“It is argued that if extraterrestrial intelligent beings exist, then their spaceships must already be present in our solar system.”

Frank J. Tipler

“[A]n intelligent species with the technology for interstellar communication would necessarily develop the technology for interstellar travel, and this would automatically lead to the exploration and/o...”

Frank J. Tipler

“[T]hat any intelligent species which develops... interstellar communication will also have... rocketry... is... a consequence of the principle of mediocrity... (that our own evolution is typical)... [...”

Frank J. Tipler

“[I]t seems likely that a species engaging in interstellar communication would possess a fairly sophisticated computer technology. ...Sagan has asserted that 'Communication with extraterrestrial intell...”

Frank J. Tipler

“I shall assume that such a species will... develop a self-replicating universal constructor with intelligence comparable to the human level—such a machine should be developed within a century, accordi...”

Frank J. Tipler