Journal Article 1 Mention
W(h)ither the Drake equation?
Mark J. Burchell•2006
Top 21% · 79th Percentile
59 citations · Astronomy and Astrophysics

TLDR

We may soon learn whether life exists elsewhere by looking, even if no alien civilization ever contacts us. Some parts of the famous calculation are becoming measurable, but others remain impossible to know without observing many societies.

Summary

1 Study Aim

The study reviews the Drake equation, a formula for discussing how many detectable intelligent civilizations might exist in our galaxy. The author asks how advances in astronomy have changed its usefulness and whether contact is still the most important question. The calculation is becoming more useful for describing space, but human-like societies remain impossible to predict.

2 Study Design

The author conducts a conceptual review of the Drake equation and developments in astronomy and astrophysics. The paper examines each term according to whether observations can measure it or whether it concerns social behavior. It also considers astrobiology, the study of life throughout the universe, as a broader framework. The review uses no new experiment, survey, or sample of societies. The paper compares what scientists can now observe with what they can only discuss or guess.

3 Findings

The author argues that the Drake equation is not a strict mathematical equation, despite its multiplied terms. Astronomy can now measure, or soon measure, many physical factors involving stars and planets. However, terms involving intelligent societies, communication, and survival remain unknowable without observing multiple societies. The study also finds that astrobiology has broadened the central question from communication to life itself. Future observations might detect nearby life directly, producing major consequences even without contact with an intelligent civilization. We may discover life beyond Earth before we ever exchange messages with another society.

Abstract

For over 40 years the formalism known as the Drake equation has helped guide speculation about the likelihood of intelligent extraterrestrial life contacting us. Since the equation was formulated there have been significant advances in astronomy and astrophysics, sufficient to merit a review of the significance of the Drake equation. The equation itself is as a series of terms which, when combined, allow an informed discussion of the likelihood of contact with an alien intelligence. However, whilst it has a mathematical form (i.e. a series of terms multiplied together to give an overall probability) it is best understood not as an equation in the strictly mathematical sense. Some of the terms have a physically quantifiable, numerically based meaning (e.g. obtainable from astronomy) and some are more social in content in that they describe the behaviour and evolution of societies and thus are more social science in nature and not truly estimable without observation of a set of societies. Initially, almost all the terms had to be estimated based on informed guesswork or belief. However, in the intervening period since the early 1960s, many of the a priori scientific terms which were themselves initially so uncertain as to require estimation by guess work or belief are now, or will soon be, directly measurable from current or planned astronomical projects. This leaves the non-scientific terms as a distinct class of their own, still subject to analysis only by discussion. Thus observational astronomy has nearly caught up with parts of the Drake equation and will soon quantify the purely physical science parts of the equation. The social parts (concerning intelligent societies, etc.) are still a priori unknowable. In addition, the growth of the subject called astrobiology (i.e. the study of life in the Universe) has developed so fast that communicating with intelligent life is now increasingly seen as just one small part of a much larger discipline. The knowledge as to whether there is life per se (apart from on Earth) in our galactic neighbourhood may be obtainable in the near future directly from observation. Such knowledge will have a profound impact on mankind and will be obtained without the form of communication envisaged by the Drake equation.

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