I have a new paper out, titled “Relational Quantum Mechanics, Causal Composition, and Molecular Structure”, published in the journal Foundations of Chemistry (see links at the end of this post). The topic concerns the relationship between chemistry and quantum mechanics (QM), and is sometimes called the problem of molecular structure. (The paper expands on some ideas I discussed awhile back in a blog post.) Here is the abstract:
The problem is this: while chemists successfully describe molecules using QM models, it turns out that one of the most important determinants of chemical properties is generally not derived from QM. This is molecular structure—the equilibrium spatial relationships between atomic centers. Instead, this crucial information is drawn from experimental evidence and put into the models “by hand.” What accounts for this situation, and how should it impact our view of the relationship between chemistry and physics?
The topic is simultaneously niche and widely relevant. It is niche in the sense that only a relatively small number of philosophers and theoretical chemists work on it, but it impacts broader discussions about the relationship between phenomena at different scales. Are entities and properties described by the various “special sciences” all ultimately describable in-principle by physics? Many philosophers work on various versions of this topic while assuming that, at least, chemistry is reducible, in some sense, to physics. But the problem of molecular structure seems to call this assumption into question.
Ultimately, I think quantum mechanics can, in principle, describe molecules with their distinctive (often highly asymmetric) spatial configurations. But reaching this conclusion requires going beyond the formalism of the models and engaging in a good deal of philosophical interpretation of QM (note that, given their complexity, even isolated molecules cannot be mathematically described without simplifying assumptions, and accounting for molecular structure also requires consideration of the numerous internal and external interactions responsible for shaping molecules). My favored approach uses the stance called relational quantum mechanics combined with an ontology that features my own version of causal process theory. Bolstered by these additional conceptual resources, we can envision how QM can account for molecular structure.
Here is a link to the published paper.
Here is a special link for online viewing (for those without subscription access)
Here is a the penultimate version of the paper (post peer review, but before final editing for publication).
This is a part of a larger project of mine that proposes a unified causal-ontological framework capable of supporting explanations across the natural sciences. After a few years of not attempting to publish anything post dissertation, I’m now seeing if I can get some more of it out there.