• Wednesday 24 May 2017 at Geneva – Samuel Fletcher (Minnesota): Reduction, emergence, and direct limits

Abstract: Most discussions of spacetime emergence and the “physical salience” of the structures employed in theories of quantum gravity have understood these terms informally. Applying some new formal definitions based on “similarity structure” on models of theories, I show how to make more precise the sense in which a physical continuum of events could be emergent, and to connect the discussion of physical salience with a precise definition of intertheoretic reduction. As a test example, I consider claims about the emergence of the continuum of relativistic spacetime from direct limits of causal set histories, showing how their justification, though presently incomplete, could be completed. Time permitting, I will comment on the relation between this approach and causal set theory’s hauptvermutung. In terms of technical difficulty, this talk rates 4/5

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