Theories Avoiding ‘superdeterminism’ Now Have Clear Testing Standards

Researchers at the Institute for Quantum Studies, led by Mordecai Waegell, have formalised the criteria a physical theory must meet to be considered nonsuperdeterministic. The research focuses on how theories determine measurement outcomes through ontic states and response functions. It offers a standard for assessing statistical independence in experimental procedures. This clarifies the meaning of freedom and independence in measurement settings. It further links superdeterminism and contextuality, and highlights how differing theoretical frameworks can produce identical empirical data. This offers key insights into the interpretation of quantum mechanics.

Formalising criteria to differentiate genuine randomness from apparent statistical independence

Requirements for physical theories to avoid superdeterminism are now formalised. The standard establishes that both individual samples and measurement outcomes must be representative of observed distributions. Previously, assessing this representativeness was subjective and lacked a clear threshold. This relied heavily on philosophical interpretation. Detailed in research published on April 2, 2026, the new standard provides a benchmark for evaluating statistical independence in experiments. It moves beyond philosophical arguments about free will to focus on quantifiable criteria. This is particularly relevant given the ongoing debates surrounding Bell’s theorem and the interpretation of quantum entanglement, where the appearance of non-locality challenges classical notions of causality.

The research clarifies how a theory defines randomness and freedom by examining ‘ontic states’, the complete underlying properties of a physical system, and ‘response functions’, detailing how measuring devices react to it. This criterion builds upon earlier work defining superdeterminism as systematic violations of statistical independence. To create experimental ensembles, effective preparation procedures must yield representative samples reflecting the broader population. Both individual samples and measurement outcomes must mirror observed distributions. Crucially, the representativeness isn’t simply about achieving statistical averages. It demands that the sampling process itself doesn’t introduce correlations that would falsely suggest randomness where none exists. This necessitates a rigorous mathematical framework for evaluating the fidelity of sample selection.

Physical theories must account for properties defining the prepared ensemble, such as the characteristics of elements within it, when determining expected outcomes. A theory’s ontic states and response functions determine how well samples represent the ensemble. This potentially leads to systematic violations of statistical independence. This interplay between ontic states, response functions, and sample representation is crucial for establishing genuine randomness. Consider, for example, a scenario involving polarised photons. The ontic state would encompass the photon’s polarisation direction, while the response function would describe how a polarisation filter reacts to photons of different orientations. If the preparation procedure systematically favours certain polarisation angles, it would violate the criteria for nonsuperdeterminism, even if the observed statistics appear random. The formalisation allows for a precise calculation of the degree to which such biases might exist.

Formalising nonsuperdeterminism provides a testable criterion for quantum theories

A clear standard for what constitutes a nonsuperdeterministic theory represents a key step towards understanding the foundations of quantum mechanics and resolving debates about locality and realism. The authors concede, however, a significant limitation. Demonstrating that any existing physical theory actually meets this newly formalised standard remains an open question. This isn’t merely a technical hurdle, but a fundamental challenge. Different theories can generate identical experimental results despite differing underlying assumptions about how reality operates. This is known as empirical underdetermination. It highlights the difficulty of definitively proving or disproving a theory based solely on experimental data. The formalisation provides a necessary, but not sufficient, condition for a viable physical theory.

Establishing a key benchmark for evaluating existing and future physical models, this work does not diminish in value despite the lack of demonstrably satisfying current theories. The research establishes a formal criterion for assessing whether a physical theory allows for genuine randomness. It focuses on quantifiable characteristics. By defining ‘nonsuperdeterministic’ theories as those where both individual instances and measurement results accurately reflect broader observed patterns, a benchmark for evaluating statistical independence has been created. This is significant because many interpretations of quantum mechanics, including those relying on hidden variables, implicitly assume a degree of superdeterminism to explain away the apparent non-locality. The formalisation provides a means to rigorously test these assumptions. Centred on how a theory links underlying properties to measurement outcomes via response functions, detailing how a measuring device reacts, this rigorous standard clarifies the requirements for theories attempting to explain quantum entanglement without invoking hidden variables or restrictions on experimental freedom. Ontic states represent a system’s properties, and response functions dictate measurement outcomes. This allows for further investigation into the implications of this approach. The connection between superdeterminism and contextuality, the dependence of measurement outcomes on the complete experimental context, is also illuminated. This suggests that any theory exhibiting strong contextuality may also be susceptible to superdeterministic interpretations.

Furthermore, the framework allows for a more nuanced understanding of the role of statistical independence in experimental design. Researchers can now explicitly quantify the degree to which their experiments rely on assumptions of independence, and identify potential sources of systematic error. This is particularly important in the context of quantum technologies. Maintaining the coherence of quantum states requires precise control over experimental parameters. The ability to formally assess the validity of statistical assumptions is therefore crucial for ensuring the reliability and accuracy of quantum devices. The work presented by Waegell and colleagues provides a valuable tool for navigating the complex landscape of quantum foundations and developing a more complete and consistent understanding of the physical world.

The research successfully formalised the requirements for a physical theory to be considered nonsuperdeterministic, establishing a standard for statistical independence. This matters because many interpretations of quantum mechanics rely on superdeterminism to account for entanglement, and this work provides a way to rigorously test those assumptions. By focusing on ontic states and response functions, the researchers created a benchmark to evaluate whether experimental outcomes genuinely reflect observed distributions. The authors suggest this framework will be valuable for assessing statistical assumptions, particularly in the development of quantum technologies.