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This equation was formulated for The Green Bank meeting by . It was at this meeting SETI (Search for ExtraTerrestrial Intelligence) was established as a scientific discipline. The Drake Equation has a singular and interesting purpose, to estimate the odds of the existence of other intelligent civilisations in the Milky Way galaxy that are capable of announcing their existence by using detectable signals. Carl Sagan explains what this equation means for us in this clip fromCosmos: A Personal Voyage.
Hidden within the Drake Equation is a cautionary tale. According to our best educated guesses, out of the billions of planets that exist or have existed in the Milky Way, there could be as little as ten or as many as millions of other intelligent civilisations who have been able to send signals out into deep space. But if there have been millions, where are the signals? Why have we found nothing apart from the brief and unresolved 1977 'Wow!signal' in the last fifty years? Perhaps there are far less than millions, or perhaps many of these potential civilisations destroyed themselves within a few decades of achieving the ability to send these messages, depriving other fledgling civilisations of their knowledge and expertise. Furthermore, how many signals could we have missed during the passage of millions of Earth years before we were able to build receivers? When it comes to detecting radio signals, only a small window of opportunity is available for civilisations to connect due to the vast distances and (potentially) different rates of evolution, making the chances of missing each other high.
Despite these caveats, it is still possible one day we might detect a stable transmission sent from a civilisation thousands of light years away - signals sent while we were still perfecting the art of cave paintings. On that day, scientists would gather around to listen to the strange new signal and the best minds would commit their energies to decoding it, astronomers would mark the location of origin, and give it a name. We could feel comfort in the knowledge we are not alone in the universe after all. We could feel hope and excitement at the possibilities suddenly available to us, we could dare to think things we never permitted ourselves to think before. Carefully we begin to prepare our response when as abruptly as the signal came into our lives it stutters into silence. We target their system, we listen carefully, but there is nothing. They are gone. We are alone once more.
So far as we know, many planets in the Milky Way do not have the right conditions for intelligent, signal sending beings to evolve. The terrible irony is that when intelligent life does develop against these odds - taking billions of years to do so - this privileged intelligent life also develops a disturbing propensity to self-destruct, whether by war, over-ambition, greed, resource depletion, home planet destruction or by a combination thereof.
'Evolutionary pressures in many environments favor species which rapidly consume available resources once they achieve dominance. By the time they have achieved sufficient technology to come to the notice of other civilizations, they are already well on their way to exhausting the resources of their host planet. Therefore the time period available for communication is finite, and very small compared with planetary timescales. Once a planet's finite resources are exhausted no further species on that planet can develop advanced technology.'
And so here we are, several decades since we developed the technology to send signals into space. We stand at a crossroads, at the final stage of the Drake Equation, where the length of time we can release detectable signals into space is being decided. Are we a civilisation which will overcome its short-sightedness and aggressively address the threats we have created or will the majority continue along its current path of mindless consumption, continuing to destroy the planet - taking with them those who are prepared to change - just as we begin to discover an unparalleled level of technological prowess?
It is imperative for us to overhaul our outdated paradigms, in particular toward consumption if we are to survive into the next stage of human evolution. We stand upon the threshold of groundbreaking advancements into interstellar travel, longevity, the abolition of disease, and of moving closer to a deep understanding of the elusive nature of reality and time. We could have all this, so long as we are responsible stewards of the planet which gives us life. Without her, we die - no matter how clever we otherwise become.
The warning is there, theoretically for now, since we have not heard anything but that one signal in 1977, which incidentally bore the hallmarks of an interstellar signature that ran for seventy-two seconds and then stopped never to be found again. Perhaps that signal came from another civilisation, a message we were unable to understand, and wrote off as an anomaly. If it was a message, I wonder what they were saying to the vast reaches of empty space.
