Collapse. What else?

TL;DR

This paper addresses the quantum measurement problem, arguing it is a fundamental physics issue that requires a physical solution, possibly involving modifications to quantum dynamics such as stochastic equations.

Contribution

It critically analyzes existing interpretations like many-worlds and Bohmian mechanics, proposing that a modified dynamics approach is the most promising resolution.

Findings

Many-worlds and Bohmian mechanics effectively involve collapses during interactions.

The measurement problem is a fundamental physics issue, not just interpretation.

Modified dynamics, such as stochastic Schrödinger equations, may resolve the problem.

Abstract

We present the quantum measurement problem as a serious physics problem. Serious because without a resolution, quantum theory is not complete, as it does not tell how one should - in principle - perform measurements. It is physical in the sense that the solution will bring new physics, i.e. new testable predictions, hence it is not merely a matter of interpretation of a frozen formalism. I argue that the two popular ways around the measurement problem, many-worlds and Bohmian-like mechanics, do, de facto, introduce effective collapses when "I" interact with the quantum system. Hence, surprisingly, in many-worlds and Bohmian mechanics, the "I" plays a more active role than in alternative models, like e.g. collapse models. Finally, I argue that either there are several kinds of stuffs out there, i.e. physical dualism, some stuff that respects the superposition principle and some that doesn't, or there are special configurations of atoms and photons for which the superposition principle breaks down. Or, and this I argue is the most promising, the dynamics has to be modified, i.e. in the form of a stochastic Schr\"odinger equation.