Causal Constrains on Simultaneity and the Structure of Physical Entities

Classical physics treats interactions between physical entities as continuous and physically simultaneous, an assumption that underlies superposition principles and standard multi-body dynamics. In this work, we analyze the causal implications of this assumption and argue that it leads to structural tensions in the consistent ordering of physical influences. In particular, the assumption of physical simultaneity appears to prevent a coherent causal ordering and may be associated with the well-known loss of predictability in three-body and many-body systems. Relaxing physical simultaneity suggests that interactions may require causal ordering at a microscopic scale, implying an intermittent rather than continuously overlapping structure of interaction. This perspective challenges the notion that observable physical entities can be fundamentally simple, as the coexistence of multiple interaction properties and structured trajectories appears difficult to reconcile with genuine simplicity. These considerations point toward the possible necessity of a deeper fundamental scale composed of genuinely simple elements, from which microscopic structure, trajectories, and observable behavior may emerge. The present work formulates the causal constraints motivating such a perspective without committing to a specific microscopic model.