Contact

by Carl Sagan

Ellie began to visit the university’s modest radio telescope in nearby Harvard, Massachusetts, eventually getting an invitation to help with the observations and the data analysis. She was accepted as a paid summer assistant at the National Radio Astronomy Observatory in Green Bank, West Virginia, and upon arrival, gazed in some rapture at Grote Reber’s original radio telescope, constructed in his backyard in Wheaton, Illinois, in 1938, and now serving as a reminder of what a dedicated amateur can accomplish. Reber had been able to detect the radio emission from the center of the Galaxy when no one nearby happened to be starting up the car and the diathermy machine down the street was not in operation. The Galactic Center was much more powerful, but the diathermy machine was a lot closer.

They were trying to measure how the number of distant extragalactic radio sources increased as they looked deeper into space.

In due course, she graduated cum laude from Harvard and went on for graduate work in radio astronomy at the other end of the country, at the California Institute of Technology.

For a year, she apprenticed herself to David Drumlin.

Others looked on graduate students as resources for the future, as their intellectual torchbearers to the next generation. But Drumlin, she felt, had quite a different view. For him, graduate students were gunslingers. There was no telling which of them might at any moment challenge him for the reigning title of “Fastest Gun in the West.” They were to be kept in their places. He never made a pass at her, but sooner or later, she was certain, he was bound to try.

In her second year at Cal Tech, Peter Valerian returned to campus from his sabbatical year abroad.

There was one slightly disreputable aspect of his scientific career: He was fascinated by the possibility of extraterrestrial intelligence. Each faculty member, it seemed, was allowed one foible: Drumlin had hang gliding and Valerian had life on other worlds. Others had topless bars, or carnivorous plants, or something called transcendental meditation. Valerian had thought about extraterrestrial intelligence, abbreviated ETI, longer and harder—and in many cases more carefully—than anyone else.

Ellie loved to listen to him. It was like entering Wonderland or the Emerald City. Actually, it was better, because at the end of all his ruminations there was the thought that maybe this could really be true, could really happen. Someday, she mused, there might in fact and not just in fantasy be a message received by one of the great radio telescopes. But in a way it was worse, because Valerian, like Drumlin on other subjects, repeatedly stressed that speculation must be confronted with sober physical reality.

Valerian was sure they wouldn’t make it hard for us. They would try to make it easy, because if they wanted to communicate with dummies they would have to make allowances for the dummies. That’s why, he thought, he’d have a fighting chance if a message ever came. His lack of brilliance was in fact his strength. He knew, he was confident, what dummies knew.

As a topic for her doctoral thesis, Ellie chose, with the concurrence of the faculty, the development of an improvement in the sensitive receivers employed on radio telescopes. It made use of her talents in electronics, freed her from the mainly theoretical Drumlin, and permitted her to continue her discussions with Valerian—but without taking the professionally dangerous step of working with him on extraterrestrial intelligence.

She was working on the ruby maser. A ruby is made mainly of alumina, which is almost perfectly transparent. The red color derives from a small chromium impurity distributed through the alumina crystal. When a strong magnetic field is impressed on the ruby, the chromium atoms increase their energy or, as physicists like to say, are raised to an excited state. She loved the image of all the little chromium atoms called to feverish activity in each amplifier, frenzied in a good practical cause—amplifying a weak radio signal. The stronger the magnetic field, the more excited the chromium atoms became. Thus the maser could be tuned so that it was particularly sensitive to a selected radio frequency. She found a way to make rubies with lanthanide impurities in addition to the chromium atoms, so a maser could be tuned to a narrower frequency range and could detect a much weaker signal than previous masers. Her detector had to be immersed in liquid helium. She then installed her new instrument on one of Cal Tech’s radio telescopes in Owens Valley and detected, at entirely new frequencies, what astronomers call the three-degree black-body background radiation—the remnant in the radio spectrum of the immense explosion that began this universe, the Big Bang.

