The trouble with the aliens is that it’s too good an explanation. Inscrutable beings with tech we don’t don’t understand works as an explanation of just about anything, so if we allow that in our explanatory toolbox we’ll end up crying “aliens” for all sorts of hard-to-explain phenomena. In most of those cases we’d have found a mundane explanation if we looked longer and thought harder. Non-falsifiable, broad spectrum theories like aliens and magic need to go last on the list, down below “we don’t know yet, let’s gather more data,” or we’ll end up fooling ourselves.
If there really are aliens, eventually we should have enough evidence that we can build specific, falsifiable theories about particular, well-defined entities with at least rough bounds on capabilities. But we’re not close to that point yet.
If there really are aliens, eventually we should have enough evidence that we can build specific, falsifiable theories about particular, well-defined entities with at least rough bounds on capabilities. But we’re not close to that point yet.