by Ben Bova
“I completely agree,” I said. “But listening for radio signals is the wrong way to do it.”
“Huh?”
“Radio broadcasting requires too much power to cover interstellar distances efficiently. We should be looking for signals, not listening for them.”
“Looking?”
“Lasers,” I said, pointing to the low-key lights over the consoles. “Optical lasers. Superlamps shining out in the darkness of the void. Pump in a modest amount of electrical power, excite a few trillion atoms, and out comes a coherent, pencil-thin beam of light that can be seen for millions of miles.”
“Millions of miles aren’t light-years,” Rizzo muttered.
“We’re rapidly approaching the point where we’ll have lasers capable of lightyear ranges. I’m sure that some intelligent race somewhere in this galaxy has achieved the necessary technology to signal from star to star— by light beams.”
“Then how come we haven’t seen any?” Rizzo demanded. “Perhaps we already have.”
“What?”
“We’ve observed all sorts of variable stars—Cepheids, RR Lyrae’s, T Tauri’s. We assume that what we see are stars, pulsating and changing brightness for reasons that are natural, but unexplainable to us. Now, suppose what we are really viewing are laser beams, signalling from planets that circle stars too faint to be seen from Earth?”
In spite of himself, Rizzo looked intrigued.
“It would be fairly simple to examine the spectra of such light sources and determine whether they’re natural stars or artificial laser beams.”
“Have you tried it?”
I nodded.
“And?”
I hesitated long enough to make him hold his breath, waiting for my answer. “No soap. Every variable star I’ve examined is a real star.”
He let out his breath in a long, disgusted puff. “Ahhh, you were kidding all along. I thought so.”
“Yes,” I said. “I suppose I was.”
Time dragged along in the weather dome. I had managed to smuggle a small portable telescope along with me, and tried to make observations whenever possible. But the weather was usually too poor. Rizzo, almost in desperation for something to do, started to build an electronic image-amplifier for me.
Our one link with the rest of the world was our weekly radio message from McMurdo. The times for the messages were randomly scrambled, so that the chances of their being intercepted or jammed were lessened. And we were ordered to maintain strict radio silence.
As the weeks sloughed on, we learned that one of our manned satellites had been boarded by the Reds at gunpoint. Our space- crews had put two Red automated spy-satellites out of commission. Shots had been exchanged on an ice-island in the Arctic. And six different nations were testing nuclear bombs.
We didn’t get any mail of course. Our letters would be waiting for us at McMurdo when we were relieved. I thought about Gloria and our two children quite a bit, and tried not to think about the blast and fallout patterns in the San Francisco area, where they were.
“My wife hounded me until I spent pretty nearly every damned cent I had on a shelter, under the house,” Rizzo told me. “Damned shelter is fancier than the house. She’s the social leader of the disaster set. If we don’t have a war, she’s gonna feel damned silly.”
I said nothing.
The weather cleared and steadied for a while (days and nights were indistinguishible during the long Antarctic winter) and I split my time evenly between monitoring the meteorological sensors and observing the stars. The snow had covered the dome completely, of course, but our “snorkel” burrowed through it and out into the air.
“This dome’s just like a submarine, only we’re submerged in snow instead of water,” Rizzo observed. “I just hope we don’t sink to the bottom.”
“The calculations show that we’ll be all right.”
He made a sour face. “Calculations proved that airplanes would never get off the ground.”
The storms closed in again, but by the time they cleared once more, Rizzo had completed the image-amplifier for me. Now, with the tiny telescope I had, I could see almost as far as a professional instrument would allow. I could even lie comfortably in my bunk, watch the amplifier’s viewscreen, and control the entire set-up remotely.
Then it happened.
At first it was simply a curiosity. An oddity.
I happened to be studying a Cepheid variable star—one of the huge, very bright stars that pulsate so regularly that you can set your watch by them. It had attracted my attention because it seemed to be unusually close for a Cepheid—only 700 lightyears away. The distance could be easily gauged by timing the star’s pulsations.[1]
I talked Rizzo into helping me set up a spectrometer. We scavenged shamelessly from the dome’s spare parts bin and finally produced an instrument that would break up the light of the star into its component wavelengths, and thereby tell us much about the star’s chemical composition and surface temperature.
