The Zoom-in Zoom-out Hypothesis: Fundamentality and Completeness as Relative to Levels of Description

This preprint presents the Zoom-in Zoom-out Hypothesis, a speculative conceptual proposal on scale-relative fundamentality and completeness. It distinguishes a weak, epistemic reading (whether a system counts as fundamental depends on the level at which it is described) from a stronger, ontological reading (our observable universe may be a constituent of a higher-level domain, and apparently elementary entities may have lower-level structure). The paper compares the hypothesis with related work in scale relativity, effective field theory, emergence, brane-world cosmology, and the philosophy of fundamentality, states what it does and does not claim, and lists objections and replies. It is not an established or empirically confirmed theory and presents no testable prediction yet. It is shared for discussion and criticism.