Explanatory Strain and the Two-Slit Experiment: Introduction

The two-slit experiment is often described as the “central mystery” of quantum physics. Not because its experimental results are in doubt, but because explaining those results places extraordinary pressure on our ordinary ways of talking about systems, events, and causation. Where explanation strains, metaphor rushes in to compensate.

This short series takes as its point of departure a familiar passage from John Gribbin’s Six Impossible Things, in which single electrons passing through a two-slit apparatus are said to “know” how many slits are open, what electrons have done before them, and what electrons will do after them. Gribbin is not being careless. On the contrary, the passage is representative of a widespread and well-intentioned explanatory strategy in popular (and sometimes professional) accounts of quantum phenomena. Precisely for that reason, it is philosophically revealing.

The aim of the series is not to dispute the physics, nor to propose an alternative interpretation of quantum mechanics. Instead, it treats Gribbin’s explanation as a case study in explanatory strain: a moment where inherited metaphysical assumptions are no longer adequate to the phenomena being described, and where anthropomorphic and cognitive metaphors are pressed into service to conceal that inadequacy.

Across the posts that follow, we examine what these metaphors are doing, what conceptual work they are attempting to perform, and why they are so persistently tempting. We then show how the apparent mystery dissolves once we abandon the assumption that events must somehow build or coordinate patterns across time, and instead treat interference as the repeated instantiation of a structured potential defined by the experimental construal.

This analysis is continuous with the concerns of our recent work on relational ontology, but it is deliberately local and textually grounded. The two-slit experiment provides a compact site in which issues of potential, instantiation, temporality, and explanation converge. By staying close to a single, widely circulated explanation, the series aims to clarify not only what goes wrong in popular accounts of quantum phenomena, but why those accounts go wrong in the first place.