Format results

1 talkCollection Number C18008
Talk

Scattering Amplitudes, String Models and Gravitational Waves
Ricardo Monteiro Queen Mary  University of London (QMUL)


Algorithmic Information, Induction and Observers in Physics
17 talksCollection Number C18007Talk


Quantum speedup in testing causal hypotheses
Giulio Chiribella The University of Hong Kong (HKU)

The Logic of Physical Law
Stefan Wolf Universit della Svizzera italiana


On the concepts of universality in physics and computer science
Gemma De Las Cuevas Universität Innsbruck

A nogo theorem for observerindependent facts
Časlav Brukner Vienna Center for Quantum Science and Technology


Algorithmic information theory: a critical perspective
Tom Sterkenburg LudwigMaximiliansUniversitiät München (LMU)


Observers in Quantum and Foil Theories
11 talksCollection Number C18006Talk

Wavefunction branches as a foundation for constructing foil theories
Jess Riedel NTT Research
PIRSA:18040082 
Compatibility of implicit and explicit observers in quantum theory and beyond
Thomas Galley Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna
PIRSA:18040084 
From observers to physics via algorithmic information theory I
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna
PIRSA:18040078 
From observers to physics via algorithmic information theory II
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna
PIRSA:18040080 
Motility of the internalexternal cut as a foundational principle
Robert Spekkens Perimeter Institute for Theoretical Physics
PIRSA:18040073 

Quantum theory cannot consistently describe the use of itself
Renato Renner ETH Zurich
PIRSA:18040085 


Open Research: Rethinking Scientific Collaboration
11 talksCollection Number C18005Talk


Data Mists, Blockchain Republics, and the Moon Shot
Simon DeDeo Indiana University

Like penguins on an ice floe: The scary business of adopting open science practices
Benedikt Fecher Alexander von HumboldtStiftung

Collaborative Knowledge Ratchets and Fermat's Library

Jess Riedel NTT Research

Luis Batalha Fermat's Library
PIRSA:18030101 


What’s not to like? Open science will fail unless it takes the costs seriously
Rosie Redfield University of British Columbia




Gauge Theory, Geometric Langlands and Vertex Operator Algebras
11 talksCollection Number C18004Talk

Gauge Theory, Geometric Langlands, and All That
Edward Witten Institute for Advanced Study (IAS)  School of Natural Sciences (SNS)

Overview of the global Langlands correspondence
Dima Arinkin University of Wisconsin–Milwaukee

Gauge theory, vertex algebras and quantum Geometric Langland dualities
Davide Gaiotto Perimeter Institute for Theoretical Physics


Introduction to local geometric Langlands
Sam Raskin The University of Texas at Austin





Computational Methods for General Relativistic Magnetohydrodynamics: con2prim an
Collection Number C18001 
The Path Integral for Gravity
18 talksCollection Number C17057Talk

Welcome and Opening Remarks
Neil Turok University of Edinburgh

The significance of the proper time in the quantum mechanics of the gravitational field.
Claudio Bunster Centro de Estudios Científicos (CECs)

TBA
Viatcheslav Mukhanov LudwigMaximiliansUniversitiät München (LMU)

Semiclassical evaluation of the 3D gravity path integral and quasilocal holography
Bianca Dittrich Perimeter Institute for Theoretical Physics


An asymptotically safe point of view on the gravitational path integral
Astrid Eichhorn University of Southern Denmark

The path integral for gravity and Fedosov quantization
Stefan Hollands Universität Leipzig

Surprises in the Path Integral for Gravity
Neil Turok University of Edinburgh


Quantum Black Holes in the Sky?
34 talksCollection Number C17055Talk

Quantifying the evidence for black holes with GW and EM probes
Paolo Pani Instituto Superior Tecnico  Departamento de Física

Echoes from the Abyss: Tentative Evidence for PlanckScale Structure at Black Hole Horizons
Jahed Abedi University of Stavanger (UiS)

Improvements on the methods for searching echoes
Julian Westerweck Albert Einstein Institute

A modelindependent search for gravitationalwave echoes
Archisman Ghosh Institucio Catalana de Recerca I Estudis Avancats (ICREA)  Universitat de Barcelona

An alternative significance estimation for the evidence for echoes
Alex Nielsen Albert Einstein Institute


Inspiral Tests of Strongfield Gravity and Ringdown Tests of Quantum Black Holes
Kent Yagi University of Virginia

