five observables
The “five observables” is a set of concepts used by UFO/UAP researchers – including Hal Puthoff and staff members of To The Stars Academy – to describe recurring, physically hard-to-explain characteristics of unidentified aerial phenomena.
The term “five observables” was popularized primarily by Luis Elizondo, a former Pentagon official. By his own account, Elizondo developed it with his team in the UAP investigation program called AATIP and made it public after his resignation in 2017; the concept was spread widely by the History channel's 2019 series Unidentified. The list is meant to summarize which physical characteristics regularly recur in UAP cases documented on the basis of pilot and instrument observations.
##The five observables
According to the most frequently cited list, they are the following: lift without visible engines, wings or control surfaces; sudden, almost instantaneous acceleration that is not accompanied by visible inertial effects; hypersonic speed without a sonic boom or heat signature; low radar and optical observability; and unobstructed movement between different media – air, water and possibly space – the so-called transmedium capability.
##Origin and use
The concept is linked to the AATIP/AAWSAP program, which ran from 2007 to 2012 and in which other researchers, including physicist Hal Puthoff, also took part. The list was later also used by To The Stars Academy and other advocates of the subject to illustrate that, in their view, some sightings go beyond the limits of known aviation technology. Physicist Kevin Knuth and others have also tried to refine the categories from a scientific standpoint. The US intelligence community's 2021 preliminary UAP report mentioned 18 of 144 examined sightings in which the objects displayed unusual flight characteristics, but added that these could also result from sensor errors or misperception.
##Official and skeptical positions
The Pentagon's UAP office, AARO, acknowledges that unexplained cases exist, but has not confirmed that these characteristics would prove real, unknown physical principles. According to skeptical researchers, a large share of the phenomena can be explained by instrument errors, perceptual distortion or misidentification of known aircraft. In the case of one of the best-known Navy videos, GoFast, AARO concluded that the object's apparent high speed is a parallax effect resulting from the aircraft's motion, while the “rotation” in the GIMBAL video was explained by Mick West and others as the movement of the camera gimbal.