Envision civilizations tombstone: A automated observatory, which searches for green-zone planets and sends short laser-burst-encoded "Here lies"- messages to the probable locations of tomorrow civilizations.

On some far away planet, a circle of far-travelled pulsing light razes with 30 km/s over the clouds, and is interpreted as a answer to the "Where is everybody?" question, missing the grammatically correct point of a decent interstellar conversation. The Question is.. "Where was everybody (when we where around?)"