As I understand it, a civilization as it continues to advance and reaches a certain point it is no longer broadcasting into open space (as we have been doing since the 1930s), and instead reaches a point where all telecommunications are directed from space-bound craft back to Earth (think about our cable and satellite TV and radio overtaking conventional broadcast TV and radio). A Dyson sphere is the ultimate form of this concept. So, basically it is important for our planet to intentionally broadcast these types of scientific messages, as our unintentional broadcasts become less prevalent. An advanced civilization out there should be theoretically as quiet as we were in the '20s and '30s. There's a small window of opportunity to get some thing from them. And they could have the same philosophy as Wnt and Stephen Hawking warn us about- be quiet and don't contact other peoples. It is possible by making the first contact, being of a scientific encyclopedic message, we might be the beginning of trust. But of course it is possible history will say Earthlings are the ones everyone else in the galaxy should have been worried about...? (I suppose Earthling is correct, but someone please let me know)