Lecture Abstracts

Larissa Albantakis (Wisconsin-Madison): Integrated Information Theory of Consciousness: Introduction, Tutorial, and Extrapolations

Abstract: The Integrated Information theory of consciousness (IIT) has recently attracted attention among consciousness researchers. IIT stems from thought experiments that lead to phenomenological axioms and ontological postulates (intrinsic existence, composition, information, integration, and exclusion). According to IIT, an experience is a maximally integrated cause-effect structure, which in principle can be completely characterized, both in quantity and quality, by determining to what extent a system of causal mechanisms is irreducible to its parts. Many observations concerning the neural substrate of consciousness fall naturally into place within the IIT framework. Among them are the association of consciousness with certain neural systems rather than with others; the fact that neural processes underlying consciousness can influence or be influenced by neural processes that remain unconscious; the reduction of consciousness during dreamless sleep and generalized epileptic seizures; and the distinct role of different cortical architectures in affecting the quality of experience. The lecture will i) introduce the basic notions of IIT, and provide hands-on examples in which integrated information can be computed rigorously; ii) introduce measures of integrated information that can be applied to empirical data and discuss how they can be applied to evaluate the level of consciousness in wake, sleep, anesthesia, and disorders of consciousness; iii) demonstrate how integrated information grows in animats adapting to a complex environment, thereby shedding light on the evolution of consciousness; iv) consider the explanatory, predictive, and inferential power of IIT; and v) consider potential problems and future developments.

Dave Baker (Michigan):

1: Supersymmetric QFT

Abstract:  Supersymmetry in quantum physics is a mathematically simple phenomenon that raises deep foundational questions. To motivate these questions, I present a toy model, the supersymmetric harmonic oscillator, and its superspace representation, which adds extra anticommuting dimensions to spacetime. I then explain and comment on three foundational questions about this superspace formalism: whether superspace is a substance, whether it should count as spatiotemporal, and whether it is a necessary postulate if one wants to use the theory to unify bosons and fermions.

Suggested Reading: Draft at https://bit.ly/2KI5PlY (please don’t circulate or cite)

2: Worldsheet relationism for string theory (based on joint work with Noel Swanson)

Abstract: The two-dimensional worldsheet is the string-theoretic analogue of a particle’s worldline.  Some string theorists have speculated that the worldsheet may be the fundamental spacetime geometry of our world, from which familiar four-dimensional spacetime emerges.  We will consider  possible ontologies for this worldsheet geometry, and speculate about whether the string theory program is likely to converge on a fundamental theory compatible with these worldsheet ontologies.
Suggested Readings:

• Laurent Freidel (Perimeter): TBA

• Gerald Gabrielse (Northwestern): TBA

Andrew Hearin (Argonne National Laboratory): Simulated Knowledge: Cosmological inference with numerical simulations of the universe

Abstract: Cosmology is one of the most rapidly evolving areas of modern science. Over the past three decades, cosmology has been transformed from a largely theoretical discipline into a field seeking precise, quantitative answers to questions about the universe’s origin, its contents, and its ultimate fate. This transformation has been brought about primarily by advances in observational astronomy, such as high-precision measurements of the cosmic microwave background, and the collection of enormous volumes of high-quality galaxy images and spectra. Recently, however, breakthroughs in cosmology are increasingly driven by supercomputers, particularly by our improving ability to simulate the formation and evolution of galaxies and the dark matter halos they inhabit. In this talk, I will review the contemporary “standard model” of cosmology, giving special attention to the field’s recent shift towards simulation-derived results. I will conclude by posing an open question: Are cosmological simulations and machine-learning algorithms simply the modern face of theoretical physics? Or have cosmologists made a devil’s bargain that has changed the nature of empirical inference itself?

Don Howard (Notre Dame): How General Relativity Shaped Twentieth-Century Philosophy of Science

Abstract: To this day it is still too little appreciated that general relativity had a major impact on the fine-structure of twentieth-century philosophy of science, especially within the logical empiricist tradition, both in setting the problematic agenda and in defining the major alternative points of view on core issues. This talk aims to tell the story of how that happened. More specifically, we will look at three clusters of issues: 1. The logical structure and empirical interpretation of physical theory; 2. The ontology of physical theory; 3. The heuristics of scientific discovery. We will do this by pursuing two different narrative lines: (a) Point coincidences, “Eindeutigkeit,” and the ontological commitments and empirical interpretation of general relativity, and (b) Neo-Kantianism, Conventionalism, and the “New Empiricism.” These two narrative lines have a common point of origin in late 1915, diverge somewhat during that latter 1910s, and then reconverge in the early 1920s at the time when the problematic landscape of mature logical empiricism was set in the form that dominated discourse into that latter half of the century. Along the way, I also want to emphasize the point that Einstein, especially, was uncommonly sophisticated about the relevant philosophical issues, just as his principal philosophical interlocutors were uncommonly sophisticated about the physics.
Suggested Reading: https://bit.ly/2KI5PlY

• Nick Huggett (UIC): From Strings to Spacetime

Abstract: The first half of this lecture will discuss the basic framework of string theory, while the second will discuss and evaluate meaning of the derivation of general relativity – particularly for the status of geometry and its relation to matter.

