Identify a post-Relativistic space-time structure compatible with quantum nonlocality
Determine a concrete space-time structure and accompanying notion of causal dynamics that can replace the space-times of Special Relativity and General Relativity while remaining empirically adequate and accommodating the experimentally verified nonlocal correlations predicted by quantum theory (e.g., Bell-inequality and GHZ violations), thereby enabling a coherent unification that abandons Relativistic locality yet preserves observed relativistic phenomenology where appropriate.
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What sort of space-time structure should be used in place of the space-time of Special Relativity or the space-times of General Relativity is not at all clear, and should be a question given the highest level of attention by anyone seeking to "reconcile" quantum theory with Relativity.