The transcension hypothesis proposes that a universal process of evolutionary development guides all sufficiently advanced civilizations into what may be called “inner space,” a computationally optimal domain of increasingly dense, productive, miniaturized, and efficient scales of space, time, energy, and matter, and eventually, to a black-hole-like destination.
An important implications of the transcension hypothesis is as a possible explanation for the Fermi paradox—the apparent contradiction between the lack of evidence for the existence of extraterrestrials along with high probability estimates given for their existence by the Drake equation. (I have previously written about the Fermi paradox here and here.)
What all of this means is that rather than exploring the outer space of the universe, advanced civilization explore their inner space and eventually disappear from our view. And this is why the SETI Institute hasn’t found evidence of extraterrestrial intelligence. This two-minute video explains this clearly.