
Publications
2017.

'Topological
Order and Emergence'
Topologically
ordered systems play a prominent role in
current research in condensed matter physics
(examples include integer
and fractional
quantum Hall systems, topological
insulators, and topological
superconductors). These systems cannot
be characterized by the standard LandauGinsburg
theory of phase transitions that has informed much
of the discussion, in both the physics and the
philosophical literature, of emergence in
condensed matter systems. Nevertheless many
authors claim topologically ordered systems
exhibit emergence. This essay tries to make
sense of these claims.

2016.

'Emergence and
Mechanism in the Fractional Quantum Hall Effect'
A fractional
quantum Hall (FQH) system can be described
in at least four distinct ways: (i) as a
system of strongly coupled electrons in the
presence of an external magnetic field; (ii) as a
system of weakly coupled composite fermions
(electrons with an even number of attached
magnetic fluxes) in the presence of a modified
external magnetic field; (iii) as a system of
composite bosons (electrons with an odd number of
attached magnetic fluxes) in the absence of an
external magnetic field; or even (iv) as a system
of strongly correlated electrons in "longrange
entangled" states. These alternative
formulations can be viewed as providing the bases
of four distinct mechanistic explanations of the
FQH effect. Now many authors have claimed
that FQH systems exhibit emergence. Taking
them seriously, it seems to me, makes trouble for
"mechanismcentric" accounts of emergence that
require the specification of a unique causal
mechanism. My preference is for a
"lawcentric" account of emergence in which novel
emergent behavior is underwritten by distinct,
dynamically robust laws (as opposed to causal
mechanisms). I think such a "lawcentric"
account of emergence does just fine in explainging
emergent behavior associated with the FQH effect.

2015.

'Pragmatists and Purists
on CPT Invariance in RQFTs'
Greenberg
(2002) claims 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
noninteracting, or at best, unrealistic
interacting theories. This essay analyzes
Greenberg's 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.

2014.

'Three Principles of
Quantum Gravity in the Condensed Matter Approach'
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
identity 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.

2013e.

'Emergence in
Effective Field Theories'
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
highenergy 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.

2013d.

'CPT Invariance, the
SpinStatistics Connection, and the Ontology of
RQFTs'
CPT
invariance and the spinstatistics
connection are typically taken to be essential
properties in relativistic quantum field
theories (RQFTs), insofar as the CPT and
SpinStatistics theorems entail that any state
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
SpinStatistics theorems suggest about the
ontology of RQFTs, and the extent to which this is
compatible with the Received View.

2013c.

'The Emergence of
Spacetime in Condensed Matter Approaches to
Quantum Gravity'
Condensed matter approaches to
quantum gravity suggest that spacetime emerges in
the lowenergy sector of a fundamental
condensate. This essay investigates what
could be meant by this claim. In particular,
I offer an account of lowenergy 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 sysrtems of the type that are relevant to
quantum gravity.

2013b.

'CategoryTheoretic
Structure and Radical Ontic Structural Realism'
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 settheoretic formulation of structure, and that
adopting a categorytheoretic
formulation may provide ROSR with more
support. In particular, I consider how a
categorytheoretic formulation of structure can be
developed that denies (ii), and can be made to do
work in the context of formulating theories in
physics.

2013a.

'Effective Field Theory'
An effective
field theory (EFT) of a physical system is a
theory of the dynamics of the system at energies
small compared to a given cutoff. For some
systems, lowenergy states with respect to this
cutoff are effectively independent of ("decoupled
from") states at high energies. Hence you
can study the lowenergy sector fo the theory
without the need for a detailed description of the
highenergy sector (this makes calculations
easier, plus you don't have to worry about thorny
issues like renormalizability). Many
physicists currently think that the Standard Model
of particle physics is an example of an EFT of an,
as yet, unknown highenergy theory. This
essay is a general review of EFTs; in particular,
it identifies two conceptually distinct types
("Wilsonian" and "continuum"), and considers how
they might be interpreted, and alos what they say
(and do not say) about the notion of emergence.