A Recipe for Echoes
Aaron Zimmerman The University of Texas at Austin


Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062 
HandsOn Maple Workshop
Collection Number C17061 
Experimental techniques in tabletop fundamental physics
24 talksCollection Number C17030Talk

Welcome and Opening Remarks
Asimina Arvanitaki Perimeter Institute for Theoretical Physics

Theory Talk
Asimina Arvanitaki Perimeter Institute for Theoretical Physics

A threedimensional optical lattice clock: precision at the 19th digit
Edward Marti University of Colorado Boulder

Measurement of the fine structure constant as a test of the standard model
Holger Mueller University of California, Berkeley

Superconducting accelerometer technology for precision tests of gravitation and search for new interactions
Ho Jung Paik University of Maryland, College Park

Searching for axions and new shortrange forces with resonant sensors
Andrew Geraci University of Nevada Reno

Testing Gravity at Extreme Scales
Giorgio Gratta Stanford University

Precision Physics in Storage Rings
Yannis Semertzidis Institute for Basic Science  Center for Axion and Precision Physics Research


Talk

Semisimple Hopf algebras and fusion categories
Cesar Galindo Universidad de los Andes

The Hopf C*algebraic quantum double models  symmetries beyond group theory
Andreas Bauer Freie Universität Berlin

Modular categories and the Witt group
Michael Mueger Radboud Universiteit Nijmegen

Topological Quantum Computation
Eric Rowell Texas A&M University

Gapped phases of matter vs. Topological field theories
Davide Gaiotto Perimeter Institute for Theoretical Physics

An Introduction to Hopf Algebra Gauge Theory
Derek Wise FriedrichAlexanderUniversität ErlangenNürnberg

Kitaev lattice models as a Hopf algebra gauge theory
Catherine Meusburger University of ErlangenNuremberg

Topological defects and highercategorical structures
Jurgen Fuchs Karlstad University


New Directions in Conventional and Ambitwistor String Theories
1 talkCollection Number C18008The goal of the workshop is to foster interaction between researchers working on the Smatrices of conventional strings and on ambitwistor strings. The workshop will exploit synergies between the two frameworks and identify the current key questions in the fields and areas that can benefit from collaboration. The program of the workshop will be tailored to questions and problems raised by the participants in the runup to the event. The goal is to spend most of the time on collaborative discussions in order to exchange expertise and to attempt to resolve questions during the workshop. A list of such problems can be found below and this will be extended by the participants in the runup to the meeting. To obtain ambitwistor integrands and BernCarrascoJohansson (BCJ) numerators for multiloop amplitudes and to connect with superstring worldsheet correlators. To develop fully nonlinear approaches by working on curved backgrounds both for application to AdS/CFT and to problems in perturbative gravity and gauge theory on nontrivial backgrounds. To understand the twistor and ambitwistor geometry underpinning both conventional and ambitwistor strings including the geometry of soft limits infrared structure and its links with formulations at null infinity. To explore mathematical structures behind the integrals of conventional and ambitwistor strings (positive geometries and canonical forms twisted (co)cycle etc.)

Algorithmic Information, Induction and Observers in Physics
17 talksCollection Number C18007Our universe is of astonishing simplicity: almost all physical observations can in principle be described by a few theories that have short mathematical descriptions. But there is a field of computer science which quantifies simplicity namely algorithmic information theory (AIT). In this workshop we will discuss emerging connections between AIT and physics some of which have recently shown up in fields like quantum information theory and thermodynamics. In particular AIT and physics share one goal: namely to predict future observations given previous data. In fact there exists a gold standard of prediction in AIT called Solomonoff induction which is also applied in artificial intelligence. This motivates us to look at a broader question: what is the role of induction in physics? For example can quantum states be understood as Bayesian states of belief? Can physics be understood as a computation in some sense? What is the role of the observer i.e. the agent that is supposed to perform the predictions? These and related topics will be discussed by a diverse group of researchers from different disciplines.

Observers in Quantum and Foil Theories
11 talksCollection Number C18006Foil theories sometimes called mathematically rigorous science fiction describe ways the world could have been were it not quantum mechanical. Our understanding of quantum theory has been deepened by contrasting it with these alternatives. So far observers in foil theories have only been modeled implicitly for example via the recorded probabilities of observing events. Even when multiagent settings are considered these agents tend to be compatible in the classical sense that they could always compare their observations. Scenarios where agents and their memories are themselves modeled as physical systems within the theory (and could in particular measure each other as in Wigner's friend experiment) have not yet been considered. In this workshop we will investigate which foil theories allow for the existence of explicit observers and whether they allow for paradoxes in multiagent settings such as those found in quantum theory. We will also investigate which interpretations of quantum theory would equally well interpret the foil theories and which interpretations are truly quantum. We will gain a deeper understanding of how this can happen by discussing appropriate definitions observers in these theories and seeing how such observers learn about their environment.

