 The issues raised by such radical proposals are complex, and it is even debated whether they are empirically coherent, given the role that space and time play in our understanding of physical causation and empirical observation, and hence of empirical evidence itself. For present purposes, the key point is that such theories propose systematic theoretical reductions, akin to the reduction of thermodynamics to statistical mechanics, with a concommitant ontological reduction of the structures of the reduced theories. In this, the case appears unlike the relationship between physics and biology as weak emergentists see it, in which biological entities appear to be special kinds of organized physical structures that explain equally distinctive phenomena that are unexplained by more fundamental theories. For a non-technical introduction to some of the theories at issue and the case for describing them as entailing spacetime emergence, see Wüthrich (2019). For more general philosophical reflection on our ordinary concepts of space and time and their compatibility with theories that treat them as nonfundamental, see Chalmers (forthcoming).