Ghislain Fourny will give an invited talk at VISCON 2023

Ghislain Fourny will give an invited talk on "Einstein, determinism, and quantum theory" on 21 October at VISCON 2023 in Zurich.

Abstract:

Albert Einstein is famous for many things, including for advocating that quantum theory is an incomplete description of reality that can be extended to a more powerful theory -- involving local realism and hidden variables. Today, the mainstream opinion is that he was wrong. And yet, in this talk, I will explain why I think he was right, to the point of having already committed almost 20 years of my life working on this. I will describe the impact that him being right would have on our definition of free choice, and show what an extension theory with more predictive power could look like.

We will start the presentation with a basic coverage of locality, realism, determinism, probabilities, and what it fundamentally means to do science and to try to understand our universe better. We will also look into the Bell inequalities and how they drastically limit the ways that quantum theory can be extended while preserving Einsteinian locality (cause and effects cannot propagate faster than light).

Then, we will move on to a discussion of what free choice means, but from a purely mathematical perspective. Free choice is a fundamental concept in the quantum foundations, because the (free) choice of experiments we conduct to better understand nature plays a fundamental role in (perceived) quantum randomness. We will in particular discuss and differentiate between causation, correlations, and counterfactuals.

Then, based on this distinction, we will dive into a proposed extension of spacetime called space-time-hap manifolds that I built on top of the work of De Broglie (1920s) and Bohm (1950s), where the hap (for happenstance) coordinates model our location across parallel worlds (similar to the Sliders series), in complement to "where" and "when".

We will see that, at the macroscopic level, parallel worlds have a tree-like structure with a fork at each decision point (measurement basis, measurement outcome), which allows us to replace the mainstream probabilistic view of quantum physics with a game-theoretical approach in which Nature is an action-minimizing economic agent. We will explain why impossibility theorems imply that the suchly obtained models cannot be solved with Nash equilibria. We will quickly discuss a non-Nashian approach that involves a weaker definition of free choice, is more computationally efficient, and only reaches Pareto-optimal outcomes.