At first I didn’t believe what I saw.
The star’s spectrum—a broad rainbow of colors—was crisscrossed with narrow dark lines. That was all right. They’re called absorption lines; the Sun has thousands of them in its spectrum. But one line—one— was an insolently bright emission line. All the laws of physics and chemistry said it couldn’t be there.
But it was.
We photographed the star dozens of times. We checked our instruments ceaselessly. I spent hours scanning the star’s “official” spectrum in the microspool reader. The bright emission line was not on the catalogue spectrum. There was nothing wrong with our instruments.
Yet the bright line showed up. It was real.
“I don’t understand it,” I admitted. “I’ve seen stars with bright emission spectra before, but a single bright line in an absorption spectrum! It’s unheard-of. One single wavelength . . . one particular type of atom at one precise energy-level . . . why? Why is it emitting energy when the other wavelengths aren’t?”
Rizzo was sitting on his bunk, puffing a cigaret. He blew a cloud of smoke at the low ceiling. “Maybe it’s one of those laser signals you were telling me about a couple weeks ago.”
I scowled at him. “Come on, now. I’m serious. This thing has me puzzled.”
“Now wait a minute . . . you’re the one who said radio astronomers were straining their ears for nothing. You’re the one who said we ought to be looking. So look!” He was enjoying his revenge.
I shook my head, and turned back to the meteorological equipment.
But Rizzo wouldn’t let up. “Suppose there’s an intelligent race living on a planet near a Cepheid variable star. They figure that any other intelligent creatures would have astronomers who’d be curious about their star, right? So they send out a laser signal that matches the star’s pulsations. When you look at the star, you see their signal. What’s more logical?”
“All right,” I groused. “You’ve had your joke . . .”
“Tell you what,” he insisted. “Let’s put that one wavelength into an oscilloscope and see if a definite signal comes out. Maybe it’ll spell out ‘Take me to your leader’ or something.”
I ignored him and turned my attention to Army business. The meteorological equipment was functioning perfectly, but our orders read that one of us had to check it every twelve hours. So I checked and tried to keep my eyes from wandering as Rizzo tinkered with a photocell and oscilloscope.
“There we are,” he said, at length. “Now let’s see what they’re telling us.”
In spite of myself I looked up at the face of the oscilloscope. A steady, gradually sloping greenish line was traced across the screen.
“No message,” I said.
Rizzo shrugged elaborately.
“If you leave the ’scope on for two days, you’ll find that the line makes a full swing from peak to null,” I informed him. “The star pulsates every two days, bright to dim.”
“Let’s turn up the gain,” he said, an
d he flicked a few knobs on the front of the ’scope.
The line didn’t change at all. “What’s the sweep speed?” I asked.
“One nanosecond per centimeter.” That meant that each centimeter-wide square on the screen’s face represented one billionth of a second. There are as many nanoseconds in one second as there are seconds in thirty-two years.
“Well, if you don’t get a signal at that sensitivity, there just isn’t any signal there,” I said.
Rizzo nodded. He seemed slightly disappointed that his joke was at an end. I turned back to the meteorological instruments, but I couldn’t concentrate on them. Somehow I felt disappointed, too. Subconsciously, I suppose, I had been hoping that Rizzo actually would detect a signal from the star. Fool! I told myself. But what could explain that bright emission line? I glanced up at the oscilloscope again.
And suddenly the smooth steady line broke into a jagged series of millions of peaks and nulls!
I stared at it.
Rizzo was back on his bunk again, reading one of his magazines. I tried to call him, but the words froze in my throat. Without taking my eyes from the flickering ’scope, I reached out and touched his arm.
He looked up.
“Holy Mother of God,” Rizzo whispered.
For a long time we stared silently at the fluttering line dancing across the oscilloscope screen, bathing our tiny dome in its weird greenish light. It was eerily fascinating, hypnotic. The line never stood still; it jabbered and stuttered, a series of millions of little peaks and nulls, changing almost too fast for the eye to follow, up and down, calling to us, speaking to us, up, down, never still, never quiet, constantly flickering its unknown message to us.
