If I recall in the 3 body series the use of the FTL drives were like a beacon to anyone paying attention, and everyone powerful enough paid attention just so they could destroy other civilizations as quickly and inexpensively as possible. Pretty grim stuff, one plausible theoretical explanation why we seem to be alone so far.
Freegards
Recently my reading had me wondering about the “UFO” phenomenon. I find it curious that “believers” claim our detonation of nuclear weapons attracted them. If you look at the history of the whole thing there was almost no interest in UFOs during the war. Sure there were observations of “foo fighters” but these were not even heard of until long after the fact. The real peak in UFO sightings comes AFTER the war.
Sure, a spacefaring civilization might want to put up sensors to detect when another civilization “became nuclear” but such a civilization would certainly know to detect that civilization BEFORE it did. If they could erect gamma detectors that could detect a detonation they could as well detect scattered gamma sources being collected into “near critical mass” lumps and would be smart enough to realize the value of the more sensitive detectors.
So IF we were “being visited” because of becoming a “nuclear civilization” those visits would likely have been much more prolific just before the fact. Now I grew up in the 50s and recall even then youngsters were encouraged to frequently scan the skies and identify every flying object. I still remember the cards everyone had to aid in “airplane identification” with silhouettes of all the planes. Imagine, during the war such efforts were really made. Folks educated highly in what to expect when they look up and reason to be scanning the skies at every opportunity. Yet during the war outside of a few “foo fighters” no UFOs were seen.
Yet years later when much less effort was being expended to encourage identifying objects in the sky there were thousands of sightings and Project Bluebook had to be started to look into it. Logically, I think one can rule out UFOs as actually existing. If there were UFOs and IF their interest in us were stimulated by our technology then there should have been a flurry of visits observed DURING the war when we had literally, armies in the air looking for them.
The UFO phenomenon comes not during a time of great unification of national purpose when it should have but afterwards during a time of upheaval and stress. That tells me the phenomenon says more about US than them.