Foil 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.
Format results


Compatibility of implicit and explicit observers in quantum theory and beyond
Institute for Quantum Optics and Quantum Information (IQOQI)  ViennaPIRSA:18040084 
From observers to physics via algorithmic information theory I
Institute for Quantum Optics and Quantum Information (IQOQI)  ViennaPIRSA:18040078 
From observers to physics via algorithmic information theory II
Institute for Quantum Optics and Quantum Information (IQOQI)  ViennaPIRSA:18040080 
Motility of the internalexternal cut as a foundational principle
Perimeter Institute for Theoretical PhysicsPIRSA:18040073 




Agents, Subsystems, and the Conservation of Information
University of Hong Kong (HKU)PIRSA:18040089 