My theory is that these are old autonomous probes that are part of a system designed to prevent any civilization from developing technology which would threaten

My theory is that these are old autonomous probes that are part of a system designed to prevent any civilization from developing technology which would threaten the origin. It’s a relatively inductive thing to assume that if humans get past any great filters we will look upwards for external existential threats by those other civilizations which do not get through, and whose failure may be due to development of tech which could harm us. A fair countermeasure would be to deploy autonomous probes that slowly blanket the galaxy and monitor and destroy threats. It would genuinely surprise me if we are here in 100 years that we wouldn’t have created and deployed such technology as a way to protect our ancestors future from external threats. This only makes sense once all major x-risk is paid down due to manmade technology and natural threats, but once so it seems inevitable this is the next thing our civilization will seek to protect against. My suspicion is that these are real, are inaccessible to us, and always will be, at least until we get close to any kind of galaxy-level x-risk technology like AGI. At which point, we will either be wiped out or will be warned. It’s actually quite a boring explanation since it doesn’t require too many leaps of logic, doesn’t break any laws of physics, and leaves us potentially alone in the present day universe (the origin of these may be long gone.)