Coming of Age in the Milky Way (57 page)

The network, once established, could be endowed with a number of salutary features. For one thing, it could be assigned the task of acquiring signals from new worlds and bringing them on-line. Indeed, its stations might broadcast acquisition signals for the purpose of attracting the attention of such relatively undeveloped planets. If so, the first signal intercepted by a SETI radiotelescope might come from an automated station sited far from any inhabited planet. In order to accomplish this and other tasks efficiently, the network should be made capable not only of repairing itself but also of expanding as the growing body of data requires. Here the technology of the self-replicating probes comes in handy; the network could dispatch probes to strategically favorable star systems in the galaxy, where each would build itself into a new junction station that would in turn hook up with the rest of the network.

Most important, the network should be equipped with a commodious
and self-expanding memory, one that is replicated and regularly updated at every station. The great advantage of this is that it alleviates the Q and A problem. What one wants from interstellar communication is not really conversation, which takes too long, but
information:
One wants to know who else lives in the galaxy, what they look like and how they think and what they do, and about their history and that of the species that preceded them. To make this and all other information available to everyone interested, one should have the network
remember
everything that it conveys.

The network, then, would be not only a telephone or television system, but also a computer and a library, access to which would be as near as the nearest junction. If a species of intelligent birds on one side of the galaxy were interested in the biology of a species of intelligent reptiles on the opposite side of the galaxy, they would not have to send a direct message and wait two hundred thousand years for a reply. Instead, the information would already be stored in the memory banks of the network itself, and the requisite Q and A time would be little longer than the light travel time to and from the nearest network junction. Nor would the information be hostage to the fate of any particular world; once submitted to the network, it could survive indefinitely.

Direct radio communication between intelligent species would be relatively slow and inefficient. Here, eight inhabited worlds scattered around the galaxy are communicating directly. The average Q&A time is one hundred thousand years.

Networking of interstellar communication greatly improves the efficiency of the system. This rudimentary network, consisting of only four junctions, cuts the Q&A time (for communication with the terminals’ memory banks) in half, to fifty thousand years. By adding more junction stations to the network, the Q&A time can be reduced to a century or less.

We arrive, then, at the prospect of an immortal system, constantly expanding and continually acquiring and storing information from all the worlds that choose to subscribe to it. In the long run, the network itself might reasonably be expected to evolve into
the single most knowledgeable entity in the galaxy. It alone could survey the full sweep of galactic history and experience the development of knowledge on a panstellar scale. Growing in sophistication and complexity with the passage of aeons, forever articulating itself among the stars, the network would come to resemble nothing so much as the central nervous system of the Milky Way.

Which, perhaps, is the ultimate purpose of intelligence, if life and intelligence may be said to have a purpose. We often find that our deepest yearnings have less to do with ourselves than with the wider scheme of things. (Love, which makes the world go round, is a highly individual experience, but its ultimate function is to perpetuate and advance the species.) Perhaps this is true as well of our deep but seemingly inexplicable desire to learn whether we are alone in the galaxy. Life might be the galaxy’s way of evolving a brain.

The process could extend beyond the galaxy, too, through contact with similar networks in other galaxies. Intergalactic Q and A times go to many millions of years—too long a wait for mortal beings, even if they are as longevous as Joshua trees, but perfectly manageable for an interstellar network. The network could afford to fashion giant antennae, use them to broadcast powerful acquisition signals to the Andromeda galaxy, to Centaurus A, even to the populous heart of the Virgo Supercluster, sixty million light-years distant, and then wait for a reply. Every world on every network would stand to benefit as galaxy after galaxy established contact, spinning electromagnetic threads across the expanding universe and exchanging the wealth of galactic libraries. The human species is only about two million years old, a time equal to that required for a message to travel one-way from the Andromeda galaxy to ours; we cannot very well expect to start up a meaningful dialogue with a society in Andromeda. But if information about Andromeda and the history of its worlds were already stored in our galaxy’s network, we might be able to begin accessing it within a matter of decades after making contact.