Open Research: Rethinking Scientific Collaboration
11 talksCollection Number C18005Scientific inquiry in the 21st century is beset with inefficiencies: a flood of papers not read theories not tested and experiments not repeated; a narrow research agenda driven by a handful of highimpact journals; a publishing industry that turns public funding into private profit; the exclusion of many scientists particularly in developing countries from cuttingedge research; and countless projects that are not completed for lack of skilled collaborators. These are all symptoms of a major communication bottleneck within the scientific community; the channels we rely on to share our ideas and findings especially peerreviewed journal articles and conference proceedings are inadequate to the scale and scope of modern science. The practice of open research doing science on a public platform that facilitates collaboration feedback and the spread of ideas addresses these concerns. Opensource science lowers barriers to entry catalyzing new discoveries. It fosters the realtime sharing of ideas across the globe favoring cooperative endeavor and complementarity of thought rather than wasteful competition. It reduces the influence of publishing monopolies enabling a new credit attribution model based on contributions made rather than references accrued. Overall it democratizes science while creating a new standard of prestige: quality of work instead of quantity of output. This workshop will bring together a diverse group of researchers from fields as diverse as physics biology computer science and sociology committed to opensource science. Together we will review the lessons learnt from various pioneering initiatives such as the Polymath project and Data for Democracy. We will discuss the opportunity to build a new tool similar to the software development platform GitHub to enable online collaborative science. We will consider the challenges associated with the adoption of such a tool by our peers and discuss ways to overcome them. Finally we will sketch a roadmap for the actual development of that tool.

Gauge Theory, Geometric Langlands and Vertex Operator Algebras
11 talksCollection Number C18004The workshop will explore the relation between boundary conditions in fourdimensional gauge theory the Geometric Langlands program and Vertex Operator Algebras.

Computational Methods for General Relativistic Magnetohydrodynamics: con2prim an
Collection Number C18001Computational Methods for General Relativistic Magnetohydrodynamics are important means of studying compact astrophysical objects such as neutron stars and corecollapse supernovae relevant e.g. to understand sources of gravitational radiation.Particular crucial elements of such methods including solving nonlinear equations to extract the microphysical state from the conserved fluxes (endearingly called con2prim) or handling realistic equations of state (EOS) that are only given approximately in a tabulated manner. The state of the art for algorithms addressing these issue leaves to be desired and significantly limits stabilityaccuracy and performance of todays calculations.This workshop aims to review the known algorithmic and computational shortcomings list requirements that an ideal solution should haveand discuss potential practical solutions.

The Path Integral for Gravity
18 talksCollection Number C17057Over the past three decades, the idea of a path integral over geometries, describing gravity in various dimensions, has become increasingly central to many areas of theoretical physics, including string and Mtheory, holography and quantum aspects of black holes and cosmology.
In each of these areas, the path integral is frequently invoked as a formal device although, as practitioners will admit, except in very special cases the basic formula remains undefined. Typically, classical saddle points are discussed, whether real or complex, but the required integrals are left unperformed.
This state of affairs is untenable because it leaves the theory on a shaky footing and hence does not permit a sound comparison of theoretical predictions with observations. The time has come to critically reassess the foundational ideas of the path integral for gravity, including its definition, evaluation and interpretation; to identify problems with
existing uses and claims based on it, and to seek improvements. The workshop will focus on the continuum theory and its semiclassical limit, with applications to cosmology, black holes and holography. In particular, the notion of a “Euclidean path integral” for a “wavefunction of the universe” will be addressed.To this effect we intend to revisit discussion of “quantum geometrodynamics” from the path integral viewpoint and to pursue various applications. The developments in this direction that took place in the late 1970's and early 1980's were not incorporated in subsequent efforts, where the emphasis shifted to using a classical background with quantum fluctuations superimposed on it, a split which although useful in particular approximations can hardly be imagined to lie at the foundation of the theory. The revival of the discussion of the foundation of the path integral for gravity is made timely, we believe, by the introduction of new global methods such as PicardLefschetz theory.
The format of the workshop will be unusual. For the first three days, the mornings will begin with a longer, introductory lecture by each of the three organisers, setting out some of the foundational issues. This will be followed by shorter lectures by the participants, tackling the same foundational questions. The morning lectures, held in the Bob room, will be open to all Perimeter residents and visitors. They will be recorded and made available for viewing on PIRSA. Afternoons will be devoted to friendly and informal discussions, with participants invited to offer short contributions which follow up or develop points raised in the mornings, within a relaxed and highly conducive environment. Participation in these afternoon discussion sessions, as well as social events associated with the workshop, will be limited to registered workshop participants. The last two days of the workshop will be an opportunity for participants to continue discussions on topics which emerge as of greatest general interest, as well as to follow up in smaller groups on technical points or new ideas.

