There's a perfectly consistent explanation that doesn't really break Occam's razor unless you have huge assumptions about AI takeoff and the drake equation: -

There's a perfectly consistent explanation that doesn't really break Occam's razor unless you have huge assumptions about AI takeoff and the drake equation: - These are really old things - They are autonomous and are driven by some computing system/AI - They have the ability to harvest, store, and leverage an immense amount of energy and convert it into propulsion (or more specifically, allows the repositioning of the object's atoms in spacetime) in a way we don't understand but doesn't break the laws of thermodynamics and allows travel at near light speed for long periods of time. - Their purpose isn't to communicate back to the origin (since the speed of light) but to autonomously take interventional action at their destination upon arrival based upon observation (this is the part that should scare you and if I were to go out on a limb is the reason these things aren't disclosed) That's it. Speculation about their original origin is irrelevant with regards to assuming it's an extremely unlikely thing for unmanned autonomous agents to exist with (a relatively incremental) post-human level of technological capability. If anything, there are many variants of resolving the drake equation which would make it surprising to not see such things, since it would imply there was never AI takeoff anywhere or any mechanism to deploy long-lived, self sufficient, autonomous probes. I'd expect us to be able to construct primitive versions of this within 100 years.