How to be an orthodox quantum mechanic

TL;DR

This paper empirically infers the orthodox quantum mechanics viewpoint by surveying 42 popular textbooks and scoring their stance on 13 propositions across three thematic pillars: the nature of the quantum state, the behavior of particles, and the origin of probabilistic predictions. Using a triage scoring scheme and temporal subsamples, it finds a Copenhagen-like core—centering on measurement disturbance, single-instance description by the state, and no pre-measurement values—while also uncovering significant post-1980 fragmentation and evolving consensus on several points. The study demonstrates strong correlations among core propositions and shows that while the orthodox view remains robust, recent texts increasingly diverge, potentially signaling a shift in how the orthodoxy is understood or taught. Overall, textbook-based orthodoxity closely aligns with traditional Copenhagen intuitions but exhibits growing heterogeneity that mirrors broader debates in quantum foundations and interpretations.

Abstract

This work sets out to answer a single question: what is the orthodox interpretation of quantum mechanics? However, we adopt a different approach to that normally used. Rather than surveying physicists, or poring over the precise details of the thoughts of Bohr and Heisenberg, we review a collection of 42 textbooks on quantum mechanics, encompassing the most popular and prominent works of this nature. We then gauge their response to 13 propositions to build up a picture of exactly what is believed by an orthodox quantum mechanic. We demonstrate that this orthodoxy has many aspects of Copenhagen-like viewpoints, but also shows some interesting emerging deviations. Moreover, it is more nuanced than some reductive characterisations that condense the orthodoxy down to the ontological primacy of the quantum state. The revealed orthodoxy has three consistent pillars: measurement inherently disturbs quantum states, these states refer to individual instances, not ensembles, and quantum systems do not have definite properties prior to measurement. More fully, it entails that individual particles exist in wave-like super-positions and present particle behaviours only when forced to by outside influences. The act of measuring such a system inherently induces random changes in its state, manifesting as a form of measurement error that corresponds to the uncertainty principle. This implies that measurement does not reveal underlying values of quantum properties.

Figures (6)

• Figure 1: Affirmation frequency for responses to each question as a function of time. The bars represent different samples: pre-1980 (grey), post-1980 (green), and post-2000 (magenta). The error bars reflect the effect of including values inferred for logical consistency.
• Figure 2: Affirmation frequency for responses to each question for various subsamples. The bars represent different samples: all (black), undergraduate (yellow), graduate (blue), Wikipedia notable (red). The error bars reflect the effect of including values inferred for logical consistency.
• Figure 3: Rejection frequency for responses to each question as a function of time. The bars represent different samples: pre-1980 (grey), post-1980 (green), and post-2000 (magenta). The error bars reflect the effect of including values inferred for logical consistency.
• Figure 4: Rejection frequency for responses to each question for various subsamples. The bars represent different samples: all (black), undergraduate (yellow), graduate (blue), and Wikipedia notable (red). The error bars reflect the effect of including values inferred for logical consistency.
• Figure 5: The "orthodoxity" or degree to which each studied source agrees with the averaged responses to each proposition. This is ordered by date of first publication.