Astrobiology Project

Joves i Ciència 2019

Drake equation

Frank Drake worked out, in 1961, a tentative equation to estimate the probability to contact an extraterrestrial civilisation. 

The good old Drake

The good old Drake

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Number of civilisations that are able to contact us.  

Drake equation

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Star formation rate in the Milky Way.

Credit: JiC 2017

Drake equation

Fraction of stars that have planets

Number of habitable planets in each star with planets.

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Drake equation

Fraction of habitable planets that actually develop life.

Abiogenesis: creation of life based on inorganic material. 

 

We don't have proof of more than one abiogenesis on Earth. However there could have been several abiogenesis even though only the descendents of one could survive, after competing against the others. Also life on Earth could be of extraterrestrial origin... 

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Drake equation

Fraction of planets with life that develop intelligent life.

  • Pessimistic estimation: Intelligent life is very unlikely, since there is only one intelligent species on Earth, out of several millions of species.
  • Optimistic estimation: since the complexity (?) of life grows with time, the fraction f_i tents to 1 with time. In other words, intelligent life is unavoidable at long scales. 
N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Drake equation

Fraction of civilisations that develop detectable technology, i.e., radio.

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Drake equation

Lifetime of a civilisation that has reached the technology adolescence.

N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L

Drake equation

A long way to a new home

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