Humans live and die by approximations. We are seldom as perfect or as accurate as we would like to be. And as we contemplate what we might say to an advanced extraterrestrial civilization, maybe that's a point we should emphasize.

If SETI succeeds, then it's very likely the civilization we discover will be much older than our own. The reasoning is simple. The only way we are likely to detect ET is if alien civilizations are much older than we are. If the typical civilization has the capacity to communicate by radio for only a few decades before it self-destructs, then it's very unlikely that we and they will happen to co-exist in the long lifetime of our galaxy. That disparity of age explains why current SETI programs merely listen for signals from other civilizations, rather than transmit. Transmitting requires greater patience and more resources than listening, so shouldn't we expect our cosmic elders to shoulder the burden?

Besides, what could a young civilization possibly have to offer in an intellectual exchange across interstellar space? Surely advanced aliens would have little to gain from our understanding of astronomy or physics, chemistry or mathematics. What then might we say to hold up our end of an interstellar conversation?

First Impressions

One of our natural tendencies, when we make contact with strangers, is to try to impress them. Otherwise sloppy dressers might polish their shoes for a job interview, hopeful suitors will wash their cars for a first date, and prospective children-in-law will be on their best behavior in the presence of the parents of their intended. And sometimes such careful self-presentation works — as my wife will readily attest.

Wouldn't we want to do the same in our first contact with ET? Lewis Thomas, in his book Lives of a Cell, suggests that if we want to impress an alien civilization, we should send "Bach, all of Bach, streamed out into space, over and over again." Thomas defends his choice by noting that "it is surely excusable for us to put the best possible face on at the beginning of such an acquaintance." And in fact when musical selections were chosen for the interstellar recording borne by two of the Voyager spacecraft, three of the 27 pieces were by Bach.

But perhaps even more impressive to an advanced civilization would be a more balanced presentation that reflects honestly on our foibles and shows a certain self-awareness of our imperfections. When looked at in this light, perhaps even a description of our somewhat primitive science, mathematics and technology could be illuminating to extraterrestrials.

For example, at a workshop on The Art and Science of Interstellar Message Composition sponsored by the SETI Institute and the Leonardo Network, artist Richard Clar emphasized the ways that the process of constructing messages could be instructive to ET. According to Clar, we might use technologies developed for other purposes to compose interstellar messages. For instance, if we wish to tell ET about the three-dimensional structure of the human body, we might create messages using medical imaging technologies like Computerized Axial Tomography — more commonly known as CAT-scans. The messages would also, indirectly, contain information about the level of our development as a species. Though our technologies may be crude by extraterrestrial standards, the rudimentary level of our accomplishments may itself be of interest to an advanced civilization, which might long since have forgotten the details of its own struggle to develop a stable, enduring society.

A Measured Response

Indeed, even a brief review of the history of terrestrial mathematics might prove of interest to an alien. As all high school geometry students can tell you, if we know the radius of a circle, we can easily calculate its circumference. Presumably, extraterrestrials would also know that c = 2pr, where "c" is the circumference of the circle and "r" is its radius.

What might surprise ET is how well humans get by, even when we are a bit inaccurate. Though we now know that the value of p is 3.14159 ? (and on it goes into infinity), earlier mathematicians used much cruder estimates of p. For example, when wise King Solomon was planning a bathing area in the great temple he was constructing, its specifications indicated that the pool would have a radius of 5 units and a circumference of 30 units. If you plug these numbers into the equation for calculating the circumference of a circle, you'll see that the value of p was estimated to be 3. While this number underestimates p by about 5%, by all accounts, the temple turned out to be quite spectacular. Perhaps the most important message that ET could gain from this example is that in spite of our imperfections and miscalculations, we humans are capable of moving forward, sometimes with a fair amount of style.

Embracing Imperfection

Indeed, rather than continually focusing on ways that we as a species are superior beings, perhaps as we attempt to make contact with ET, we should take the opposite approach. As a species we are, to put it bluntly, quite imperfect. More often than our egos would like to admit, we snap at our spouses, forget appointments, pay our bills late and round off important mathematical constants to the nearest integer.

Perhaps somewhere out there, circling a distant star, is an extraterrestrial civilization a million years our senior. Having long ago conquered war, poverty, and disease, having formed a stable society capable of enduring on timescales that stagger our imaginations, what would they think of our human flaws and imperfections? If some day we send them a message of our own, signaling our interest in joining the Galactic Club, would our application simply be laughed off?

Who knows? They might be surprised, perhaps even pleasantly so, to discover a young civilization that would initiate a conversation in which each exchange could take hundreds or thousands of years. Wise old extraterrestrials might even admire our audacity for believing that, in spite of our shortcomings, humans may continue to exist in the coming centuries — perhaps even long enough to receive a reply from ET.

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  • Scenes from SETI@Arecibo
  • Image Gallery: Voyager's Photo Legacy