The suggestion that artificial ET’s might more evident than biological ones is not new. Frank Tipler (before he went off the deep end) suggested in 1981 that alien civilizations might use von Neumann probes to explore a galaxy. He concluded that since we do not see such probes,
there are no ET’s in our galaxy. In science fiction the concept goes back at least to 1963, when Fred Saberhagen’s first Berserker story appeared.
Actually, almost all suggestion for SETI come down to Searches for ExtraTerrestial Technology. It will be a long time before we can find any other sign of intelligence out there.
Bok globules are another search target for sentient machines. These dense regions of dust and gas are notorious for producing multiple-star systems. At around negative 441 degrees Fahrenheit, they are about 160 degrees F colder than most of interstellar space. [Is this correct?-GTM]
This climate could be a major draw because thermodynamics implies that machinery will be more efficient in cool regions that can function as a large “heat sink”. A Bok globule’s super-cooled environment might represent the Goldilocks Zone for the machines, says Shostak.
The idea that Bok Globules might be linked to ET’s was anticipated by Fred Hoyle in his 1957 novel The Black Cloud. Early in the book some astronomers are looking at some images of the cloud (which turns out to be an intelligent and powerful life form). One of them describes it as “a fine example of a Bok globule.”