This is the key point. Most people fail to understand the truly impossible scale of the challenge to travel between the stars. Why would the visitors then make

This is the key point. Most people fail to understand the truly impossible scale of the challenge to travel between the stars. Why would the visitors then make themselves impossible to see or find? The usual response to this is they’ll have some sort of magical way of interstellar travel we don’t understand that makes it not so hard. Meh. Doesn’t ring true. I’ll believe aliens are here when a starship hauls in and parks. And I’ll be very, very concerned at that point about exactly what it is they want.