Bell's theorem and the measurement problem: reducing two mysteries to one?

TL;DR

This paper explores how revising classical causation notions can reconcile quantum theory with relativity, linking the measurement problem to Bell's theorem and suggesting causation is an emergent phenomenon.

Contribution

It proposes that resolving the conflict between quantum theory and relativity involves understanding causation as emergent and connecting it to the measurement problem.

Findings

Reformulation of Bell's theorem from causal principles.

Quantum causation theories often rely on agent-centric notions.

Resolving quantum-relativity conflict may require solving the measurement problem.

Abstract

In light of a recent reformulation of Bell's theorem from causal principles by Howard Wiseman and the author, I argue that the conflict between quantum theory and relativity brought up by Bell's work can be softened by a revision of our classical notions of causation. I review some recent proposals for a quantum theory of causation that make great strides towards that end, but highlight a property that is shared by all those theories that would not have satisfied Bell's realist inclinations. They require (implicitly or explicitly) agent-centric notions such as "controllables" and "uncontrollables", or "observed" and "unobserved". Thus they relieve the tensions around Bell's theorem by highlighting an issue more often associated with another deep conceptual issue in quantum theory: the measurement problem. Rather than rejecting those terms, however, I argue that we should understand why they seem to be, at least at face-value, needed in order to reach compatibility between quantum theory and relativity. This seems to suggest that causation, and thus causal structure, are emergent phenomena, and lends support to the idea that a resolution of the conflict between quantum theory and relativity necessitates a solution to the measurement problem.