She would explain to nonscientist friends that she liked rubies but couldn’t afford them. It was a little like the scientist who first discovered the biochemical pathway of green plant photosynthesis, and who forever after wore pine needles or a sprig of parsley in his lapel. Colleagues, their respect for her growing, considered it a minor idiosyncrasy.

As civilian and military radio traffic has increased, radio telescopes have had to hide—sequestered in an obscure valley in Puerto Rico, say, or exiled to a vast scrub desert in New Mexico or Kazakhstan.

After receiving her doctorate, Ellie accepted an appointment as research associate at the Arecibo Observatory, a great bowl 305 meters across, fixed to the floor of a karst valley in the foothills of northwestern Puerto Rico.

Some astronomers lived near the Observatory, but the isolation, compounded by ignorance of Spanish and inexperience with any other culture, tended to drive them and their wives toward loneliness and anomie. Some had decided to live at Ramey Air Force Base, which boasted the only English-language school in the vicinity. But the ninety-minute drive also heightened their sense of isolation. Repeated threats by Puerto Rican separatists, convinced erroneously that the Observatory played some significant military function, increased the sense of subdued hysteria, of circumstances barely under control.

Many months later, Valerian came to visit. Nominally he was there to give a lecture, but she knew that part of his purpose was to check up on how she was doing and provide some semblance of psychological support. Her research had gone very well. She had discovered what seemed to be a new interstellar molecular cloud complex, and had obtained some very fine high time-resolution data on the pulsar at the center of the Crab Nebula. She had even completed the most sensitive search yet performed for signals from a few dozen nearby stars, but with no positive results.

From her scant supply in the community refrigerator, she had made a rudimentary picnic lunch, and Valerian sat with her along the very periphery of the bowl-shaped dish.

They exchanged bits of gossip and current scientific tidbits. The conversation turned to SETI, as the search for extraterrestrial intelligence was beginning to be called. “Have you ever thought about doing it full time, Ellie?” he asked. “I haven’t thought about it much. But it’s not really possible, is it? There’s no major facility devoted to SETI full-time anywhere in the world, as far as I know.” “No, but there might be. There’s a chance that dozens of additional dishes might be added to the Very Large Array, and make it into a dedicated SETI observatory. They’d do some of the usual kind of radio astronomy also, of course. It would be a superb interferometer. It’s only a possibility, it’s expensive, it needs real political will, and it’s years away at best. Just something to think about.”

“I know, I know. But don’t you have the sense that if they’re anywhere, they’re everywhere? If really advanced guys live a thousand light-years away, shouldn’t they have an outpost in our backyard? You could do the SETI thing forever, you know, and never convince yourself that you’d completed the search.”

CHAPTER 3

White Noise

The pulses had been journeying for years through the great dark between the stars.

The pulses were encountering a horde of giant snowballs.

Casually dressed in a knit T-shirt and khaki skirt, she strolled along a hallway on the first floor and entered a door marked “E. Arroway, Director.”

Turning on a desk lamp, she rummaged through a drawer, finally producing a pair of earphones.

Through the window she could see a few of the 131 radio telescopes that stretched for tens of kilometers across the New Mexico scrub desert like some strange species of mechanical flower straining toward the sky.

In the scant few decades in which humans have pursued radio astronomy, there has never been a real signal from the depths of space, something manufactured, something artificial, something contrived by an alien mind. There have been false alarms. The regular time variation of the radio emission from quasars and, especially, pulsars had at first been thought, tentatively, tremulously, to be a kind of announcement signal from someone else, or perhaps a radio navigation beacon for exotic ships that plied the spaces between the stars.

And there had been other rich and mysterious messages that had turned out to be intelligent after a fashion but not very extraterrestrial.

Project Argus was the largest facility in the world dedicated to the radio search for extraterrestrial intelligence.

