There's also the Three-body problem (https://en.wikipedia.org/wiki/Three-body_problem https://en.wikipedia.org/wiki/Three-body_problem) answer: anyone who knows

There's also the Three-body problem (https://en.wikipedia.org/wiki/Three-body_problem https://en.wikipedia.org/wiki/Three-body_problem) answer: anyone who knows what's good for them is hiding. Any interstellar-civilization which reveals its presence is destroyed in a first strike by another civilization in hiding. Any self-replicating probes are also hiding (because there's no meaningful distinction between a self-replicating probe and an interstellar civilization anyway).