When?

Social science can be empirical and produce results that are both highly correlated and valid.

Pilots that are cleared to carry, and potentially deploy, sophisticated weapons payloads are considered to be among the most rational, capable and intellectually stable people. Eyewitness testimony from these pilots must be carefully considered.
Further, significant amounts of descriptions of unidentified aerial phenomena from other credible people should not be dismissed. Consider that the stigma around the subject of “UFO’s” is so potentially damaging to these witnesses, yet they still make their claim despite this intense social pressure. Certainly this combination of the sheer amount of credible witnesses despite the socially discouraging stigma indicates that a significant amount of people truly “believe ” that they have seen something that is not easily explained.

Clearly, significant amounts of people have seen objects that cannot be identified. So, unidentified aerial phenomena “exist”. We seek a scientific explanation that this aerial phenomena is/are “real” or can/could be explained and/or identified. But potential explanations cover a wide array of possibilities.

Our civilization’s best estimates indicate that the size of our Universe is ~93 billion light years in diameter. Surely, the vastness of our Universe contains intelligent life.
So, what is the likelihood that our space and our time are experiencing more than one form of intelligent life?