Hyperspace (47 page)

The two most promising planets, Venus and Mars, have turned up no signs of life, let alone advanced civilizations. Venus, named after the goddess of love, was once envisioned by astronomers as well as romantics to be a lush, tropical planet. Instead, our space probes have found a harsh, barren planet, with a suffocating atmosphere of carbon dioxide, blistering temperatures exceeding 800°F, and toxic rains of sulfuric acid.

Mars, the focus of speculation even before Orson Welles caused panic in the country in 1938 during the Depression with his fictional broadcast about an invasion from that planet, has been equally disappointing. We know it to be a desolate, desert planet without traces of surface water. Ancient riverbeds and long-vanished oceans have left their distinctive mark on the surface of Mars, but we see no ruins or any indications of civilization.

Going beyond our solar system, scientists have analyzed the radio emissions from nearby stars with equally fruitless results. Dyson has stressed that any advanced civilization, by the Second Law of Thermodynamics, must necessarily generate large quantities of waste heat. Its energy consumption should be enormous, and a small fraction of that waste heat should be easily detected by our instruments. Thus, Dyson claims, by scanning the nearby stars, our instruments should be able find the telltale fingerprint of waste heat being generated by an advanced civilization. But no matter where we scan the heavens, we see no traces of waste heat or radio communications from Type I, II, or III civilizations. On our own earth, for example, we have mastered the art of radio and television within the past half-century. Thus an expanding sphere of radio waves, about 50 light-years in radius, surrounds our planet. Any star within 50 light-years of earth, if it contains intelligent life, should be able to detect our presence. Likewise, any Type II or III civilization should be broadcasting copious quantities of electromagnetic radiation continuously for the past several thousand years, so that any intelligent life within several thousand light-years of the civilization’s planet should be able to detect its presence.

In 1978, astronomer Paul Horowitz scanned all sunlike star systems
(185 in all) within 80 light-years of our solar system, and found no traces of radio emissions from intelligent life. Astronomers Donald Goldsmith and Tobius Owen reported in 1979 a search of more than 600 star systems, also with negative results. This search, called SETI (search for extraterrestrial intelligence), has met with consistent failure. (Encouragingly, in a rare display of scientific generosity, in 1992 Congress appropriated $100 million to be spent over a 10-year period for the High Resolution Microwave Survey, which will scan the nearby stars for intelligent life. These funds will make it possible for the gigantic 305-meter fixed radio dish at Arecibo, Puerto Rico, to scan select stars systematically within 100 light-years of the earth. This will be complemented by the 34-meter movable radio antenna at Goldstone, California, which will sweep broad portions of the night sky. After years of negative results, astronomer Frank Drake of the University of California at Santa Cruz is cautiously optimistic that they will find some positive signs of intelligent life. He remarks, “Many human societies developed science independently through a combination of curiosity and trying to create a better life, and I think those same motivations would exist in other creatures.”)

The puzzle deepens when we realize that the probability of intelligent life emerging within our galaxy is surprisingly large. Drake even derived a simple equation to calculate the number of planets with intelligent life forms in the galaxy.

Our galaxy, for example, contains about 200 billion stars. To get a ballpark figure for the number of stars with intelligent life forms, we can make the following very crude estimate. We can be conservative and say that 10% of these stars are yellow stars much like the sun, that 10% of those have planets orbiting them, that 10% of those have earthlike planets, that 10% of those have earthlike planets with atmospheres compatible with life, that 10% have earthlike atmospheres with life forms growing in them, and that 10% of those have some form of intelligent life. This means that one-millionth of the 200 billion stars in the galaxy will probably have some intelligent life form. This implies that a staggering 200,000 stars will have planets harboring some form of intelligent life. A slightly more optimistic set of values for Drake’s equation shows that intelligent life might be, on the average, as close as 15 light-years from our sun.

With recent advanced computer techniques, scientists have been able to refine Drake’s original back-of-the-envelope calculation. George W. Wetherill of the Carnegie Institution of Washington, for example, has run computer simulations of the early evolution of our solar system, beginning with a large, swirling disk of gas and dust around the sun. He
lets the computer evolve the disk until small, rocky masses begin to coalesce out of the dust. Much to his pleasant surprise, he found that planets of approximately the size of the earth were easy to evolve out of these rocky cores. Most of the time, in fact, earth-size planets spontaneously coalesced with masses between 80% and 130% of the earth’s distance from the sun. (Curiously, he also found that the formation of Jupiter-size planets far from the sun was important for the evolution of the earth-size planets. The Jupiter-size planets were essential to sweep out swarms of comets and debris that would eventually strike the earthlike planet, extinguishing any primitive life forms on it. Wetherill’s computer simulations show that without a Jupiter-like planet to clean out these comets with its gigantic gravitational pull, these comets would hit the earthlike planet about 1,000 times more frequently than they do in reality, making a life-destroying impact every 100,000 years or so.)

Thus it is a compelling (but certainly not rigorous) conclusion that the laws of probability favor the presence of other intelligence within the galaxy. The fact that our galaxy is perhaps 10 billion years old means that there has been ample time for scores of intelligent life forms to have flourished within it. Type II and III civilizations, broadcasting for several hundred to several thousand years, should be sending out an easily detectable sphere of electromagnetic radiation measuring several hundred to several thousand light-years in diameter. Yet we see no signs of intelligent life forms in the heavens.

Why?

Several speculative theories have been advanced to explain why we have been unable to detect signs of intelligent life out to 100 light-years of our planet. None of them is particularly satisfying, and the final truth may be a combination of all of them.

One theory holds that Drake’s equation may give us rough probabilities of how many planets contain intelligent life, but tells us nothing about when these planets attain this level of development. Given the astronomical time scales involved, perhaps Drake’s equation predicts intelligent life forms that existed millions of years before us, or will exist millions of years after us.

