I would say it’s probably close to zero, depending on what physics actually allows. If FTL travel turns out to be completely impossible, then it’s exactly zero. If some sort of FTL travel is possible, it’s slightly above zero. If you can travel faster than 10^9 c, that’s when distances stop being a huge problem. Before that though, distance ruins my dreams.
They don’t have to visit us to exist!
The likely hood of said aliens visiting us is also zero.
Care to elaborate? Why is it zero?
Distance.
Space is incomprehensibly big.
I would say it’s probably close to zero, depending on what physics actually allows. If FTL travel turns out to be completely impossible, then it’s exactly zero. If some sort of FTL travel is possible, it’s slightly above zero. If you can travel faster than 10^9 c, that’s when distances stop being a huge problem. Before that though, distance ruins my dreams.