Narratability and Cluster Decomposition

TL;DR

This paper challenges recent claims about non-narratability in relativistic quantum theories by linking it to violations of the cluster decomposition principle, a key locality condition.

Contribution

It demonstrates that non-narratability arises in systems that violate cluster decomposition, clarifying the conditions under which relativistic quantum theories can be narratable.

Findings

The examined system violates cluster decomposition.

Non-narratability correlates with violations of locality principles.

Many systems satisfying non-narratability also violate cluster decomposition.

Abstract

Recently David Albert presented an argument that relativistic quantum theories are non-narratable. That is, specifying the state on every space-like hypersurface in a given foliation of space-time is not in general sufficient to determine the states on other hypersurfaces, so the history of the universe cannot be told as a narration of states at successive times. We show that the system Albert examined to arrive at this conclusion violates cluster decomposition of the S-matrix, a locality requirement satisfied by relativistic quantum field theories. We formulate the general requirements for a system to display non-narratability, and argue that a large class of systems satisfying them violate the cluster decomposition principle.