So, where? (Article stops at this) Maybe they are drifting in space most of the times, and land on asteroids to quickly mine them? Why should be there even a s

So, where? (Article stops at this) Maybe they are drifting in space most of the times, and land on asteroids to quickly mine them? Why should be there even a slightest sign of them?This “we should see them” is based on assumptions from popscifi, but are they realistic? What if physics is mostly solved this time (or at least will not bring anything startrek-y anymore), and there is no way for an alien to broadcast to the universe or cross even tiniest its part in a meaningful time?