Jose Jaramillo

The theory of general relativity (GR) displays an array of universality features that are central to the operational use of the theory, such as detecting and extracting information from gravitational waves, while at the same time connecting to foundational issues, e.g., in the gravitational collapse setting or in the high-frequency limit of the theory (in the geometric optics approximation). Quite remarkably, these features can smooth out the details at a certain scale, namely through dissipative/smoothing mechanisms, in a way ensuring some level of predictive power (and simplicity) for the theory even when accurate control of the details is not at reach, either in principle or for operational reasons. We illustrate the role of such universality and dissipative/smoothing mechanisms in a series of examples, with a focus on binary black hole mergers, and we argue for the fruitfulness of (various forms of) asymptotic reasoning for identifying and investigating universal patterns in the GR context. In a broader perspective, we suggest that these latter may provide fundamental insights into the dynamics of (space)time in GR and beyond, in a way that is ‘agnostic’ to the underlying fundamental (e.g., quantum gravity) ontology.

How precisely to understand and evaluate counterfactuals can be an intricate issue. The aim of this article is to examine a new set of difficulties for evaluating counterfactuals that arise in the context of the dynamical spacetimes described by the theory of general relativity. The initial value formulation provides us with a methodology to pin down the specific combination of features of the theory at the origin of the difficulties, namely, non-linearity and certain non-local aspects, in particular when combined with the global and/or quasi-local character of physical quantities in general relativity. Finally, we connect the philosophical question about counterfactuals with concrete applied physical issues in general relativity about extracting meaningful predictions by constructing appropriate initial data sets, leading us to question the very suitability of the Cauchy approach to fully account for the explanatory power of the theory.

How precisely to understand and evaluate counterfactuals can be an intricate issue. The aim of this article is to examine a new set of difficulties for evaluating counterfactuals that arise in the context of the dynamical spacetimes described by the theory of general relativity (GR). The initial value formulation provides us with a methodology to pin down the specific combination of features of the theory at the origin of the difficulties, namely, non-linearity and certain non-local aspects (typically captured by ellipticity at the analytical level), in particular when combined with the global and/or quasi-local character of physical quantities in GR. Finally, we connect the philosophical question about counterfactuals with concrete applied physical issues in GR about extracting meaningful predictions by constructing appropriate initial data sets, leading us to question the very suitability of the Cauchy approach to fully account for the explanatory power of the theory.