... or some others: 7: The universe is larger than our visible light cone. "They" may be "hiding" outside of our visible universe. 8: (even more mind-bending)

... or some others: 7: The universe is larger than our visible light cone. "They" may be "hiding" outside of our visible universe. 8: (even more mind-bending) "They" are hiding in the dark matter, i.e., they ARE dark matter :P A serious question to some scientist: assuming there exsits an alien civilization that is, say, a million years old, 500 000 ly away, and that they communicate in the spectrum we can detect. Wouldn't their EM radiation be overwhelmed ("erased") by star and other activity on its way to earth?