"[T]he problem of interstellar travel has been reduced to... transporting a von Neumann machine to another stellar sys…"

"It is argued that if extraterrestrial intelligent beings exist, then their spaceships must already be present in our …"

"The biologists argue that the number of evolutionary pathways leading from one-celled organisms to intelligent beings…"

"[T]he probability of the evolution of creatures with the technological capability of interstellar communication withi…"

"The basic idea... is straightforward and... has led other authors, such as Fermi... Dyson... Hart... Simpson... and K…"

"[A]n intelligent species with the technology for interstellar communication would necessarily develop the technology …"

"[T]hat any intelligent species which develops... interstellar communication will also have... rocketry... is... a con…"

"[I]t seems likely that a species engaging in interstellar communication would possess a fairly sophisticated computer…"

"I shall assume that such a species will... develop a self-replicating universal constructor with intelligence compara…"

"[T]he information to manufacture a human being is contained in the genes of a single human cell. Thus if an extraterr…"