The Drake Equation
Does alien life exist? Are there other intelligent beings somewhere in the universe? Are we truly alone in the universe? These seemingly existential questions and thought experiments have been mathematically quantified in the Drake equation which was created in 1961 by Dr. Frank Drake. The original intent was to try and stimulate scientific thought and debate on the question of extraterrestrial life.
N = R * fp * ne * fl * fi * fc * L
N = The number of broadcasting civilizations.
R = Average rate of formation of suitable stars (stars/year) in the Milky Way galaxy
fp = Fraction of stars that form planets
ne = Average number of habitable planets per star
fl = Fraction of habitable planets (ne) where life emerges
fi = Fraction of habitable planets with life where intelligent evolves
fc = Fraction of planets with intelligent life capable of interstellar communication
L = Years a civilization remains detectable
Essentially any number except zero is acceptable for any of the terms since we exist, proving that intelligent life has happened at least once in the universe. The initial estimates were the following.
R = 10
fp = 0.5
ne = 2.0
fl = 1.0
fi = 0.01
fc = 0.01
L = 10000
The equation then predicts 10 planets with intelligent life somewhere in the Milky Way Galaxy. Higher estimates put the number as high as 40,000 planets with intelligent life, quite a large margin, if you ask me. You can play around with the Drake equation here.
You might be thinking why I am bringing this up now, but I recently saw a clip from Dragon Ball Super where the Supreme Kai mentions that there are only 28 planets with intelligent life on them in the entirety of Universe 7 (our own universe), which seems a bit low, if we assume 1 intelligent species per planet. The Drake equation only looks at the possibility of life in our own galaxy and not the entire universe, but it is simple enough to take the number of galaxies in the universe and multiply it by the Drake equation prediction and we can get an estimate on the number of intelligent species out there in the universe. The latest study by the Hubble space telescope shows that there are 2 trillion galaxies in the known universe. This means that there could be up to 20 trillion intelligent species in the known universe.
Given that Universe 7 only has 28, just what was the Supreme Kai doing? He does have a potential excuse in Majin Buu, who went on a rampage of destruction wiping out numerous planets. If we compare Majin Buu to an extinction level event, then we can see just how many intelligent species were destroyed. The worst extinction event on Earth was the Permian–Triassic extinction, which killed off 96% of all species on the planet. If Majin Buu killed off 96% of all intelligent species in the universe, then there should still be somewhere around 800,000,000,000 billion intelligent species in the universe, give or take a few billion. Sadly then, Beerus was completely right for calling the Supreme Kai out on not doing his job.
The Dragon Ball Franchise severely undercut the number of species in the universe. Are there any anime that get it right, or at least closer? With the addition of Macross Delta to the Macross Universe (which covers just the Milky Way Galaxy), there is one anime franchise that I know of, that is doing a better job regarding the Drake equation. When Macross first began you had the humans, Zentradi, and the extinct protoculture. Macross 7 added the Protodeviln (haven’t seen Macross 7, but I know enough that they could be excluded if you wanted to be technical). Macross Frontier added the Vajra. The most recent entry into the franchise, Macross Delta, adds the Zolans, Ragnans, Windermereans, and Voldorians. This brings the total number of intelligent species in the Galaxy to nine, which is more in line with Drake equation predictions.