Abstract
Several exoplanets have been discovered to date, and the next step is the search for extraterrestrial life. However, it is difficult to estimate the number of life-bearing exoplanets because our only template is based on life on Earth. In this paper, a new approach is introduced to estimate the probability that life on Earth has survived from birth to the present based on its terrestrial extinction history. A histogram of the extinction intensity during the Phanerozoic Eon is modeled effectively with a log-normal function, supporting the idea that terrestrial extinction is a random multiplicative process. Assuming that the fitted function is a probability density function of extinction intensity per unit time, the estimated survival probability of life on Earth is sim0.15 from the beginning of life to the present. This value can be a constraint on f_i in the Drake equation, which contributes to estimating the number of life-bearing exoplanets.
Highlights
Several exoplanets have been discovered to date, and the step is the search for extraterrestrial life
N, the number of civilizations in our Galaxy with which communication might be possible; R∗, the mean rate of star formation averaged over the lifetime of the Galaxy; fp, the fraction of stars with planetary systems; ne, the mean number of planets in each planetary system with environments favorable for the origin of life; fl, the fraction of such favorable planets on which life does develop; fi, the fraction of such inhabited planets on which intelligent life with manipulative abilities arises during the lifetime of their local sun; fc, the fraction of planets populated by intelligent beings on which an advanced technical civilization arises during the host star’s lifetime; L, the lifetime of the technical civilization
This paper introduces a new approach to estimating the probability that life on Earth has not gone extinct since the birth of life, fi,⊕
Summary
Several exoplanets have been discovered to date, and the step is the search for extraterrestrial life. The fossil record in the Phanerozoic Eon, which covers 540 Myr to the present[22,23], indicates that a histogram of extinction intensity can be well modeled by a log-normal distribution. This log-normal distribution of extinction was converted into a cumulative probability that life on Earth survives up to the present, fi,⊕ , by “continuing to win the lottery of extinction” since its birth.
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