The Drake Equation: Mathematical evidence we're not alone.
The Drake Equation is a well-known result in the fields of xenobiology, astrosociobiology and the search for extraterrestrial intelligence.
Also known as the Green Bank equation or Sagan equation, it was developed by Dr. Frank Drake in the 1960s during his effort in trying to estimate the possibility of the number of extraterrestrial civilizations we could come into contact with, within
our galaxy. The equation allowed scientists to calculate the uncertainty of factors that determine the number of extraterrestrial civilizations.
The Drake equation states that
N = R* x fp x ne x fl x fi x fc x L
N is the number of extraterrestrial civilizations in our galaxy which we could possibly communicate with And the equation is made up of the following variable factors:
R* - The rate of star formation in our galaxy
fp The fraction of stars which have planets
ne - The average number of planets that can
potentially support life per star that has planets
fl - The fraction of the above which actually develops
life
fi - The fraction of the above which actually develops
intelligent life
fc - The fraction of the above which are willing and
able to communicate
L - The expected life span of such a civilization
A lot of disagreements occurred due to the speculation of existence for the above parameters, but the values were determined as the following by Drake and his team
in 1961.
R* = 10/year
fp = 0.5
ne = 2
fl = 1
fi = fc = 0.01
and L = 10 years
The values of R* and fp were not in as much dispute as the rest of the values. ne hadnt much issues before but the discovery of various gas giants in close orbit with their stars has reduced chances that other life-supporting planets will commonly survive the
creation. Most of the stars are known to be red dwarfs, which have little of UV rays that assists the evolution of our life on Earth. In fact, they are known to flare violently and possibly erode planetary atmospheres by creating the occasional outbursts which
we know to be non-conducive for life.
The value of fl seems to be quite high now as conditions on Earth have shown that life can almost begin upon the gathering of the crucial factors, meaning that abiogenesis happens easily once conditions are right. However, the evidence is limited and this term is still in dispute. If the verification of life on Mars is successful, it would be easier to determine the accuracy of this term, since the conclusion is that life on Mars is developed independently.
Obviously in the equation, fl, f and L are only a little more than guesses and these terms closely affect each other. fl has been strongly influenced by discoveries that the solar systems orbit is circular at a distance that remains out of the spiral arms for
hundreds of millions of years causing evasion from radiation from the novae. In addition, while life was developed very soon after the formation of Earth, research suggests that other special conditions were necessary for this occurrence. Research into
extinction events or scenarios such as Snowball Earth has concluded that life on Earth is fragile. Thus, this questions that life on Mars may have been formed but its existence was ceased. All the above factors strongly affect the inference of the terms in the equation.
Famous astronomer Carl Sagan speculated that all the terms, with the exception of lifetime of a civilization are relatively high, and the factor influencing the existence of small or large numbers of civilizations is closely related to the civilization lifetime. In his case, the Drake equation became a motivating factor for his interest in environmental
issues and the dangers of nuclear warfare.
Often, the mention of the Drake equation would bring about the Fermi paradox. This is named after Enrico Fermi who first publicized the subject. The conflict arose from how fairly plausible values plugged into the equation often garner the results that N is
generally often >>1. This disagrees with the current situation that there is only one observed civilization in the universe where N = 1.
According to Enrico, he suggests that our understanding of what may be a conservativevalue for some of the terms may be overly estimated or there could be other existential factors that we have overlooked and this suppresses the development of intelligent space-faring life.
In situations where N << 1, observers believe that this is still acceptable due to the anthropic principle; no matter how low the probability that any given galaxy will have intelligent life, the galaxy we are in will have at least one intelligent species by
equation.
At the end of the day, N is affected by the numerous terms in the equation, whether it is optimistic assumptions or negative, so far, there is no solid evidence to purport that any particular persons calculations or value of terms used is the most
accurate.
