Holographic reconstruction of asymptotically flat spacetimes

Here, we present a "holographic" reconstruction of bulk spacetime geometry using correlation functions of a massless field living at the "future boundary" of the spacetime, namely future null infinity (sic)(+). It is holographic in the sense that there exists a one-to-one correspondence between correlation functions of a massless field in four-dimensional spacetime M and those of another massless field living in three-dimensional null boundary (sic)(+). The idea is to first reconstruct the bulk metric g(mu nu) by "inverting" the bulk correlation functions and re-express the latter in terms of boundary correlators via the correspondence. This effectively allows asymptotic observers close to (sic)(+) to reconstruct the deep interior of the spacetime using only correlation functions localized near (sic)(+).