It seems like the whole article tries to disprove the Headline…
IANA Radio Astronomer, and I of course don’t know the ins and outs of what interference they have to regularly discard and the ability of certain kinds of signals to be detectable from 4 LY away, but this conclusion, on the face of it, seems lacking:
Specifically, when it comes to BLC1 and its roughly 60 brethren, the signals are spaced at regular frequency intervals in the data, and these intervals appear to correspond to multiples of frequencies used by oscillators that are commonly used in various electronic devices, Sheikh explained. This suggests these signals come from human technology, although the scientists were unable to identify their precise source.
Might not non-human civilizations ALSO use such frequencies, since they are artifacts of useful technology? This is akin to saying, “We heard what sounded like speech in an unknown language, but since humans use speech, we decided it couldn’t be aliens. Because no one else would ever use speech.”
Odd that you’d specifically be looking for the radio artifacts of a technological civilization like your own, and then when you find radio artifacts of a technological civilization like your own, you decide that the existence of such evidence means that you found nothing.
From the article:
“Second, the researchers determined whether the remaining hits appeared to come from the direction of Proxima Centauri. To determine this, the telescope pointed in the direction of the star and then pointed away, repeating this “on-off” pattern several times.”
This signal passed this test…with no explanation in the article on how an accidental terrestrial signal could do this. These aren’t the droids you’re looking for…
I don’t know precisely what oscillators they’re referring to, but the frequencies of most oscillators depend on their shape and size, and those are chosen to get frequencies people want. And people want them because they match some standard, so they’ll work will all sorts of other electronic bibs and bobs that were designed for those frequencies. So, while aliens likely would have their own techs with their own standard frequencies, there’s no reason to expect they’d be the same frequencies as ours.
And some human frequencies are so common that astronomers just discard them entirely without even trying to figure out the sources.
I thought the point was that there’d be no reason to expect they’d be very different…I think when we figure out how to detect neutrinos better, we might find more alien technosignatures.