Quote (Malignanttumor666 @ 22 Mar 2023 06:00)
they died.
You night not be that far off. The life on this pale blue dot may be relatively young compared to the life that emerged elsewhere in this ginormous universe.
What may remain from alien civilizations which are now long gone are their techn, e.g, an autonomous probe or many such satelites that simply travel across the universe and whose sole goals are to gather data and to explore.