The estimate changes when civilization lifetime changes
Present concrete inputs and the intermediate reasoning steps that connect them to a conclusion, including a revealing wrong move or alternative where available.
Cosmos
Carl Sagan · 70 weeksThe estimate changes when civilization lifetime changes
SHORT SOURCE EXCERPT“make your own choices and see what implications your alternative suggestions have”
Sagan defines the factors in an estimate of communicating civilizations, comments on their uneven uncertainty and follows their combination. He then contrasts short-lived technological civilizations with a survival scenario, producing sharply different outcomes from the changed assumption.
The calculation makes uncertainty inspectable and connects the search for other civilizations to the survival question that leads into the final chapter. Inviting alternative estimates gives the reader a specific place to examine the reasoning.
The source in context.
The decoding of an unfamiliar written language introduces the problem of recognizing and understanding another civilization. The Drake equation makes estimates and uncertainty explicit, while historical encounters complicate expectations about contact.
Open this chapterWhat this example supports
The calculation makes uncertainty inspectable and connects the search for other civilizations to the survival question that leads into the final chapter. Inviting alternative estimates gives the reader a specific place to examine the reasoning.
Its limit
The numerical choices belong to the book’s historical discussion. A scenario calculation is not evidence for its uncertain inputs or the existence of the estimated civilizations.
Source & edition
Carl Sagan, Cosmos; supplied English text, introduction dated May 1980, precise edition unverified.
Supplied text, lines 3089–3155. The short quotation is checked against the source.
The completed whole-source AI draft supplied the broad architecture and candidate observations. This Codex editorial pass checked the original contents, all thirteen main chapter headings and boundaries, introduction and appendix headings, selected chapter opening/ending contexts, and the full retained example contexts. Existing pattern definitions and already reviewed examples were checked before writing this record. This was a targeted source-checked editorial pass, not an independent whole-book rereading.
Supplied English text with an introduction dated May 1980 and later biographical front matter; precise edition unverified.