NASA Scientist Proposes Theory of Alien Civilizations Throughout Milky Way
The Milky Way may host modest numbers of civilizations only slightly more advanced than humanity that face similar limitations and eventually abandon interstellar exploration.
Bored aliens': has intelligent life stopped bothering trying to contact Earth?
The Milky Way may host a few civilizations only marginally more advanced than humanity, producing weak or absent technosignatures and thus remaining hard to detect.
