Modest holography and bulk reconstruction in asymptotically flat spacetimes

In this work we present a ``modest'' holographic reconstruction of the bulk geometry in asymptotically flat spacetime using two-point correlators boundary quantum field theory (QFT) spacetime. The QFT lives on null spacetime, namely infinity and/or Killing horizons. relies two unrelated results: (i) there is bulk-to-boundary type correspondence between free fields living manifold and its boundary, (ii) one can construct metric by making use Hadamard expansion bulk. This that used are noninteracting not strong-weak duality sense AdS/CFT, but it works for generic subject to some reasonably mild conditions.