Cosmic Connection (28 page)

I
n almost all scientific descriptions of contact between Earth and an extraterrestrial civilization, the extraterrestrial civilization is described as advanced.

Why advanced? Why aren’t there any primitive civilizations out there, backward fellows poking around, fumbling over interstellar debris, constantly botching things up? Why are we obsessed with advanced civilizations?

The answer is very simple: The primitive ones don’t talk to us. (The really smart ones may not talk to us, either, but that is a point I’ll come to in a moment.)
Let us consider contact using radio astronomy. Radio astronomy on Earth is a by-product of the Second World War, when there were strong military pressures for the development of radar. Serious radio astronomy emerged only in the 1950s, major radio telescopes only in the 1960s. If we define an advanced civilization as one able to engage in long-distance radio communication using large radio telescopes, there has been an advanced civilization on our planet for only about ten years. Therefore, any civilization ten years less advanced than we cannot talk to us at all.

Even rather optimistic estimates of the rate at which advanced technical civilizations emerge in the Galaxy are lower than one every ten years (see Chapter 28). If this is correct, it means that of all the civilizations in the Galaxy able to communicate by radio, there is none as dumb as we. There may be millions of civilizations less advanced than we, but we have no way to make contact with them: They lack the technology to receive or transmit. Objections that the
Pioneer 10
message may be too difficult for the recipients to decipher ignores the fact that the recipients must be able to acquire this tiny bit of space debris in interstellar space–a task vastly beyond our present capabilities. If they are advanced enough to capture
Pioneer 10
in the dark between the stars, they will, I think, be smart enough to make out its message, which can be read without special hinting by many physicists on as backward a planet as Earth (although, to be sure, those physicists share some genetic and cultural biases and chauvinisms with the authors of the message).

But what about civilizations vastly in advance of our own? The amount of technical progress we have made in the past few hundred years is startling. Not only have entire new technologies developed, but entire new laws of physics and entire new ways of examining the universe have evolved. This intellectual and technological development is continuing. If Earth’s civilization survives, the advance of science and technology will also continue.

Civilizations hundreds or thousands or millions of years beyond us should have sciences and technologies so far beyond our present capabilities as to be indistinguishable from magic. It is not that what they can do violates the laws of physics; it is that we will not understand how they are able to use the laws of physics to do what they do.

It is possible that we are so backward and so uninteresting to such civilizations as not to be worthy of contact, or at least of much contact. There may be a few specialists in primitive planetary societies who receive master’s or doctor’s degrees in studying Earth or listening to our raspy radio and television traffic. There may be amateurs–Boy Scouts, radio hams, and the equivalent–who may be interested in developments on Earth. But a civilization a million years in our future is unlikely, I believe, to be very interested in us. There are all those other civilizations a million years in our future for them to talk to.

Communications between two very advanced civilizations will likely use a science and a technology inaccessible to us. We therefore have no prospect for tuning in on such communications traffic, either accidentally or on purpose.

We are like the inhabitants of an isolated valley in New Guinea who communicate with societies in neighboring valleys (quite different societies, I might add) by runner and by drum. When asked how a very advanced society will communicate, they might guess by an extremely rapid runner or by an improbably large drum. They might not guess a technology beyond their ken. And yet, all the while, a vast international cable and radio traffic passes over them, around them, and through them.

At this very moment the messages from another civilization may be wafting across space, driven by unimaginably advanced devices, there for us to detect them–if only we knew how. Perhaps the message will come via radio waves to be detected by large radio telescopes. Or perhaps by more arcane devices, the modulation of X-ray stars, gravity waves, neutrinos, tachyons, or transmission channels that no one on Earth will dream of for centuries. Or perhaps the messages are already here, present in some everyday experience that we have not made the right mental effort to recognize. The power of such an advanced civilization is very great. Their messages may lie in quite familiar circumstances.

Consider, for example, seashells. Everyone knows the “sound of the sea” to be heard when putting a seashell to one’s ear. It is really the greatly amplified sound of our own blood rushing, we are told. But is this really true? Has this been studied? Has anyone attempted to decode the message being sounded by the seashell? I do not intend this example as literally true, but rather as an allegory. Somewhere on Earth there may be the equivalent of the seashell communications channel. The message from the stars may be here already. But where?

We will listen for the interstellar drums, but we will miss the interstellar cables. We are likely to receive our first messages from the drummers of the neighboring galactic valleys–from civilizations only somewhat in our future. The civilizations vastly more advanced than we will be, for a long time, remote both in distance and accessibility. At a future time of vigorous interstellar radio traffic, the very advanced civilizations may be, for us, still insubstantial legends.

