Exactly, MigBuster. We have no proof, one way or another. But things are more interesting when you consider they might exist.

This blue marble is a lot blander, boring and scary if we latch on to the grim notion we're alone. And some dictatorial nutbag in some nation somewhere is hovering his finger over a red button that could unleash global thermonuclear war, destroying this precious treasure...

Nothing but dust and rocks and blazing embers, swirling around the cosmic black-hole drain.