For example, our solar system is approximately 4.5 billion years old. Life started on the earth about 3 to 4 billion years ago, but only within the past million years has intelligent life developed on the planet (and only within the past few decades has this civilization built radio stations capable of sending signals into outer space). However, 1 million years, on the time scale of billions of years, is but an instant of time. It is reasonable to assume that thousands of advanced civilizations existed
before our distant ancestors even left the forest and have since perished, or that thousands more civilizations will develop long after ours has died. Either way, we would not be able to detect them via our instruments.

The second theory holds that the galaxy is, in fact, teeming with advanced forms of civilizations, but they are advanced enough to conceal their existence from our prying instruments. We would mean nothing to them because they are so many millions of years ahead of us. For example, if we stumble on an ant colony while walking in a field, our first impulse is certainly not to make contact with the ants, ask to see their leader, wave trinkets before their eyes, and offer them unparalleled prosperity and the fruits of our advanced technology. More likely, our first temptation is to ignore them (or perhaps even step on a few of them).

Puzzled by these long-standing questions, I asked Dyson if he thought we would soon be making contact with extraterrestrial life forms. His answer rather surprised me. He said, “I hope not.” I thought it was strange that someone who had spent decades speculating about intelligent civilizations in outer space should have reservations about actually meeting them. Knowing British history, however, he must have had good reasons for not rushing in to embrace other civilizations. British civilization was probably only several hundred years more advanced than many of the civilizations, such as the Indian and the African, conquered by the British army and navy.

Although most science-fiction writers bewail the limitations on space exploration placed by the speed of light, Dyson takes the unorthodox view that perhaps this is a good thing. Viewing the often bloody history of colonialism throughout our own world history, perhaps it is a blessing in disguise, he muses, that various Type II civilizations will be separated by large distances and that the Planck energy is inaccessible. Looking at the bright side, he quipped, “At least, one can evade the tax collector.”

Unfortunately, the meeting of two unequal civilizations has often had catastrophic implications for the weaker one. For example, the Aztec civilization had risen over thousands of years to great prominence in central Mexico. In some areas, its mastery of science, art, and technology rivaled the achievements of Europe. However, in the area of gunpowder and warships, the Aztecs were perhaps several centuries behind the Spanish. The sudden clash between a small, ragged band of 400 conquistadors and the advanced civilizations of the Aztecs ended in tragedy in 1521. Within a brief period of time, the Aztec people, with a population numbering in the millions, were systematically crushed and enslaved to work in the mines. Their treasuries were looted, their history
was erased, and even the faintest memory of the great Aztec civilization was obliterated by waves of missionaries.

When we think of how we might react to visitors from outer space, it is sobering to read how the Aztecs reacted to the visitors from Spain: “They seized upon the gold as if they were monkeys, their faces gleaming. For clearly their thirst for gold was insatiable; they starved for it; they lusted for it; they wanted to stuff themselves with it as if they were pigs. So they went about fingering, taking up the streamers of gold, moving them back and forth, grabbing them to themselves, babbling, talking gibberish among themselves.”
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On a cosmic scale, the sudden interactions between civilizations could be even more dramatic. Because we are talking about astronomical time scales, it is likely that a civilization that is a million years ahead of us will find us totally uninteresting. Furthermore, there is probably little that our planet can offer these aliens in terms of natural resources that isn’t simultaneously available in numerous other star systems.

In the “Star Trek” series, however, the Federation of Planets encounters other hostile civilizations, the Klingons and Romulans, which are
precisely
at the same stage of technological development as the Federation. This may increase the drama and tension of the series, but the odds of this happening are truly astronomical. More likely, as we venture off into the galaxy in starships, we will encounter civilizations at vastly different levels of technological development, some perhaps millions of years ahead of us.

In addition to the possibilities that we may have missed other civilizations by millions of years and that other civilizations may not consider us worthy of notice, a third theory, which is more interesting, holds that thousands of intelligent life forms did arise from the swamp, but they were unable to negotiate a series of catastrophes, both natural and self-inflicted.
If this theory is correct, then perhaps someday our starships will find the ruins of ancient civilizations on far-off planets, or, more likely, our own civilization will be faced with these catastrophes. Instead of becoming “lords of the universe,” we may follow the road to self-destruction. Thus the question we ask is: What is the fate of advanced civilizations? Will we (they) survive long enough to master the physics of the tenth dimension?

The rise of civilizations is not marked by a steady and sure growth in technology and knowledge. History shows us that civilizations rise, mature, and then disappear, sometimes without a trace. In the future, perhaps humanity will unleash a Pandora’s box of technological horrors that threaten our very existence, from atomic bombs to carbon dioxide. Far from trumpeting the coming of the Age of Aquarius, some futurologists predict that we may be facing technological and ecological collapse. For the future, they conjure up the frightening image of humanity reduced to a pathetic, terrified Scrooge in Charles Dickens’s fable, groveling on the ground of his own grave and pleading for a second chance.

Unfortunately, the bulk of humanity is largely uncaring, or unaware, of the potential disasters facing us. Some scientists have argued that perhaps humanity, considered as a single entity, can be compared to a teenager careening out of control. For example, psychologists tell us that teenagers act as if they are invulnerable. Their driving, drinking, and drug habits are graphic proof, they say, of the devil-may-care recklessness that pervades their life-style and outlook. The main cause of death among teenagers in this country is no longer disease, but accidents, probably caused by the fact that they think they will live forever.

If that is true, then we are abusing technology and the environment as if we will live forever, unaware of the catastrophes that lie in the future. Society as a whole may have a “Peter Pan complex,” never wanting to grow up and face the consequences of its own irresponsibility.