What makes you an observer?

Both empirical and theoretical objective science can only access relations, revealing nothing about the intrinsic nature of the entities "in relation". We typically refer to these entities as "matter", assuming their nature is irrelevant and that relational structures alone explain all phenomena, including consciousness. This would imply that consciousness arises not from matter itself but solely from its structural configurations. Consequently, if two worlds possess isomorphic structures and obey identical dynamical laws, isomorphic systems within these worlds should be equally sentient or insentient. I demonstrate that if this premise held true, the memories within an observer's brain would bear no correlation to the external world. Yet since we do acquire knowledge of the external world, structure alone must be insufficient: there exists something beyond relations, the intrinsic essence of the "stuff in relation". This essence imbues the observer's structure with sentience, metaphorically "breathing fire" into it. In turn, the observer confers physical meaning upon the world's structures. Remarkably, this conclusion emerges directly from physics and mathematics. Without acknowledging this intrinsic element, we would be incapable not only of subjective experience but also of acquiring any objective knowledge about the physical world.