Quantum Black Holes in the Sky?
34 talksCollection Number C17055The past decade has witnessed significant breakthroughs in understanding the quantum nature of black holes, with insights coming from quantum information theory, numerical relativity, and string theory. At the same time, astrophysical and gravitational wave observations can now provide an unprecedented window into the phenomenology of black hole horizons. This workshop seeks to bring together leading experts in these fields to explore new theoretical and observational opportunities and synergies that could improve our physical understanding of quantum black holes.

Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062With LIGO/VIRGO in operation and detecting gravitational waves, the era of gravitational wave astronomy is upon us. In anticipation of further observations, this workshop will discuss the physics, astrophysics, and observational prospectsas well as challengesin gravitational wave sources including black holes, neutron stars, and other fascinating objects, in both the near and long term.

HandsOn Maple Workshop
Collection Number C17061Generally speaking, physicists still experience that computing with paper and pencil is in most cases simpler than computing with a Computer Algebra System. Although that is true in some cases, the working paradigm is changing: developments in CAS, and particularly recent ones in the Maple system, have resulted in the implementation of most of the mathematical objects and mathematics used in theoretical physics computations, and have dramatically approximated the notation used in the computer to the one used with paper and pencil, diminishing the learning gap and computersyntax distraction to a strict minimum. In this talk, the Physics project at Maplesoft will be presented and the resulting Physics package will be illustrated through simple problems in classical field theory, quantum mechanics and general relativity, and through tackling the computations of some recent Physical Review papers in those areas. In addition to the 10:00 am lecture (taking place in Alice), there will be an afternoon handson workshop taking place from 2:00  5:00 pm in the Time Room.
We recommend that participants for the handson workshop bring their own laptop with a copy of Maple installed. Please contact Erik Schnetter <[email protected]> ahead of time if you cannot do this, and we will try to make other arrangements.
Registration for this event is now closed.

Experimental techniques in tabletop fundamental physics
24 talksCollection Number C17030In the last few years there has been a resurgence of interest in small scale high sensitivity experiments that look for new forces and new particles beyond the Standard Model. They promise to expand our understanding of the Cosmos and possibly explain mysteries such as Dark matter in a way that is complementary to colliders and other large scale experiments. There is a number of different physics motivations and approaches currently being explored in many ongoing and newly proposed experiments and they often share common experimental techniques.Many workshops in this field focus on the theory motivations behind these experiments without emphasis on the details of the experimental techniques that enable precision measurements. There is also substantial experimental expertise across many fields, often outside of fundamental physics community, that can be relevant to ongoing and proposed experiments.Thus, we decided to organize the workshop around some of the common experimental techniques. We hope it will be educational for both experimentalists and theorists and lead to discussions on the best way forward. We would like to bring together experimentalists with different expertise in the hope that it will lead to new ideas through interdisciplinary interactions. For theorists, we expect it to provide better appreciation of the challenges and opportunities in improving the sensitivity of precision measurement experiments.

Hopf Algebras in Kitaev's Quantum Double Models: Mathematical Connections from Gauge Theory to Topological Quantum Computing and Categorical Quantum Mechanics
18 talksCollection Number C17029The Kitaev quantum double models are a family of topologically ordered spin models originally proposed to exploit the novel condensed matter phenomenology of topological phases for faulttolerant quantum computation. Their physics is inherited from topological quantum field theories, while their underlying mathematical structure is based on a class of Hopf algebras. This structure is also seen across diverse fields of physics, and so allows connections to be made between the Kitaev models and topics as varied as quantum gauge theory and modified strong complementarity. This workshop will explore this shared mathematical structure and in so doing develop the connections between the fields of mathematical physics, quantum gravity, quantum information, condensed matter and quantum foundations.