Astrobiology research is revealing the high specificity and interdependence of the local parameters required for a habitable environment. These two features of the universe make it unlikely that environments significantly different from ours will be as habitable. At the same time, physicists and cosmologists have discovered that a change in a global parameter can have multiple local effects. Therefore, the high specificity and interdependence of local tuning and the multiple effects of global tuning together make it unlikely that our tiny island of habitability is part of an archipelago. Our universe is a small target indeed.
– P. 625, The Nature of Nature
Perhaps, the less we know, the easier it is to imagine “THEY are out there” – without the undue burden of details.