I think an argument could be made that they have left subtle visible effects, and we just haven’t been able to reach consensus that that’s what it is, and one of these days we’re going to correlate the universe’s contents, and when we do, we’re going to be a bit upset.
We don’t seem to be sure what the deal was with oumuamua, and we’re constantly getting reports of what look like alien probes on earth, but we (at least, whatever epistemic network I’m in) can only shrug and say “These things usually aren’t aliens.”
I think an argument could be made that they have left subtle visible effects, and we just haven’t been able to reach consensus that that’s what it is, and one of these days we’re going to correlate the universe’s contents, and when we do, we’re going to be a bit upset.
We don’t seem to be sure what the deal was with oumuamua, and we’re constantly getting reports of what look like alien probes on earth, but we (at least, whatever epistemic network I’m in) can only shrug and say “These things usually aren’t aliens.”