To date, nobody’s bothered to call.
Is it something we said?
One possibility is that we’re alone, or at the very least, the only intelligent civilization with a Zip code in the Milky Way galaxy. (Read "The Hunt for Life Beyond Earth.")
And then, there’s the morbid alternative: Intelligent life periodically emerges on other worlds, but has an unfortunate tendency to self-destruct.
Sadly, it’s not implausible, given the devastation we’ve wrought during our relatively brief span as the dominant species on this planet.
That’s why a trio of scientists recently published a guide to help astronomers detect alien apocalypses—whether it’s the chemical signature of a world filled with rotting corpses, the radioactive aftermath of nuclear warfare, or the debris left over from a Death Star scenario where an entire planet gets blown to bits.
Call it SEETI, the Search for Extinct Extraterrestrial Intelligence.