2011.

'QFTs in
Classical Spacetimes and Particles'
According to a Received View among
philosophers, 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 total number
operators. Various results (the ReehSchlieder
theorem, the Unruh
Effect, Haag's
theorem) then indicate that formulations of
RQFTs do not support such operators. These
mathematical results, however, don't hold for
nonrelativistic QFTs (NQFTs). I point out
that this is due to the absolute temporal
structure of the classical spacetimes associated
with NQFTs. This seems to suggest that the
choices that the Received View makes in
mathematically representing its intuitions about
the nature of particles are (implicitly) informed
by nonrelativistic intuitions.

2010.

'Relativity and
Quantum Field Theory'
Relativistic quantum field theories
(RQFTs) are invariant under the action of the
symmetry group of a Lorentzian spacetimea
spacetime that admits a Lorentzian (i.e.
"relativistic") metric. Nonrelativistic
quantum field theories (NQFTs) are invariant under
the action of a symmetry group of a classical
spacetimea spacetime that minimally admits
separate absolute spatial and temporal
metrics. This essay is concerned with
cashing out two impliciations of this basic
difference. First, it suggests that a
Received View that claims RQFTs cannot support
particle interpretations is perhaps implicitly
biased with nonrelativistic intuitions (this is
argued for in more detail in 2011). Second,
the relations between RQFTs and NQFTs also suggest
that routes to quantum gravity are more varied
than is typically acknowledged. In
particular, they suggest it should be conceptually
possible to construct a quantum theory of gravity
by taking the "thermodynamic limit" of a
relativistic "particle" (i.e. finite degrees of
freedom) theory of gravity (although I have no
idea how this might be made more precise).

2008.

'Condensed Matter
Physics and the Nature of Spacetime'
Some condensed matter systems
exhibit lowenergy behavior that can be described
by effective field theories that are formally
similar to field theories that appear in other
areas of physics. The "acoustic" spacetime
research programme, for instance, is based on
modeling general relativity by teh lowenergy
behavior of superfluid Helium 4 (and similar
systems). Aspects of the Standard Model of
particle physics can be modeled by the lowenergy
behavior of superfluid Helium 3A, and aspects of
conformal field theories (for which twistors
come in handy) can be modeled by the lowenergy
behavior of the edge of 4dim quantum Hall
liquids. This paper evaluates such examples
and considers what they have to tell us about the
nature of spacetime; in particular, how they might
impact the debate between substantivalists and
relationalists.

2006.

'Spacetime
Structuralism'
This paper goes hogwild with a
number of different mathematical formalisms (twistors,
Einstein algebras, geometric
algebra) that can be used to formulate
classical field theories. The point is to
indicate that if you're predisposed to read
ontology off of your formalism, then you'd be
advised to dig deep and go for some notion of
structure, seeing as how alternative formalisms
can be very different beasts, indeed.

2004.

'Theories of
Newtonian Gravity and Empirical
Indistinguishability'
There's not just one, but many theories
of Newtonian gravity. Some are in flat
spactimes, others are in curved spacetimes.
Are they really different theories, or just
different ways of formulating the same basic
theory? Inquiring minds want to know...

2003.

'Einstein Algebras and
the Hole Argument'
Einstein algebras are abstract
algebras that encode the essential structure
associated with general relativity (GR).
They've been suggested, and rejected, as a way to
avoid the Infamous Hole
Argument against one way of interpreting
GR. This paper points out that some
physicists are trying to use them to construct
theories of quantum gravity, and that this gives
them a bit more respectability than they've
typically been afforded.

2001.

'What Should
Philosophers of Science Learn from the History of
the Electron?' (with John Norton)
That it's structure that's retained
across theory change, and that structure is kinda
hard to define in a precise way (although we do
make an effort).

2000b.

