Why We Might Be Alone

We may haven't met aliens because they were all destroyed by self-replicating robotic probes. These invisible machines could be roaming the galaxy to ensure no other civilization ever poses a threat.

This unsettling theory suggests that advanced civilizations send out automated drones to wipe out any potential rivals before they become dangerous. If a machine can copy itself indefinitely, it could scour the entire galaxy for life in just a few million years. This implies that the cosmos might be a graveyard of quiet civilizations that were purged by machines. It is a chilling answer to why the vast, starry sky remains so strangely silent.