Suggested Readings: https://bit.ly/2KI5PlY

• Kerry McKenzie (UCSD):

Metaphysics is often characterized as being centrally concerned with the fundamental.  In these lectures, we consider what metaphysical implications might be embedded in contemporary physicists’ operative concept of fundamentality.  Our focus will be on quantum field theory and specifically the Coleman-Gross theorem – a theorem that places quite stringent constraints on the matter content of a fundamental quantum field theory.  Throughout we will consider the question of what aspects, if any, of our conclusions may be expected to hold in future physics, and the implications of theory-change for the proper expression of ‘naturalistic metaphysics’.  

1. QFT and Fundamentality Metaphysics: Humeanism and Structuralism

Abstract: In this lecture we will briefly consider some reasons why metaphysics is thought to concern the fundamental in particular, and some reasons why metaphysicians should care about physics when theorizing about it. The Coleman-Gross theorem will then be presented, together with an intuitive justification for why it holds. We will then consider two arguments to the effect that this theorem has a transformative effect on metaphysics.  The first is the claim that it presages a Humean-friendly form of necessitarianism.  The second is the claim that it vindicates the thesis of ontic structural realism.  We will then identify the criticisms that could be made to these arguments, on both ‘internal’ grounds and – looking forward to the afternoon session – on the grounds that QFT is not a truly fundamental framework for physics.

2. QFT and Fundamentality Metaphysics: Explaining the fundamental.

Abstract: In this lecture we will revisit the Coleman-Gross theorem and consider what it might have to tell us about how fundamentality itself ought to be conceived of in metaphysics.  We will consider in particular whether the fundamental ought to be regarded as by definition ‘brute and inexplicable’, or rather whether physicists can hope to achieve their goal of explaining everything – the fundamental included. 

• Tom Pashby (Chicago): Experience, Evolution and Observers in Quantum Mechanics

Abstract: The early expectations of Bohr and Heisenberg were that the observer must reside outside the representation of the quantum state of a system since (roughly) our experience of the world is classical.  According to Stein, the failure to represent ourselves within a physical theory presents an epistemological problem.  Recent interpreters of quantum mechanics either deny or attempt to resolve this problem in various ways.  In this talk, my focus is on the use of evolutionary and functionalist arguments by Everettians to justify the seeming contradiction between the definite world of experience and the superposed states predicted by unitary quantum evolution.  In particular, I examine Saunders’ use of evolutionary arguments in the context of a consistent histories interpretation (in line with Gell-Mann and Hartle’s consideration of observers as Information Gathering and Utilizing Systems) and Wallace’s functionalist argument that a quantum measurement multiplies observers as well as relative states. I conclude by examining a more recent proposal of Zurek that applies Darwinian arguments at the level of primitive quantum states, which (I argue) suggests a possible reapproachment between ontological and epistemological approaches to the quantum state.
Suggested readings:
Stein (1994) Some Reflections on the Structure of Our Knowledge in Physics (http://strangebeautiful.com/other-texts/stein-reflections-struct-knowledge-physics.pdf)
Saunders (1993) Decoherence, Relative States and Evolutionary Adaptation (https://bit.ly/2KI5PlY)
Wallace (2003) Everett and Structure (https://arxiv.org/pdf/quant-ph/0107144v2.pdf)
Zurek (2009) Quantum Darwinism (https://arxiv.org/pdf/0903.5082.pdf)

• Lee Smolin (Perimeter): Principles for quantum gravity

Abstract:  I discuss several proposed principles we might expect a quantum theory of gravity to satisfy, including background independence, the fundamental role of causality, and appropriate versions of the holographic principle and the equivalence principle, both suitably modified.   I argue that a test a proposed set of principles should satisfy is to allow the derivation of general relativity as a classical limit, directly from the principles.
Suggested readings:

• Nic Teh (Notre Dame): Heterodox observables and the conventionality of quantum geometry

Abstract: I will describe how philosophical reflection on the program of PT-symmetric quantum theory leads us to a better understanding of non-standard or “heterodox” quantum observables. This in turn leads to a natural analogy between such heterodox representational schemes and the the “spacetime conventionalism” that is demonstrated by non-standard relativistic theories of gravity such as teleparallel gravity. If time permits, I will also explain how it leads to some interesting new structures in the categorical approach to quantum observables.