Reception
The two papers were critically received by the scientific community.
Rejection of preprints by arXiv
ArXiv declined to archive preprints of either paper, asserting they lacked "sufficient or substantive scholarly research". [12] [13] Villaroel reacted to this decision on Twitter, writing "Empirical results, peer review, and publication in high-quality journals are no longer enough to satisfy the gatekeepers". [14]
Initial skepticism by scientists
Scientific American noted that there were many simpler explanations, and that this provided an opportunity for UFO skeptics and enthusiasts to see how extraordinary claims are scientifically tested. [12] Michael C. F. Wiescher suggested Villarroel, Bruehl, and their coauthors had actually been observing debris that resulted from earlier nuclear tests and that would give the appearances of "bursts of radiance" when seen through a telescope. [12] SETI's Eliot Gillum noted that Villarroel's results could be explained by meteors that flew directly towards the telescope's view, instead of perpendicular to it, resulting in the appearance of specks of light as opposed to streaks. [12] Sean M. Kirkpatrick stated the results were probably the result of either solar flare radiation or high-altitude balloons. [12]
Princeton University's Robert Lupton, a research astronomer, commented he was left unimpressed with the strength of the statistical analysis undertaken in Villarroel and Bruehl's research. [15] Nigel Hambly, who specializes in digitized optical sky surveys, [15] suggested that examining the actual plates—instead of digital copies as Villarroel and Bruehl did—might result in a different conclusion, and that "there's no shame in being wrong". [12] Writing on his personal website, Adam Frank applauded the researchers' effort at peer review of the two papers, though cautioned that "getting your paper published in a peer-reviewed quality journal does not make it right". [16]
Other critics noted that the 1950s were a "golden age" of UFO sightings and the results correlating the appearance of the artifacts with UFO reports could be attributed to observation bias. [17] The Center for UFO Studies maintains a historic database of UFO sightings (UFOCAT) which was used by Villarroel and Bruehl. [6]
Knuth, et al. rejoinder
In a preprint of a rejoinder paper, Kevin Knuth; Wesley Andres Watters, a physicist at Wellesley College; and Laura Dominé, a physicist at Japan's National Institute of Information and Communications Technology, rejected the conclusions of the Villarroeal et al. papers, noting what they identified as several issues, including that "even tentative identification of optical flashes required close microscopic analysis, which B. Villarroel et al. did not perform", that the paper contained "inconsistent statements concerning data preparation", that the papers used "circular reasoning and tautological claims" to draw their conclusions, and that the papers employed datasets that had "not been validated in ways that are necessary for their use in a scientific study". [18]