[Quoting Beatriz Villarroel] "If you want to investigate UFO cases using the scientific method, I highly recommend reading analyses produced by 3AF-Sigma2 in Paris."
Sigma2 is a subgroup of French aerospace interest group 3AF (Association Aéronautique et Astronautique de France,
https://www.3af.fr/en/about-3af/mission-6531) that is interested in UFO reports.
One of the articles on their website is "About Joint work between SIGMA2 3AF and Dr. Jacques Vallée", Nadia Tronche, 15 April 2026
https://www.3af.fr/en/news/about-joint-work-between-sigma2-3af-and-dr-jacques-vallee-2519;
External Quote:
I would like to pay tribute to Dr. Jacques Vallée for the work carried out jointly with the SIGMA2 Technical Commission of 3AF. In particular, we performed analyses of material samples and a study of the radiation emitted by a pulsed light sphere (the Haynesville case, 1966, Louisiana, USA), on which we co-authored an article published in the journal Progress in Aerospace Science with the active support of Dr. Jacques Vallée and members of 3AF SIGMA2 (1) (Luc Dini, Geoffrey Mestchersky).
The paper Tronche refers to is "Estimates of radiative energy values in ground-level observations of an unidentified aerial phenomenon: New physical data", Jacques F. Vallée, Luc Dini , Geoffrey Mestchersky 2025, Progress in Aerospace Sciences Vol. 156.
Its abstract and some other extracts are viewable via Science Direct
https://www.sciencedirect.com/science/article/abs/pii/S0376042125000247
What appears to be a pre-publication draft is viewable via 3AF at
https://www.3af.fr/global/gene/link...-aerial-phenomenon-new-physical-data.pdf&fg=1, PDF below. The text appears to be identical to the published extracts of the published paper viewable at Science Direct.
The researchers estimate the energy output of a claimed glowing spherical UFO based on its estimated distance from some scorched bark
collected by the claimant, a nuclear physicist, Louie A. Galloway. Another source they use is the claimant's estimate of the distance at which the glow of his car's headlights was "overwhelmed" by the light from the claimed sphere. I don't find these convincing as reliable methodologies.
One of the bark samples had an elevated level of caesium 137. The authors consider possible sources, including accidents at US nuclear power stations. But having dwelt on Galloway's profession earlier in the paper, they seem to forget it here. Maybe he, or a colleague/ contact, had access to trace amounts of caesium 137 and, er, accidentally contaminated the sample?
It appears there has been no study of the bark samples since 1978, a quick casual reading of the paper might suggest to an unwary reader that the 2026 authors had conducted studies (in fairness they do not claim this), they have not.
There is (as in another paper Vallee co-authored) text that implies the author
s of this paper spoke with someone (here, Edward Condon) in connection with it/ the case it refers to, when in fact the only author involved in claimed communication with Condon appears to be Vallee, many years earlier (my emphasis)
External Quote:
Following our communication with him, Dr. Condon concurred and his group undertook extensive follow-up studies...
...but Condon died in 1974, Wikipedia
https://en.wikipedia.org/wiki/Edward_Condon
There are extraordinary claims made without evidence,
External Quote:
High-energy events are not rare in the context of UFO/UAP reports. ...Among the latter effects are injuries... ... as well as long-term conditions that occasionally require hospitalization and can lead to death. Physical impact (apart from known mechanical effects) is most often in the form of light energy (many cases trigger photocells in cities and villages) and detrimental impact on irradiated plants, as in this case.
There are contradictions, at least in 3AF's pre-publication copy, from
6.6 Sample examination
External Quote:
When we examine sample A, we might expect to see only the outer surface blackened, as we know that only this side was exposed to the
phenomenon/object. This is not the case, both the outer and inner of the sample are blackened while the interior remains unaffected. It is on that basis that more accurate estimates of energy could be made...
...and from
8.3. Preliminary results and challenges,
External Quote:
The solution space is complex and currently contains multiple unknowns including: ...The extent of the charring (maybe one of the most crucial ones): without detailed information on the depth and uniformity of the charring, it is difficult to fully validate the approach or reduce the dimensionality of the problem.
If Villarroel finds analyses produced by 3AF-Sigma2 particularly convincing, that is up to her. I don't think this paper is without problems. Perhaps there are other studies she could point to that are more persuasive than this one.