Do aliens exist?, or are we the only intelligent civilization within the universe? Human beings have had this question engraved in their minds for centuries, perhaps even millennia’s. The Drake Equation aims to answer this. The equation was coined by Dr. Frank Drake, an American astronomer and astrophysicist.1 The equation goes like this:
N = R* x Fe x ne x fl x fi x fc x L
N = The number of communicating civilizations in our galaxy
R* = Average rate of suitable star formation
fp = fraction of stars that form other planets
ne = Average number of habitable planets per star
fl = The fraction than can go on to support life forms
fi = The fraction where intelligent life forms can come into existence
fc = The fraction of civilizations that develop a technology that can be detectible from space
L = Length of time such civilizations release detectable signals into space.
A conservative take on the Drake equation
Dr. Frank Drake made various assumptions within the Drake equation. Quite a lot of those assumptions were hotly debated. For instance, Drake believed that 100% of Earth like planets would have organic life on it. We have tweaked that to a more conservative 1%. He also believed that 100% of organic life would one day mutate into intelligent life forms. We have tweaked this to a more modest 1%. The numbers within the equation are destined to change as and when we know more and more about the cosmos. That being said, lets populate the equation with the most conservative and up to date figures that are currently documented.
Decoding the Drake equation
Average rate of suitable star formation
Let us start with the first variable in this equation i.e R. It represents the average rate of suitable star formation within our galaxy. According to research, there are roughly 150 billion stars born each year in our universe,2 and our galaxy gives birth to 6 stars each year.3 Thus, R = 3
Fraction of stars that form other planets
It is believed that 40 percent of all stars in our galaxy have planets that orbit around it. Thus, Fp = 40
Average number of habitable planets per star
The equation takes 2.5 habitable planets around a star system. This figure is highly debated among astronomers. However, based on Kepler space mission data, there could be as many as 40 billion habitable planets orbiting stars within our galaxy 4.
Thus, lets take ne = 2.5. Based on this, The Milky Way galaxy has 300 billion habitable planets within it.
The fraction than can go on to support life forms
Drake believed 100% of Earth like planets would have some form of organic life on it. Let us tweak this to a more modest 1%. We shall now assume that 1% of all 300 billion habitable planets within our galaxy harbours some form of organic life. Based on this assumption we get the figure: Fl = 1%. I.e 3000000000 planets that support life form
The fraction where intelligent life forms can come into existence
Dr. Frank Drake believed that 100% of all organic life would one day mutate into intelligent life forms. Let us tweak this to a conservative 1%. We shall now assume that just a merge 1% of organic life form will one day mutate into intelligent life forms. Based on this toned-down assumption we get the figure: Fi = 1%. i.e 30000000 intelligent life forms within our galaxy
The fraction of civilizations that develop a technology that can be detectable from space
This variable points out to the percentile of intelligent beings that have developed a technology that can be detected from space. Let us take our conservative 1% figure again. Fc= 1%. I.e 300000 intelligent life forms have devised a technology than can be detectible from space
Length of time such civilizations release detectable signals into space
This variable touches on how long a life form would take before releasing a detectable single into space (much like how humans do right now) The Drake equation takes this variable’s number as 10,000,000. Thus, Fc = 10,000,000 years
Number of times civilizations could re-develop (optional)
As life span of planets go into billions of years, This variable states the likelihood that a new civilization comes up once an order civilization has withered and died. Thus Nr = 1
The final result of our toned down and conservative version of the Drake equation
Taking into account that the our galaxy is almost as old as the universe, our conservative version of the Drake equation states that we have 60 intelligent and communicating civilizations within our galaxy and 900 billion within our universe.
The final result of the original Drake equation
The article would not be complete without giving out the final numbers derived out of the original Drake equation. Here they are:
18,750,000 intelligent species don our galaxy in conjunction with 2,812,500,000 billion intelligent within our universe.5