum field theory as the only type of quantum theory in accord with the relevent evidence and satisfying two basic physical principles. I reconstruct the argument as a demonstrative induction and indicate it's role as a foil to the underdetermination argument in the debate over scientific realism.

This chapter reviews effective field theory (EFT) techniques, focusing on the intertheoretic relations between low-energy effective theories and their high-energy counterparts. It discusses how EFT can be interpreted and describes the steps in the construction of an EFT in the top-down and bottom-up approaches. The chapter also analyzes the dependence of EFT on renormalization schemes, and evaluates the extent to which the intertheoretic relation between an EFT and its high-energy theory can be described in terms of emergence.

Relativistic quantum field theories (RQFTs) are invariant under the action of the Poincare group, the symmetry group of Minkowski spacetime. Non-relativistic quantum field theories (NQFTs) are invariant under the action of the symmetry group of a classical spacetime; i.e., a spacetime that minimally admits absolute spatial and temporal metrics. This essay is concerned with cashing out two implications of this basic difference. First, under a Received View, RQFTs do not admit particle interpretations. I will argue that the concept of particle that informs this view is motivated by non-relativistic intuitions associated with the structure of classical spacetimes, and hence should be abandoned. Second, the relations between RQFTs and NQFTs also suggest that routes to quantum gravity are more varied than is typically acknowledged. The second half of this essay is concerned with mapping out some of this conceptual space.

This essay considers the prospects of modeling spacetime as a phenomenon that emerges in the low-energy limit of a quantum liquid. It evaluates three examples of spacetime analogues in condensed matter systems that have appeared in the recent physics literature, indicating the extent to which they are viable, and considers what they suggest about the nature of spacetime.

In this essay, I consider the ontological status of spacetime from the points of view of the standard tensor formalism and three alternatives: twistor theory, Einstein algebras, and geometric algebra. I briefly review how classical field theories can be formulated in each of these formalisms, and indicate how this suggests a structural realist interpretation of spacetime.