| 释义 |
Drake equation, n. Astron.
Brit. |ˈdreɪk ɪˌkweɪʒn|, U.S. |ˈdreɪk əˌkweɪʒən|, |ˈdreɪk iˌkweiʒən|
Forms: 19– Drake equation, 19– Drake's equation
[‹ the name of Frank D. Drake (b. 1930), U.S. astrophysicist, who formulated the equation in 1961 + equation n.]
An equation devised to estimate the number of extraterrestrial civilizations that may potentially be detected in our galaxy.
The equation combines a number of independently estimated factors, taking the form N = R0fpneflfcfcL, where R0 is the rate of star formation, ne the number of planets per solar system capable of sustaining life, and the factors fp, fl, fc, respectively, the fraction of stars with planetary systems, the fraction of such planets which are capable of supporting life, the fraction that develop intelligent life, and the fraction that develop an advanced civilization capable of communicating with other civilizations, and L, the lifetime of such a civilization.
1964W. Sullivan We are not Alone xvii. 264 There is no immediate way to determine the chief unknown..—that of the longevity of a technological civilisation. The other factors in Drake's equation can be assessed by experiment or observation. 1979Nature 18 Oct. 528/1 Hart pointed out that a calculation of N by means of the so-called Drake equation is essentially impossible owing to the orders of magnitude uncertainty in many of the terms. 1997Economist 25 Jan. 109/1 The Drake equation..was a string of unknown terms, and a slightly jokey reminder ever since of that state of the search for extra-terrestrial intelligence, or SETI. |