Only if there is but one alien species out there and it's not curious. If there are several or many alien species, only one (besides us) has to be curious enough to explore the galaxy.
And if an intelligent life is not curious, it's questionable if it could be intelligent.
“And if an intelligent life is not curious, it’s questionable if it could be intelligent.”
It’s questionable to us, sure. Very hard to imagine even. But we are just going by the one example we have to guide us: us. We have a hard time imagining it because it’s not what we would do. But it’s yet to be proven what anyone else would do or not do.
Another possibility is the berserker scenario, where if we are detected moving things and being loud, something comes and squashes us. So new intelligences could be common, but after they reach a certain stage inevitably they are detected by something older and more powerful and eradicated.
Freegards