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 ℐ⁺. 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 ℐ⁺. The idea is to first reconstruct the bulk metric gμν 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 ℐ⁺ to reconstruct the deep interior of the spacetime using only correlation functions localized near ℐ⁺.