As the search for extraterrestrial intelligence (SETI) enters a new phase, with the recent start of observations for radio signals from other worlds with the SETI Institute's Allen Telescope Array, the international scientific community has begun preparing all the more earnestly for the cascade of events that would follow the detection of an alien civilization. Among the most important questions humankind will ponder on that day is whether we should reply, and if so, what we should say.

If such a signal from the stars bears a readily intelligible message, some of our choices may be laid out for us. Perhaps, some have argued, a message from extraterrestrials will include their suggestions for a reply. After all, the reasoning goes, they will probably have made contact with many other civilizations before us, so they will be well versed in the productive first steps in interspecies communication.

Personally, I am skeptical that we will be able to decode a message from another world with ease. But whether we know what they are saying, or whether we only have evidence that intelligence exists beyond Earth, if we choose to reply, we will need to decide what we should say about ourselves.

Older neighbors

But what could we say that would be of interest to extraterrestrials?

Before we answer that question, we must acknowledge that any extraterrestrials we make contact with may well be thousands or millions of years more advanced than we are. Why do SETI scientists assume this? Because for our search to succeed, it needs to be true.

If the galaxy is populated only by young civilizations that have the capacity for interstellar communication for only a few decades before they destroy themselves or simply lose interest in making contact with other worlds, then we will effectively be isolated, alone in the universe. If other civilizations transmit evidence of their existence for only a few decades ? the length of time that humans have been capable of interstellar communication ? and then they lose the interest or ability to make contact, it's extremely unlikely that the precise time they are transmitting and the time that we are listening will coincide. On a galactic scale, where time is measured in billions of years, it is extremely unlikely that these two "blips" would happen at the same time. This would be as unlikely as two fireflies each lighting up once, at exactly the same time, during the course of a long, dark night. The chance that both would flash on simultaneously is virtually zero; it's more likely their flashes would be separated by minutes or hours. So too is it unlikely that two short-lived civilizations that had evolved independently of one another would come into being at almost precisely the same time in the fourteen billion year history of our galaxy.

If we hear from a distant civilization, on purely statistical grounds it's very likely they will be our elders.

Images of light and darkness

The most detailed messages thus far sent to another civilization were the recordings borne by two Voyager spacecraft, which will continue to drift between the stars for millions of years after having completed their primary mission of planetary exploration within our solar system.

Perhaps the most striking commonality of the more than a hundred pictures and drawings on the Voyager recordings is that their depictions of humankind are universally positive. The photographs abound with images of family and cooperation. But nowhere in these images do we see direct evidence of humanity's darker side. Absent are any images of poverty or war, of environmental degradation or genocide.

Presenting the positive side of life on Earth in the Voyager recordings was a natural attempt to put our best foot forward. But, I would argue, perhaps the most important contribution we could make in an interstellar conversation would be to acknowledge those parts of ourselves that we are least proud of.

If another civilization is much older than we are, it will have made its way through the bottleneck of technological adolescence, where a civilization's self-destructive capacity outweighs its social maturity. We may be in a poor position to advise another civilization about how to be more wise. But we are quite well-suited to provide a reminder of what life is like for a civilization that does not have the confidence that it will continue to exist into the coming centuries and millennia. Our greatest contribution to an interstellar dialogue may come, not by emphasizing our accomplishments and virtues, but by recognizing our foibles and frailties. And in the process, we may learn important lessons about ourselves.

Acknowledging our shadow

The psychoanalyst Carl Gustav Jung believed that maturity depends on an ability to connect with our "shadow" side: those aspects of ourselves we normally try to hide from. "Unfortunately, there can be no doubt that man is, on the whole, less good than he imagines himself or wants to be," Jung wrote. And the consequences of not facing our shadow side are ominous. "Everyone carries a shadow," Jung continued, "and the less it is embodied in the individual's conscious life, the blacker and darker it is. If an inferiority is conscious, one always has a chance to correct it .... But if it is repressed and isolated from consciousness, it never gets corrected."

We might well imagine a more comprehensive message than the Voyager recordings that gave additional details about our cultures but failed to highlight the current threats to our environment, the costs of war, or the strife between nations and ethnicities. But might not such an attempt to put the best face on our current situation unintentionally reveal a potentially far more dangerous fault of humankind: a tendency to hide from our own problems and to avoid these threats to our very existence?

Some have suggested that the greatest value of contacting other civilizations may be a chance to glimpse into our future. If we learn that other civilizations have been able to survive through their technological adolescence, we would have new reason to hope that our own civilization will survive as well.

But even if we never make contact with another world, the process of preparing for contact may help us become better, more integrated humans. By reflecting on how we would portray ourselves to other worlds, we also have an opportunity to grow in our own self-understanding. And part of that increased self-understanding can come about through a recognition of those aspects of ourselves that we would rather not be true, but that are a part of ourselves.

In a sense, the composition of messages to other worlds becomes a process not merely of being in touch with alien worlds beyond, but of unknown worlds within. And such an exploration into our souls requires as much fortitude as does building and sustaining telescopes that will search the stars for decades and centuries, seeking evidence of life beyond Earth. As we look within, let's not forget to look at those parts of ourselves that we would rather look away from. As Jung reminded us, "no one can become conscious of the shadow without considerable moral effort. To become conscious of it involves recognizing the dark aspects of the personality as present and real. This act is the essential condition for any kind of self-knowledge."

Douglas Vakoch is the Director of Interstellar Message Composition at the SETI Institute and Chair of the Faculty at the California Institute of Integral Studies.

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