Through the Forest of Quantum Measurement

A guided tour of a famously messy debate—decoherence, collapse, many worlds, hidden variables, and even quantum field theory.

Full disclosure: none of us are “quantum foundations people” by training. That’s not a marketing pose. It’s the origin story of this review.

Anderson A. Tomaz, Rafael S. Mattos, and I had started digging into gravitationally induced wavefunction collapse in molecules. To do that responsibly, we needed to understand what “collapse” is even supposed to mean—mechanistically and conceptually—before we could ask whether gravity might have anything to do with it.

That reading phase quickly turned into a different kind of project. The measurement problem sits at the intersection of physics, philosophy, and (occasionally) mathematical logic, and it has accumulated a truly gigantic literature. But what struck us wasn’t just the volume. It was the sociology of it: many subfields felt oddly disconnected, reviews often stayed either historical or narrowly thematic, and a lot of work seemed to happen in small, self-contained circles. So we did what we would do when a new research area looks like a rainforest with no map: we tried to draw the map.

For about a year we surveyed hundreds of papers, keeping our minds open—because in this territory, it’s dangerously easy to “solve” the problem by declaring your preferred interpretation a priori. The review that came out of that effort is now available as “The Quantum Measurement Problem: A Review of Recent Trends,” published at the Philosophical Magazine C.

The structure is simple, but the goal is ambitious. We introduce the measurement problem carefully, then treat decoherence as the modern baseline: it explains how interference becomes practically unobservable and why certain “pointer” bases get selected through environment-induced monitoring. Yet decoherence does not by itself explain why we experience a single outcome—what Schlosshauer calls the “problem of outcomes,” and what many philosophers would describe as the remaining bite of the problem.

From there we survey the main competing families—Many-Worlds, objective collapse models, hidden-variable approaches, epistemic interpretations, deterministic models, and also views that deny the measurement problem is a real problem at all.

We also make a point of discussing measurement in quantum field theory, because QFT is where modern physics actually lives, and foundations work that treats it as an afterthought is leaving a trapdoor under its own feet.

Before finalizing the manuscript, we contacted specialists across subfields and asked them to comment. We’re grateful that many did—among them Stephen Adler, Jacob Barandes, Lajos Diósi, Christopher Fewster, Nicolas Gisin, and Carlo Rovelli (and many others acknowledged in the paper). Their feedback didn’t make the controversies disappear, of course. But it did help us state positions more fairly, and sharpen the boundaries between what is solidly understood and what is still genuinely up for grabs.

Finally—and this is the part that may look unorthodox—we deliberately include curated non–peer-reviewed resources (essays, books, videos) as a kind of “secondary map.” The point isn’t to replace technical literature. It’s to give readers a set of ramps into notoriously opaque material, in plain language, so they can arrive at the primary sources with fewer bruises. The paper argues that these resources, used carefully, are legitimate entry points—especially for newcomers trying to build a coherent mental picture before drowning in formalism.

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Reference

[1] A. A. Tomaz, R. S. Mattos, M. Barbatti, The quantum measurement problem: a review of recent trends, Philos. Mag. (2025). 10.1080/14786435.2025.2601922