Exactly. Which DISPROVES the idea of aliens from another galaxy visiting us. From this galaxy? Nah, we can't find any viable life.
The distances alone, under Einstein's theory, prove it would take longer than the entire history of our galaxy to get here.
And even if you believe in warp drive like in Star Trek, the distances are still so vast as to be impossible to travel within our entire history.
And how would they even know we were here? Our techology is so new that radio and other transmissions that have been travelling in space, at the speeds they do, would take billions upon billions and trillions of years to even reach another galaxy even if they have advanced receiving technology. So then it would take more billions of years to get here and our entire solar system will be gone by then.
Now, if you want to then add in the possibility of wormholes, black holes, dark space, etc., you still have vast amounts of distance.
I'd believe in alternative universes before I believe in visitors from our own.
and how about time travel?? =o)