Drake Equation : Are We Alone in the Universe?

 Frank Drake hosted a meeting on “search for extra-terrestrial intelligence” on detecting radio signals transmitted into space by civilisations orbiting other stars. The equation was formed in 1961 based on Frank Drake’s equation. It is a probabilistic method of approximating the existence of active, communicative extra-terrestrial civilisations in the Milky Way Galaxy.

 

Equation Explainer

N = Number of detectable civilisations in the Milky Way Galaxy

R = Rate of star formation [N.B. – Astronomers estimate these number is about 1]

f_p = fraction of these that have planets 

[ N.B. 1 = 100 percent, 0.25 = 25 percent etc. At least half of all sun-like stars have planets. Most stars are too small to gravitationally support a planetary system, while some others life span is too short]

n_e = Number of earth like planets (Planets with water within it’s planetary system) 

[N.B. – For solar system, this is at least 1 – planet earth. But maybe more, if Europa or other moons have ocean

f_l = Fraction of earth like planets where life develops.

 [N.B. – if you think earth-like planets produce life, the value is 1. If you 1 in 10 planets produce life it is 0.1]

f_i = Fraction of intelligent life supporting sites 

[Note: For these purposes, intelligence is defined as having a symbolic language —mathematics, or English or Japanese — since language is required for communication. If you think every planet with life produces intelligent beings, sooner or later, this estimate would be 1. If only one percent do, then estimate would be 0.01.]

 

f_c = Communication developing life sites 

[N.B.- There could be intelligent beings who haven't yet invented radio telescopes (We humans belonged to this category until the 20th century). Or there could be others who have the means to communicate but don't — perhaps because they are not interested or fear that they might endanger themselves by advertising where they live. ]

L = Lifespan of communicative civilisation 

[N.B. - Humans have been communicative for less than 100 years. Do you think we, or the average intelligent species remains willing and able to communicate with other star systems for only a century? A thousand years? A million? Your guess is as good as the experts'.]

 

Dreaming of Aliens

Planets being discovered by telescopes, however, only supports minuscule number of environments suitable for life. Factors such as proximity to its star, and constituent of atmospheric gaseous environment, available sources of energy etc. plays a crucial part

Mirage of Life

 

A catalog of 53 habitable exoplanets has been confirmed as of 2018 with potential for life. Out of those 13 are more likely to be habitable with microscopic life to complex cellular species. 

Currently there are 300 million Rocky Earth-like worlds in Milky Way around sunlike stars. The number increases if planets orbiting non-sunlike stars are included. But it gets even bigger when moons are also included as part of the equation.