In the article, the author says, “we know very little about ETI”, we lack evidence of ETI, also known as Fermi Paradox. The only things that we know are from our own civilization, how it arose in the last 10% of the age of Earth before it became uninhabitable, and how it has persisted. We really don’t know whether intelligent life is to be produced by evolution, or even the probability of other civilizations existence. We do not know how life began, or whether Earth is the single case. Even though the simplest explanation of why we have not found anything would be that we are simply alone, the searches conducted have only explored a very small portion of this vast universe, which still leaves the, once again, very unpredictable possibility of ETI out there.
The most common radiation emitted from our civilization is narrow radio emission. And it is believed that ETI may also emit the same type of radiation, because it seems to be the most efficient method of interstellar communication to this day, and it is also the cheapest. SETI has many other projects on nearby stars, and as technology improves, so do the searches. Searches have begun to consist of different things, such as looking for nanosecond pulses from some sort of high-powered laser, to looking for some artificial nature to the neutrinos from supernova