We have no good reason to believe that aliens have ever contacted Earth. Sure, there are conspiracy theories and some rather strange reports about harm to cattle, but nothing credible. Physicist Enrico Fermi found this odd. His formulation of the puzzle, proposed in the 1950s and now known as "the Fermi Paradox", is still key to the search for extraterrestrial life (SETI) and messaging by sending signals into space (METI).
Don’t forget the whole 13 billion years thing. The universe could be teeming with technologically capable life in the absolute sense yet have only a few intelligent/sapient species arise within the same hundred thousand year period, for example. Missed connections may abound.
Also, intelligence might not be the evolutionary advantage we think it is. It has a lot of drawbacks too (it’s very energy-intensive for one). Sharks are older than trees and never really changed since they evolved, with not that much intelligence to show for it.
Don’t forget the whole 13 billion years thing. The universe could be teeming with technologically capable life in the absolute sense yet have only a few intelligent/sapient species arise within the same hundred thousand year period, for example. Missed connections may abound.
Also, intelligence might not be the evolutionary advantage we think it is. It has a lot of drawbacks too (it’s very energy-intensive for one). Sharks are older than trees and never really changed since they evolved, with not that much intelligence to show for it.
Ever read Blindsight?
That breaks if they expand, though.