F
or three generations of human beings there was–as an ever-present, but almost unperceived, part of their lives–a sound that beckoned, a call that pierced the night, carrying the news that there was a way, not so very difficult, to leave Twin Forks, North Dakota, or Apalachicola, Florida, or Brooklyn, New York. It was the wail of the night freight, as haunting and evocative as the cry of the loon. It was a constant reminder that there were vehicles, devices, which, if boarded, could propel you at high velocity out of your little world into a vaster universe of forests and deserts, seacoasts and cities.

Especially in the United States, but perhaps over much of the world, few people today travel by train. There are whole generations growing up which have never heard that siren call. This is the moment of the homogenization of the world, when the diversities of societies are eroding, when a global civilization is emerging. There are no exotic places left on Earth to dream about.

And for this reason there remains an even greater and more poignant need today for a vehicle, a device, to get us somewhere else. Not all of us; only a few–to the deserts of the Moon, the ancient seacoasts of Mars, the forests of the sky. There is something comforting in the idea that one day a few representatives of our little terrestrial village might venture to the great galactic cities.

There are as yet no interstellar trains, no machines to get us to the stars. But one day they may be here. We will have constructed them or we will have attracted them.

And then there will once again be the whistle of the night freight. Not the antique sort of whistle, for sound does not carry in interplanetary space or in the emptiness between the stars. But there will be something, perhaps the flash from magnetobrehmstrahlung, as the starship approaches the velocity of light. There will be a sign.

Looking out on a clear night from the continent-sized cities and vast game preserves that may be our future on this planet, youngsters will dream that when they are grown, if they are very lucky, they will catch the night freight to the stars.

I
n a by now much quoted and possibly even apocryphal story, the nuclear physicist Enrico Fermi asked, during a luncheon conversation at Los Alamos in the middle 1940s, “Where are they?” If there are vast numbers of beings more advanced then we, he was musing, why have we seen no sign of them–by a visitation to Earth, for example?

We have discussed this problem in Chapters 27 and 28. But there is another formulation of Fermi’s question. A civilization a hundred years in our technological future (assuming present rates of technological growth) would surely be able to communicate by radio, and possibly by other techniques, anywhere in the Galaxy and probably with other galaxies as well. A civilization thousands of years in our technological future will very likely be able to travel physically between the stars, although with the expenditure of considerable time and resources.

But what of civilizations tens of thousands or hundreds of thousands of years in our future, or even farther advanced? There are, after all, stars
billions
of years older than the Sun. The very oldest such stars lack heavy metals; probably their planets are similarly lacking. Such very old stars are inhospitable environments for the development of technological civilizations. But some stars one or two billion years older than the Sun have no such attendant difficulties. It is surely possible that there are at least a few civilizations hundreds of millions or billions of years in our technological future.

With prodigious energy resources, such civilizations should be able to rework the cosmos. We have discussed in Chapter 22 how life on Earth has already altered our planet significantly and how we can envision in the relatively near future making important changes in the environments of the nearby planets.

More major changes are possible in the somewhat more distant future. The mathematician Freeman Dyson, of the Institute for Advanced Study, offers a scheme in which the planet Jupiter is broken down piece by piece, transported to the distance of the Earth from the Sun, and reconstructed into a spherical shell–a swarm of individual fragments revolving about the Sun. The advantage of Dyson’s proposal is that all of the sunlight now wasted by not falling upon an inhabited planet could then be gainfully employed; and a population greatly in excess of that which now inhabits the Earth could be maintained. Whether such a vast population is desirable is an important and unsolved question. But what seems clear is that at the present rate of technological progress it will be possible to construct such a Dyson sphere in perhaps some thousands of years. In that case, other civilizations older than we may have already constructed such spherical swarms.

A Dyson sphere absorbs visible light from the Sun. But it does not continue indefinitely to absorb this light without re-radiating; otherwise, the temperature would become impossibly high. The exterior of the Dyson sphere radiates infrared radiation into space. Because of the large dimensions of the sphere, the infrared flux from a Dyson sphere should be detectable over quite sizable distances–with present infrared technology, over distances of hundreds to thousands of light-years. Remarkably enough, large infrared objects of roughly Solar System dimensions and of temperatures less than 1,000 degrees Fahrenheit have been detected in recent years. These, of course, are not necessarily Dyson civilizations. They may be vast dust clouds surrounding stars in the process of formation. But we are beginning to detect objects that are not dissimilar to the artifacts of advanced civilizations.