Harvard astronomer Avi Loeb, a believer in the possibility of alien probes visiting our solar system, and Dr. Sean Kirkpatrick, director of the Pentagon’s All-domain Anomaly Resolution Office (AARO), have collaborated on a scientific paper that is still undergoing peer review. The paper attempts to utilize physics to eliminate a number of UAP sightings that seem to involve "highly maneuverable" objects.
The co-authors find that if some UAP were indeed moving in the seemingly impossible directions and speeds that they appear to be, the friction involved should generate a visible fireball and a corresponding radio signature that would be visible via radar. The absence of all these signatures could imply that single site sensors have produced inaccurate distance measurements (and hence derived velocity), making a number of UAP sightings explicable by optical illusions or the limitations of certain equipment.
While the reports from military personnel are intriguing and motivating Loeb's work, he believes that his instruments should tell him what is truly happening. To this end, Loeb launched the Galileo Project at Harvard, which aims to utilize systematic scientific methods to evaluate the numerous UAP observations that have recently become a topic of public discussion.
However, Loeb is arguably more of a believer than a debunker. In his 2021 book "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth," he argues that the first interstellar object detected in our solar system was likely an artificial probe of some sort sent by an extraterrestrial intelligence from elsewhere in the cosmos. He has also claimed that some meteorites that have hit the Earth seem to be interstellar. The Galileo Project is preparing to recover one such object from the sea floor in the near future.