The Fermi Paradox: A 10 Step Guide To Finding Aliens
7. The Drake Equation
We can take these factors, and others, and use them to calculate life in the universe. They say that for every equation you use, your readership is halved, so let's get the Drake Equation out of the way: N = R* x fp x ne x fl x fi x fc x L
Still there? Good.
This equation was formulated in 1961 by Frank Drake in an attempt to calculate the probabilities of finding extraterrestrial life in the galaxy, represented by N. It consists of all of the questions that scientists would need to answer in order to predict the amount of detectable civilisations in the galaxy and multiplies them together to get the estimate for that number.
Surely then, this equation gives us the answer to the question "Where are all the aliens at?". Well, not really, because some of it values are still uncertain, meaning that we can derive a range of answers depending on the values we put in. The first three values are relatively easy to estimate. R* = The yearly rate of star formation in the galaxy, fp = the fraction of those stars with planets, ne = the number of planets in a solar system suitable for life.
The last four values are more difficult as we don't really have a clue what they are. fl = is the number of planets on which life actually appears, fi = the fraction of that life that develops intelligence, fc = the fraction of intelligent life that develops technology to send signals into space and L = the length of time those civilisations transmit those signals for.
Because these values are so open to debate, scientists have come up with wildly varying answers using the equation. When Drake first came up with the equation, his inputs into it yielded a result of anywhere between 1000 and 100,000,000 civilisations, modern estimates that take into account the latest scientific advances are even less reliable, with estimates anywhere between less than one to 280,000,000 depending on your interpretation of the science.
Not exactly conclusive, so how else can we figure this out?