The single most intriguing question faced by mankind is whether we are alone in the universe.  In 1961 astronomer Frank Drake (b. 1930) posed this question in terms of an equation which bears his name.

The genius of astronomer Frank Drake (b. 1930) was to take the complete unknown of the number of extant communicative extraterrestrial civilizations and break it up into a sequence of factors, each of which can be estimated.

The result was the Drake equation.  Drake devised it in 1961 to create an organizing agenda for a conference he had organized to discuss the possibility of contact with extraterrestrial civilizations at Green Bank, West Virginia, the site of the National Radio Astronomy Observatory.  Using its 85-foot diameter radio telescope, he had just completed Project Ozma, the first attempt to detect such signals, generating worldwide interest. 

The factors are the number of technical, communicative civilizations existing at any time, the rate of star formation currently and in the recent astrophysical past, the fraction of those stars which have planetary systems, the number of planets around the star within its habitable or ecological region, the fraction of those habitable planets on which life evolves, the fraction of those planets on which the life develops intelligence, the fraction of those planets on which the intelligent life develops the technology for interstellar communication, and, the most unknown, L, the longevity of  the communicative civilizations.  The Drake equation provides the factors in the order of that in which we have the most confidence to that in which we have the least confidence.   Various astronomers, including Drake, have provided estimates for the factors, but in some cases the estimates vary widely.  The only means of estimating L is by examining our own civilization.  Then the number of extraterrestrial communicative civilizations, N, can be found by multiplying all the factors together.

Leslie M. Golden of the Center for Computational Astrophysics, who was a student of Drake at Cornell University, has now in effect created a joint mind from these astronomers by a mathematical procedure called Monte Carlo multiplicative analysis.  In this, a distribution of each factor is defined and each is randomly sampled many times.  The product of those samples yields a value for the coefficient of L.  The distribution of those products, the coefficient of L in the Drake equation, can be examined.

Golden found that the mean of the distribution of the coefficients is 0.85 (±1.28) 1/years.  Multiplying by chosen values for L then provides the number of technical, communicative civilizations existing now.  If, for example, the longevity is a paltry 1000 years, then only 850 such civilizations exist in our Milky Way galaxy of 100 billion stars.  If, on the other hand, mankind finds a way to exist peacefully with himself and the Earth, perhaps L is 1 million years and N is 850,000 civilizations.  The more civilizations that exist, the better the chances that one is sufficiently nearby to establish communication.

The paper, “A Joint Mind Consideration of the Drake Equation in the Search for Extraterrestrial Intelligence,” was published in March, 2021, in the peer-reviewed journal Acta Astronautica.

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