Zenith Grant Awardee

Richard Easther

University of Auckland

Co-Investigators

Eugene Lim, Kings College London

Project Title

Minimal Observers and Maximal Observations

Project Summary

This project seeks to understand the simplest imaginable observers that can exist, and the most complex possible observations observers may perform. Many models of fundamental physics suggest that our universe is embedded in a much larger multiverse. Paradoxically, while the idea of the multiverse emerges from science but we may never be able to test it scientifically. Any single observer (or group of observers able to communicate with one another) sees one only universe so the overall multiverse is not, by definition, observable. Moreover, the laws of physics may be different within each universe so many universes may be insufficiently complex to host observers — not only can we can only observe a single universe, our sample is biased since we must be able to exist within it. We will tackle this problem by investigating the minimal level of complexity needed to support cyclic, autocatalytic chemical reactions, pathways apparently critical to abiogenesis or the origin of life, establishing a lower bound on the level of complexity that permits observers to exist. Separately, we will extend well-tested cosmological statistical methods to permit well-posed probabilistic assessments of specific multiverse proposals by observers living inside a single universe.

Technical Abstract

The cosmological observer is central role to discussions of particle physics and the global configuration of the universe. In particular, cosmological observers are key to multiverse proposals, as the distinction between a universe and the multiverse is ultimately a consequence of single observers being limited to accessing a finite volume of spacetime. This project will carefully analyze \"maximal observations\", which allow individual observers to draw sound inferences about the existence of the multiverse. We will approach this problem using Bayesian Networks, and elucidate the extent to the intrinsic uncertainties in observational inferences about the multiverse can be viewed as an extreme form of cosmic variance. Separately, we will look carefully at \"minimal observers\", focusing on identifying the smallest possible set of interactions and particles that can give rise to sets autocatalytic reactions, such as well-known Brusselator system. We postulate that the existence of such systems is a necessary condition for abiogenesis and the formation of observers. Our goal is to quantify the extent to which anthropic arguments constrain the form of the fundamental interactions in ways that avoid more abstract questions regarding the fundamental nature of the observers themselves.