We make contact with an alien species but a simple test, repeated ad nauseum, reveals they are actually made of antimatter. We learn to communicate and it turns out they are from a vast network of other species stretching accross the universe, all of which are made of antimatter. We are distraught because it means we can never "contact" them or, it would seem, anything in the universe outside our solar system. But they are delighted to study us and to basically treat us like royalty. The problem, of course, is they can't actually give us anything because it would be made of antimatter. So the trick of how to guide and even govern a whole world where the only availible interaction is communication signals or mass extinction events come into play. We grow sharply uninterested in space exploration as we know there is nothing to explore and we further assume that they just see us as an enormous fuel source, having dealt with such people on our own planet. We think they are just trying to get us to willingly fly our bodies and ships to combustion chambers. Combined with being showered by positive encouragement from them we quickly become a "bratty" world - even more so than we already are, in fact.
