How odd that "multiple sources" all started acting up, or never attracted much attention, until the 1940s.
And this because of the tests we began to work in earnest with the ex Nazi scientists around 46' and beyond. Strange lights in the skies, "saucers", all a phenomenon of the 50's and 60's drive-in theatres and nothing more.
There is a plethora of evidence which points to ET even if it (i.e. what's known to laymen) doesn't conclusively prove it. If all that evidence doesn't impress you, you're either unaware of it or biased against the ETH. For all its apparent flaws, the ETH is still the best explanation and will likely remain that way.
LOL! "We have proof, just don't look at it too closely, because when it truly stands up to scrutiny, it sorely lacks in anything but theory and nothing more."
Over 60 years now and no magic rubber metal, no crashed saucer, no little gray alien bodies to see....NOTHING but Mork wannabes who haunt the forums on a nightly basis panning God and spewing forth nonsensical "doesn't impress you" and "unaware" BS.
Of course it is, in theory. If it can be shown that the odds against life appearing, even on an earthlike world, are billions to one against, so life here was an incredible fluke, virtually impossible to replicate elsewhere, that would do it in. Or, if all landed saucer, humanoid sighting, crash retrieval etc cases were ever proven to be some kind of elaborate scam, by the government, or some conspiracy, that too would finish it.
No it's not falsifiable to people such as Trajanus because of the limited depth of perceptive reality utilized by the sheer disdain for anything remotely different than E.T. and only E.T. You could spend a millennial time frame with research, actual govt. findings, etc. and of course:
A. The govt. is in on it.
B. The research was tainted by naysayers
C. The proof is in the many eye witnesses and that should be enough because I, "Trajanus" say so!
It makes at least one prediction we may test before long--habitable extrasolar planets exist, in older star systems.
And what would this prove? That God made other planets with other life forms? That other planets can sustain life? What possible intention could this allow for in the context of an intelligent extraterrestrial life forms unless we actually found that life form's trace history or some archeological sustenance.
And even so, this proves ABSOLUTELY nothing when it comes to E.T. visiting or crashing to earth in 1947. Their just might be intelligent life out there in the universe....But just because some creative Hollywood Directors played up on the saucer/man from space idea after the Roswell debacle, and then the world became hysterical as to the idea that little gray aliens have somehow visited us and been here all along, is just ridiculous.
Keep the study of this phenomena to a scientific investigatory reasoning only, and that is to record the eyewitnesses, take data and observe. Show the truth (85% anomaly and 15% unexplainable, probable govt. or other) and disallow the fanciful notions of a few Martian wannabes.