A new provocative hypothesis postulated by Social Science Prof. Robin Hanson is renewing public interest in the possibility of extraterrestrial visitation to our planet. In a scientific paper published by Prof. Hanson and colleagues, the group analyzed two potential kinds of alien civilizations inhabiting the known universe. "Quiet" and "Loud" aliens, as the collaboration taxonomized these exolifeforms, each have a different way of exploring their galactic surroundings. The "Quiet" ones, for example, refrain from exponential galactic expansion while the "Loud" ones become "Grabby' in their endeavors to expand their cosmic territory as much as possible in a relatively short amount of time, thus, making them visible across large swaths of space.
The "Quiet" aliens are of particular interest to us because they sort of conform to our current observations, or lack thereof. "Loud" or "grabby" aliens gobbling up the visible universe for themselves would in principle generate noticeable technosignatures as they transform the galactic regions under their domain. But we have yet to see evidence of this humongous cosmic land grab. The "Quiet" ones - on the other hand - have resolved not to spread beyond their planet of origin via some type of societal consensus, but nevertheless explore their galactic neighborhood in a discrete fashion.
Astrophysical evolutionary models indicate that stars born in patches of large stellar nurseries share similar characteristics. These stars can be considered siblings and may over time develop solar systems which can in principle give rise to advanced analogous civilizations. These civilizations - although now separated by large distances due to orbital drifting - will eventually develop the means to seek out their galactic siblings by surveying the sky for stars that originated in the same stellar nursery and may potentially harbor planetary bodies hosting sentient life.
If the above hypothesis is correct, Prof. Hanson believes it could explain the presence of unidentified objects on Earth. UFOs could simply be a type of "Quiet" alien scouting the cosmos for long-lost relatives and checking up on their development while keeping a low profile but occasionally making themselves known to us. If their social structure is akin to ours, then it makes sense that they would choose to reveal their presence to the echelon of planetary power, i.e., the world's military institutions, in order to subtly convey their superior hierarchical cosmic status without being overtly bellicose in their displays. Listen to the interview embedded above timestamped to the chapter on UFOs for your listening convenience, and follow the link below to learn more about the Grabby Aliens model.
Advanced aliens really are out there, and we have enough data to say roughly where they are in space and time, and when we will see or meet them.