Or... is it possible that we are not supposed to meet the "others? Consider: If you wanted to build a "terrarium" for sentient evolving life forms how would you keep them from escaping? 1. Make the distances really really big 2. Put a speed limit in the environment Rolled up with the Fermi paradox this simulation has "smelled fishy" to me for some time. :)
Or 3. Don't give humans capabilities to see them. Hell, I'd go even further, what if the "others" are already living on our planet, but we can't see them?