Is everything quantum?

Determine whether all physical systems and phenomena are fundamentally quantum mechanical in nature, establishing whether quantum mechanics provides a universal description with no exceptions.

Background

The paper frames foundational uncertainties about the scope of quantum mechanics by citing Paul Davies’s categorization of open questions at the quantum frontier. Within the author’s broader discussion of the quantum-to-classical transition and the universal wave function, this question probes whether the apparent classical world is entirely emergent from quantum substrates or whether any non-quantum domains exist.

This question is presented among a set of explicitly labeled open questions to situate the paper's hypothesis—maintaining a universally quantum reality while explaining classical perception through decoherence and statistical realizations—against the wider unresolved landscape.