Sagan, SETI, statistics and the Drake Equation

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“From this distant vantage point, the Earth might not seem of particular interest. But for us, it’s different. Consider again that dot. That’s here, that’s home, that’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves. The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand. It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known” — Carl Sagan (reflecting on the Pale Blue Dot photograph of the Earth taken by the Voyager 1 spacecraft on July 6, 1990)

Image Credit: NASA Goddard Space Flight Center, Voyager 1

Carl Sagan was a childhood hero of mine. The calm voice of logic explaining frontier physics and philosophy in the simplest of terms that shone through the adolescent haze. But, despite his careful description of the Drake Equation for the number of possible communicating civilisations in our galaxy put forward in 1961 by Frank Drake, the Fermi paradox has itched at my mind ever since.

Image Credit: Michael Taylor

Why is it that given what seem reasonably high estimates for the probability of the existence of extraterrestrial civilizations, there is a lack of evidence for, or contact with, such civilizations? Remember Olber’s paradox? The paradox states that at any angle from the Earth the line of sight will end at the surface of a star – so why is the night sky dark? It’s like standing in a forest full of white trees. If at any every line of sight ends on the surface of a tree, shouldn’t you only see white? If, like us, similarly advanced technological civilisations, have launched space probes then surely, shouldn’t there be a space probe paradox too? In fact, should we not be bombarded by them? This points us back to the Drake Equation and our estimates of its parameters. A good starting point would appear to involve suitable measures of central tendency and dispersion for each parameter. Indeed, we have to also ask about hidden variables – those unidentified parameters that may also need inclusion. After all, it is a multivariate problem. Whatever your take on the issue, the Drake Equation, provides a useful starting point and the various new initiatives and ideas like the Rio scale that have sprung out of the now-ceased NASA Search for Extra-Terrestrial Intelligence (SETI) program by concerned individuals, should be remembered and celebrated as our first embryonic steps as a society communicating our will to communicate. We did it in the 70s and we can do it again. On the 16th of November 1974, we beamed a digitised radio message into space from the Arecibo radio telescope. Voyager I, launched on the 5th of September 1977, and drifting gently at a speed of about 3.6 Sun-Earth distances per year through the heliopause border of our Solar System carries the famous Golden Record.

Image Credits: Voyager Golden Record (NASA) & Pioneer 10 Plaque (NASA)

Last but not least is Pioneer 10, launched on the 3rd of March 1972 and bearing the sexy plaque on its bow, was the first artificial object to pass through the asteroid belt. Should we evolve upwards from our  0.72 value on the Kardashev scale toward a Type I civilisation, we should treat these initial efforts of our contemporaries with great respect and re-shape and re-think all of the paradoxes and equations with a cool head.

Image Credit: Wikipedia (Bennett Standeven)

As Voyager I continues boldly-on and humbly reminds us through its digital images that we are just a pixel on the spacetime landscape, we owe it our admiration and the Earth our respect.

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