'The
CoordinateIndependent 2Component Spinor
Formalism and the Conventionality of Simultaneity'
Some philosophers of spacetime have
claimed that the structure associated with
halfintegerspin (fermionic) fields can settle
the debate over the conventionality
of simultaneity. This paper disputes
this claim, in particular by calling attention to
how fermionic fields can be represented in a
manifestly coordinateindependent way.

2000a.

'Against Particle/Field
Duality: Asymptotic Particle States and
Interpolating Fields in Interacting QFT (or:
Who's Afraid of Haag's Theorem?)'
This paper tries to indicate how the
LSZ formalism that's used by practicing physicists
suggests ways of interpreting fuzzy concepts like
"particle" and "localization" in quantum field
theory (as well as dealing with Haag's
theorem). And that these ways are to
be preferred to the ways suggested by more
abstract (and expressively incomplete) formalisms
(like the algebraic formalism).

1999.

'Weinberg on QFT:
Demonstrative Induction and Underdetermination'
This paper reviews an argument by
Steven Weinberg that seeks to establish a
particular formulation of quantum field theory as
the only type of quantum theory in accord with the
relevant evidence and satisfying two basic
physical principles. The paper reconstructs
Weinberg's argument as a demonstrative induction
and indicates it's role as a (potential) foil to
the underdetermination argument in the debate over
scientific realism.

1998.

'Whitehead's Theory of
Gravity'
Everything you ever wanted to know
about Whitehead's theory of gravity...

Drafts
Frontburner
1.

'Holographic Spacetime and
Quantum Error Correction Codes', in preparation.
This essay seeks to understand
recent proposals that link aspects of the AdS/CFT
correspondence with
quantum error correction codes
(QECCs). The AdS/CFT correspondence is a
dictionary that relates aspects of a (d+1)dim
"bulk" gravitational theory to a ddim
"boundary" quantum field theory. One
apparent problem with this dictionary is called
the "bulk locality paradox": A standard way
of representing a bulk field in terms of boundary
fields (the AdSRindler representation) seems to
entail that any given boundary field must be a
multiple of the identity. This is very
similar to a necessary and sufficient condition
for QECCs, and this has motivated some
authors to suggest we view the bulk theory
as a code subspace that protects quantum
information in the boundary from erasure.
What in the world could this mean?

2.

'Why Be Natural?',
in submission.
Only because naturalness
underwrites a nontrivial notion of emergence for
effective quantum field theories (and, arguably,
not because it's empirically warranted, or
quantifiable, or underwrites a central dogma of
effective field theories)...

3.

'NonLocality in
Instrinsic Topologically Ordered Systems', in
submission.
Intrinsic
topologically ordered (ITO) condensed matter
systems are claimed to exhibit two types of
nonlocality: one type associated with
topological properties, and the other associated
with quantum entanglement. This is supposed
to allow ITO systems to encode information in the
form of quantum entangled states in a
topologically nonlocal way that protects it
against local errors. This is a Big Deal,
since it would make possible topological quantum
computation. But topological nonlocality is
very different conceptually from quantum
entanglement nonlocality. Is the Big Deal
based on a misunderstanding of these two senses of
nonlocality? Mathematicians
seem to realize the importance of the distinction,
but it's unclear if condensed matter physicists
do, too.

4.

'What Explains the
SpinStatistics Connection?', draft.
The spinstatistics
connection plays an essential role in
explanations of nonrelativistic phenomena
associated with both fieldtheorertic and
nonfieldtheoretic systems (for instance, it
explains the electronic structure of solids and
the behavior of EinsteinBose condensates and
superconductors). However, it is only
derivable within the context of relativistic
quantum field theory (RQFT) in the form of the
SpinStatistics theorem; and moreover, there are
multiple, mutually incompatible ways of deriving
this theorem. This essay attempts to
determine the sense in which the spinstatistics
connection can be said to be an essential property
in RQFT, and how it is that an essential property
of one type of theory can figure into fundamental
explanations offered by other, inherently distinct
theories.

Backburner
