To answer the Fermi Paradox, some theorized that there may be aliens out there who purposefully did not Contact us.  They thought that one large power or a council of powers could have made the decision that Earth, and perhaps other worlds, were not to be Contacted.  Recently other races have told us that the Peloran banned visitation with Earth.  Aggressively.  Whether true or not, we know they made Contact after we found a way through The Wall.  Was that a test?