The Drake Equation was created by Frank Drake and presented to a group of individuals. Later, when the Search for Extraterrestrial Intelligence (SETI Institute) was founded, this and the Fermi Paradox would be used to contemplate the prevalence of other intelligent species beyond Earth and contrast it with the observations produced so far. The Drake equation is used specifically in reference to intelligent life. It also cannot take into consideration factors we don’t consider when typically searching for life. Part of this is because we tend to look for situations similar to our own, but a second part is that we cannot know or take into account things that we have no evidence for or that we have never thought could happen.
The odds of intelligent life only existing on Earth is 1 in 1022. If the odds of life arising and becoming intelligent is larger than this, there is a high chance we are not the only intelligent life in the Milky Way.
N = R* * fp * ne * fl * fi * fc * L
So, let’s break this down.
N is the number of civilizations we could potentially detect from Earth.
R* is the number of new stars generated each year that form and would be capable of supporting life. This fluctuates but can be determined. It has been suggested that we should be focused on observable stars in the Milky Way specifically, rather than all stars in the Milky Way. This would give us approximately 0.80.
The variable fp is the probability a star has planets. Since most stars have planets, this factor could technically be left out since many people use 1.00.
Next is the ne factor. This is the average number of planets stars have that are capable of supporting life. This is thought to be one out of every 5 planets. Since moons may also be capable of supporting life, it has been suggested that this should be changed to habitable objects.
After that is fl, which is the average number of those planets that actually host life. This is the first variable which we cannot determine an answer for.
We have no reference to determine fi, the amount of life that is intelligent, either since we are the only intelligent life we know of.
We also cannot determine fc, which is the amount of that life that can produce signals we could detect, due to a point of reference.
Lastly, we have L, how long the signals are produced for. We don’t know anything about other intelligent life or the life spans of intelligent civilizations, so we have no idea if there are any alive out there or how long they could produce a signal for.
To be clear, the Drake equation does not calculate the probability of finding life as a whole, it specifically calculates the number of intelligent, communicating life beyond Earth. It is primarily used for theoretical purposes, especially since we don’t have reasonable estimates for some of the factors that it considers.
Bibliography
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Shostak, S. (Jul 2021). “Drake Equation.” SETI Institute. Retrieved Dec 29, 2021, from https://www.seti.org/drake-equation-index
Sierra, L. (Aug 2021). “Are we alone in the universe? Revisiting the Drake equation.” NASA Exoplanet Exploration. Retrieved Dec 29, 2021, from https://exoplanets.nasa.gov/news/1350/are-we-alone-in-the-universe-revisiting-the-drake-equation/
Whitt, K.K. and Byrd, D. (May 2021). “Happy birthday, Frank Drake.” EarthSky. Retrieved Dec 30, 2021, from https://earthsky.org/human-world/drake-equation-frank-drake-seti/
Whitt, K.K. and Byrd, D. (May 2021). “Updating the Drake Equation.” EasthSky. Retrieved May 28. 2022, from https://earthsky.org/human-world/drake-equation-frank-drake-seti/
Mysteries of Space 