If no other life could exist anywhere in the universe would mean the universe is sterile. That we exists proves the universe is not sterile, but fertile. There would have to be overwhelming proof of the entire universe being sterile in order to completely negate the possibility of other life elsewhere.
There is no such proof.
If no other life could exist anywhere in the universe would mean the universe is sterile. That we exists proves the universe is not sterile, but fertile. There would have to be overwhelming proof of the entire universe being sterile in order to completely negate the possibility of other life elsewhere. There is no such proof. First, could exist and does exist aren't the same thing.
Second, if there are intelligent aliens, why aren't they here? That there are many civilizations but only one, us, with an urge to explore is as unlikely as many planets but only one, Earth, with native civilizations.