French physicists James Hefford and Matt Wilson have proposed a mathematical model called QBox, outlining a post-quantum layer of reality that could bridge quantum theory and gravity. The theory introduces 'hyperdecoherence,' allowing quantum mechanics to emerge from a deeper realm with indefinite causality. Experts praise the work as a promising step toward quantum gravity.
James Hefford at France's National Institute for Research in Digital Science and Technology and Matt Wilson at Paris-Saclay University have sketched QBox, a post-quantum theory addressing gaps in quantum mechanics when dealing with gravity-dominated large-scale phenomena. Hefford stated, “Quantum theory doesn’t describe the entire universe. One of the greatest problems in physics is to come up with a theory of quantum gravity, a theory that describes both quantum theory and gravity. That thing ought to somehow go beyond just quantum theory.” The model draws from decoherence, which explains why quantum effects vanish in everyday classical reality, proposing an analogous 'hyperdecoherence' process for quantum emergence from QBox dynamics. The research overcomes a 2018 theorem deeming hyperdecoherence impossible by relaxing certain assumptions, resulting in a realm where causality is indefinite—events can mix forward and backward influences without clear order. Carlo Maria Scandolo at the University of Calgary called this 'causal indefiniteness' relevant for quantum gravity pursuits, noting general relativity's varying cause-effect orders in spacetime. Hyperdecoherence hides temporal dimensions, blocking access to past-directed processes for quantum observers, according to Wilson. Ciarán Gilligan-Lee at Spotify's Causal Inference Research Lab commended the theory's minimalism and success in reproducing quantum mechanics. John Selby at the University of Gdańsk urged fleshing out physical details for experimental relevance. The work appears in Physical Review A, with potential tests in quantum wave overlap experiments and hints at deeper theory towers.