Unified Treatment of Null and Spatial Infinity III: Asymptotically Minkowski Space-times

Understand

The Spi framework provides a 4-dimensional approach to investigate the asymptotic properties of gravitational fields as one recedes from isolated systems in any space-like direction, without reference to a Cauchy surface.

• It is well suited to unify descriptions at null and spatial infinity because $\mathscr{I}$ arises as the null cone of $i^\circ$.
• The goal of this work is to complete this task by introducing a natural extension of the asymptotic conditions at null and spatial infinity, by 'gluing' the two descriptions appropriately.
• Space-times satisfying these conditions are asymptotically flat in both regimes and thus represent isolated gravitating systems.