Argus had been in full operation for more than four years. There had been glitches, bogeys, intimations, false alarms. But no message.

She sat down before one of the consoles and plugged in the earphones. It was futile, she knew, a conceit, to think that she, listening on one or two channels, would detect a pattern when the vast computer system monitoring a billion channels had not. But it gave her a modest illusion of utility.

At other times, like now, when the static was clearly patternless, she would remind herself of Shannon’s famous dictum in information theory, that the most efficiently coded message was indistinguishable from noise, unless you had the key to the encoding beforehand.

There were a billion channels to choose from. You could spend your life trying to outguess the computer, listening with pathetically limited human ears and brains, seeking a pattern.

“It’s Dr. Drumlin on the phone. He’s in Jack’s office and says he has an appointment with you.” “Holy smoke, I forgot.”

He had come to Argus to give the weekly scientific colloquium. But, she found, he had come for another purpose as well. He had written a letter to the National Science Foundation urging that Argus terminate its search for extraterrestrial intelligence and devote itself full-time to more conventional radio astronomy.

“But we’ve only been at it four and a half years. We’ve looked at less than a third of the northern sky. This is the first survey that can do the entire radio noise minimum at optimum bandpasses. Why would you want to stop now?”

“No, Ellie, this is endless. After a dozen years you’ll find no sign of anything. You’ll argue that another Argus facility has to be built at a cost of hundreds of millions of dollars in Australia or Argentina to observe the southern sky. And when that fails, you’ll talk about building some paraboloid with a free-flying feed in Earth orbit so you can get millimeter waves. You’ll always be able to think of some kind of observation that hasn’t been do...

“Oh, Dave, we’ve been through this a hundred times. If we fail, we learn something of the rarity of intelligent life—or at least intelligent life that thinks like we do and wants to communicate with backward civilizations like us. And if we succeed, we hi...

“There are first-rate projects that aren’t finding telescope time. There’s work on quasar evolution, binary pulsars, the chromospheres of nearby stars, even those crazy interstellar proteins. These projects are waiting in line because this facility—by far the b...

“Seventy-five percent for SETI, Dave, twenty-five percent for rout...

“Don’t call it routine. We’ve got the opportunity to look back to the time that the galaxies were being formed, or maybe even earlier than that. We can examine the cores of giant molecular clouds and the black holes at the centers of galaxies. There’s a revo...

“Dave, try not to personalize this. Argus would never have been built if there wasn’t public support for SETI. The idea for Argus isn’t mine. You know they picked me as director when the last forty dishes wer...

“Not entirely, and not if I have anything to say about it. This is grandstanding. This is pandering to UFO kooks and comic s...

Despite what seemed like a lifetime of effort on her part, there was still a host of male scientists who only talked to each other, insisted on interrupting her, and ignored, when they could, what she had to say. Occasionally there were those like Drumlin who showed a positive antipathy.

Drumlin’s impatience with Argus, she knew, was shared by many astronomers.

Astronomers at other institutions were making extraordinary discoveries among the stars and galaxies, picking out those objects which, by whatever mechanism, generated intense radio waves. Other radio astronomers published scientific papers, attended meetings, were uplifted by a sense of progress and purpose. The Argus astronomers tended not to publish and were usually ignored when the call went out for invited papers at the annual meeting of the American Astronomical Society or the triennial symposia and plenary sessions of the International Astronomical Union.

Could Dave be right? Could SETI and Argus be a kind of collective delusion of a few insufficiently hard-nosed astronomers? Was it true that no matter how many years went by without the receipt of a message, the project would continue, always inventing a new strategy for the transmitting civilization, continually devising novel and expensive instrumentation?

What would be a convincing sign of failure? When would she be willing to give up and turn to something safer, something more guaranteed of results?

If they wanted to communicate with us, they would make it easy for us. They would send signals at many different frequencies. They would use many different modulation timescales. They would know how backward we are, and would have pity.

So why had we received no signal?