The Quantum Measurement Problem: A Review of Recent Trends

TL;DR

This review paper discusses the longstanding quantum measurement problem, exploring various interpretations and approaches like decoherence, many-worlds, and collapse theories, highlighting current understanding and unresolved issues.

Contribution

It provides a comprehensive overview of recent developments and perspectives on the quantum measurement problem, clarifying distinctions among interpretations and summarizing key theoretical approaches.

Findings

Decoherence explains apparent wavefunction collapse without actual collapse.

Many-worlds interpretation offers a deterministic account of measurement.

Objective collapse theories propose modifications to quantum mechanics to resolve the problem.

Abstract

Left on its own, a quantum state evolves deterministically under the Schr\"odinger Equation, forming superpositions. Upon measurement, however, a stochastic process governed by the Born rule collapses it to a single outcome. This dual evolution of quantum states -- the core of the Measurement Problem -- has puzzled physicists and philosophers for nearly a century. Yet, amid the cacophony of competing interpretations, the problem today is not as impenetrable as it once seemed. This paper reviews the current status of the Measurement Problem, distinguishing between what is well understood and what remains unresolved. We examine key theoretical approaches, including decoherence, many-worlds interpretation, objective collapse theories, hidden-variable theories, dualistic approaches, deterministic models, and epistemic interpretations. To make these discussions accessible to a broader audience, we also reference curated online resources that provide high-quality introductions to central concepts.