All this may be a dream. Certainly it is no more than a conjecture, and a materialist’s conjecture at that; what could be more materialistic than a galactic “intelligence” composed of communicating computers that rear themselves up out of the ash-gray rocks of dead asteroids? Yet it points to an idealistic vision of worlds by
the thousands, some in their youth and some in their graves, linked by an intergalactic mechanism devoted to pure thought. And, it suggests a cosmic role for intelligence—that the combination of intelligence and technology could awaken the universe to its own life and thought and history. That would make us all the substance of a cosmic mind.

           
I
n this book I have discussed how we inhabitants of this one world pieced together a credible picture of the (much) larger universe. I have described this process as a “coming of age,” by which I mean that we have, through centuries of fitful effort, finally begun to comprehend a few of the fundamental facts about the universe an acquaintanceship with which presumably is prerequisite to the most modest claim of cosmological maturity. We now know, for example,
where
we are—that we live on a planet orbiting a star located out toward one edge of a spiral galaxy, which in turn lies near the outskirts of a supercluster of galaxies, whose position has been determined relative to several neighboring superclusters that altogether harbor some forty thousand galaxies arrayed across a million billion cubic light-years of space. We also know, more or less,
when
we have come upon the scene—at about five billion years since the sun and its planets formed, in an expanding universe that is probably between twice and four times that old. We have discerned the basic mechanisms responsible for the evolution of life on Earth, found evidence of chemical evolution on the cosmic scale as well, and learned enough physics to investigate nature on a wide range of scales, from the jitterbugging of the quarks to the waltz of the galaxies.

These are accomplishments in which humanity can with justice take pride. Since the ancient Greeks first set the Western world on the path of science, our mensuration of the past has deepened from a few thousand years to over ten billion years, while that of space has expanded from a low-roof sky not much higher than the real distance of the moon to the more than ten-billion-light-year radius of the observable universe. We have reason to hope that our age will be remembered (if there is anyone around to remember it) for its contributions to the supreme intellectual treasure of any society, its concept of the universe at large.

And yet the more we know about the universe, the more we come to see how little we know. When the cosmos was thought to be but a tidy garden, with the sky its ceiling and the earth its floor and its history coextensive with that of the human family tree, it
was still possible to imagine that we might one day comprehend it in both plan and detail. That illusion can no longer be sustained. We might eventually obtain some sort of bedrock understanding of cosmic structure, but we will never understand the universe in detail; it is just too big and varied for that. If we possessed an atlas of our galaxy that devoted but a single page to each star system in the Milky Way (so that the sun and all its planets were crammed on one page), that atlas would run to more than ten million volumes of ten thousand pages each. It would take a library the size of Harvard’s to house the atlas, and merely to flip through it, at the rate of a page per second, would require over ten thousand years. Add the details of planetary cartography, potential extraterrestrial biology, the subtleties of the scientific principles involved, and the historical dimensions of change, and it becomes clear that we are never going to learn more than a tiny fraction of the story of our galaxy alone—and there are a hundred billion more galaxies. As the physician Lewis Thomas writes, “The greatest of all the accomplishments of twentieth-century science has been the discovery of human ignorance.”
¹

Our ignorance, of course, has always been with us, and always will be. What is new is our awareness of it, our awakening to its fathomless dimensions, and it is
this
, more than anything else, that marks the coming of age of our species. Space may have a horizon and time a stop, but the adventure of learning is endless. As the philosopher of science Karl Popper writes:

It is widely though erroneously supposed that science has to do with explaining everything, and that unexplained phenomena therefore upset scientists by threatening the hegemony of their world view. The technician in the white lab coat in the low-budget movie slaps palm to forehead when confronted with something novel, gasping, “But … there’s no
explanation
for this!” Actually, of course, any worthy scientist will rush to embrace the
unexplained, for without it science would get nowhere. It is the grand, mystical systems of thought, couched in terminologies too vague to be wrong, that explain everything and seldom err and do not grow.