[Paper Review] Are observers reducible to structures?

Ovidiu Cristinel Stoica|arXiv (Cornell University)|Jul 13, 2023

Philosophy and History of ScienceArts and Humanities3 citations

TL;DR

This paper argues that observers cannot be reduced to their structural properties alone, as different parametrizations of state space would otherwise lead to inconsistent perceptions of physical observables. It proves that only observers in a unique, privileged parametrization can reliably correlate memory with external facts, implying a non-reducible, observer-dependent correspondence between observables and physical properties—offering a foundational constraint for structural realism and the philosophy of mind.

ABSTRACT

Physical systems are characterized by their structure and dynamics. But the physical laws only express relations, and their symmetries allow any possible relational structure to be also possible in a different parametrization or basis of the state space. If observers were reducible to their structure, observer-like structures from different parametrizations would identify differently the observables with physical properties. They would perceive the same system as being in a different state. This leads to the question: is there a unique correspondence between observables and physical properties, or this correspondence is relative to the parametrization in which the observer-like structure making the observation exists? I show that, if observer-like structures from all parametrizations were observers, their memory of the external world would have no correspondence with the facts, it would be no better than random guess. Since our experience shows that this is not the case, there must be more to the observers than their structure. This implies that the correspondence between observables and physical properties is unique, and it becomes manifest through the observers. This result is independent of the measurement problem, applying to both quantum and classical physics. It has implications for structural realism, philosophy of mind, the foundations of quantum and classical physics, and quantum-first approaches.

Motivation & Objective

• To investigate whether observers can be fully reduced to their physical structure, independent of parametrization.
• To examine the implications of state space symmetries (unitary and canonical transformations) for observer reliability and perceptual consistency.
• To resolve the ambiguity in the correspondence between observables and physical properties by grounding it in the role of actual observers.
• To challenge structural realism and physicalism by showing that observer-like structures in different parametrizations cannot reliably track external facts.
• To establish that only one privileged parametrization supports genuine observers, while others are epistemically inert 'zombies'.

Proposed method

• Formalizing physical systems using quantum state space with Hilbert space structure and Hermitian operators as observables.
• Applying unitary and canonical transformations to show that the same physical structure can appear as different observables in different parametrizations.
• Defining observers as systems that correlate memory with external state via measurement-like processes.
• Proving via Theorem 1 that if all isomorphic structures were observers, memory would lack empirical correspondence with external reality.
• Using symmetry invariance to demonstrate that no unique mapping between observables and physical properties exists across parametrizations unless observers are privileged to one basis.
• Analyzing the consequences for foundational physics, including the Born rule and quantum-first approaches, by showing that only a fixed ontic basis supports consistent observation.

Experimental results

Research questions

• RQ1 Is there a unique, non-arbitrary correspondence between observables and physical properties, or is it relative to the parametrization of the state space?
• RQ2 If observers are reducible to their structure, can they consistently correlate their memories with the external world across different parametrizations?
• RQ3 What constraints does the reliability of observation place on the nature of observers in a fundamentally relational or symmetric physical theory?
• RQ4 How does the existence of multiple equivalent parametrizations affect structural realism and the ontological status of observers?
• RQ5 Can observer-like structures in non-privileged bases be considered genuine observers, or are they epistemically inert 'zombies'?

Key findings

• Observers cannot be reduced to their structure alone, as multiple parametrizations of the same structure would lead to inconsistent perception of physical properties.
• Theorem 1 proves that if all isomorphic structures were observers, their memories would have no reliable correspondence with external facts, making observation impossible.
• Only observers in a unique, privileged parametrization can maintain a stable, fact-corresponding memory of the external world.
• This implies a unique, non-arbitrary mapping between observables and physical properties, grounded in the existence of actual observers.
• Observer-like structures in other parametrizations are epistemically inert—functionally equivalent to philosophical zombies—because they cannot reliably track external reality.
• The result supports monistic views such as neutral monism or panpsychism, as it implies that physical properties are grounded in sentience, with a unique ontological basis for observation.