![]() For most of Vistarini's discussion, the relevant notion of emergence is ontological (not epistemic) and is an instance of metaphysical explanation, or grounding (not supervenience). The first delineates the senses of emergence at issue. The book opens with two chapters of philosophical and physical stage-setting. But this is part of Vistarini's point: string theory exhibits a "quite composite notion of spacetime emergence", and attention to the details of the theory is required for "producing a metaphysics sensitive to the physics occurring at the Planck scale" (ix). So you will find no simple take-home message about background independence or emergence in general. These lessons are not deeply systematized: they do not result in an explicit account of background independence or emergence, nor are they used to critique extant accounts of these notions. Vistarini takes a physics-first approach, beginning each case study with a description of the relevant physics and then drawing lessons about background independence and emergence from this description. The execution of this argument is likely to be most interesting to philosophers of physics that have at least a nodding acquaintance with string theory. ![]() According to string theory, Vistarini argues, space and time are not "built into the fundamental structure of the physical world", but are "derived, emergent structures" (12). Taken together, these cases are meant to show something stronger: string theory doesn't just take the structure of spacetime to be contingent, it repudiates a spacetime background entirely. Her defense consists of five vignettes, each presenting some feature of string theory as evidence that the theory makes no illicit assumptions about spacetime's necessary features. In her book, Tiziana Vistarini defends string theory from the charge of background dependence, arguing that the theory "shows background independence in different ways and degrees" (ix). In particular, this complaint is usually levelled at string theory. This principle is often invoked to reject quantum theories of gravity on which facts about spacetime are insufficiently contingent. In both communities it is often said that one of the great lessons of Einstein's theory is the principle of "background independence", which advises against attributing any fixed, necessary features to spacetime. For physicists, spacetime is inseparable from gravity, especially in the light of Einstein's general theory of relativity. For philosophers, spacetime is intertwined with issues of persistence, determinism, and more. Physicists and philosophers are both invested in the nature of space, time, and spacetime, and they often look over each other's shoulders for insight and guidance.
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