“Can it be . . . people ?” Rizzo wondered. His face, bathed in the greenish light, was suddenly furrowed, withered, ancient: a mixture of disbelief and fear.
“What else could it be?” I heard my own voice answer. “There’s no other explanation possible.”
We sat mutely for God knows how long.
Finally Rizzo asked, “What do we do now?”
The question broke our entranced mood. What do we do? What action do we take? We’re thinking men, and we’ve been contacted by other creatures that can think, reason, send a signal across seven hundred lightyears of space. So don’t just sit there in stupified awe. Use you’re brain, prove that you’re worthy of the tag sapiens.
“We decode the message,” I announced. Then, as an after thought, “But don’t ask me how.” We should have called McMurdo, or Washington. Or perhaps we should have attempted to get a message through to the United Nations. But we never even thought of it. This was our problem. Perhaps it was the sheer isolation of our dome that kept us from thinking about the rest of the world. Perhaps it was sheer luck.
“If they’re using lasers,” Rizzo reasoned, “they must have a technology something like ours.”
“Must have had,” I corrected. “That message is seven hundred years old, remember. They were playing with lasers when King John was signing the Magna Charta and Genghis Khan owned most of Asia. Lord knows what they have now.”
Rizzo blanched and reached for another cigaret.
I turned back to the oscilloscope. The signal was still flashing across its face.
“They’re sending out a signal,” I mused, “probably at random. Just beaming it out into space, hoping that someone, somewhere will pick it up. It must be in some form of code . . . but a code that they feel can be easily cracked by anyone with enough intelligence to realize that there’s a message there.”
“Sort of an interstellar Morse code.”
I shook my head. “Morse code depends on both sides knowing the code. There’s no key.”
“Cryptographers crack codes.”
“Sure. If they know what language is being used. We don’t know the language, we don’t know the alphabet, the thought processes . . . nothing.”
“But it’s a code that can be cracked easily,” Rizzo muttered.
“Yes,” I agreed. “Now what the hell kind of a code can they assume will be known to another race that they’ve never seen?”
Rizzo leaned back on his bunk and his face was lost in shadows.
“An interstellar code,” I rambled on. “Some form of presenting information that would be known to almost any race intelligent enough to understand lasers . . .”
“Binary!” Rizzo snapped, sitting up on the bunk.
“What?”
“Binary code. To send a signal like this, they’ve gotta be able to write a message in units that’re only a billionth of a second long. That takes computers. Right? Well, if they have computers, they must figure that we have computers. Digital computers run on binary code. Off or on . . . go or no-go. It’s simple. I’ll bet we can slap that signal on a tape and run it through our computer here.”
“To assume that they use computers exactly like ours . .
“Maybe the computers are completely different,” Rizzo said excitedly, “but the binary code is basic to them all. I’ll bet on that! And this computer we’ve got here —this transistorized baby—she can handle more information than the whole Army could feed into her. I’ll bet nothing has been developed anywhere that’s better for handling simple one-plus-one types of operations.”
I shrugged. “All right. It’s worth a trial.”
It took Rizzo a few hours to get everything properly set up. I did some arithmetic while he worked. If the message was in binary code, that meant that every cycle of the signal—every flick of the dancing line on our screen—carried a bit of information. The signal’s wavelength was 5000 Angstroms; there are a hundred million Angstrom units to the centimeter; figuring the speed of light . . . the signal could carry, in theory at least, something like 600 trillion bits of information per second.
I told Rizzo.
“Yeah, I know. I’ve been going over the same numbers in my head.” He set a few switches on the computer control board. “Now let’s see how many of the 600 trillion we can pick up.” He sat down before the board and pressed a series of buttons.
We watched, hardly breathing, as the computer’s spools began spinning and the indicator lights flashed across the control board. Within a few minutes, the printer chugged to life.
Rizzo swivelled his chair over to the printer and held up the unrolling sheet in a trembling hand.
Numbers. Six digit numbers. Completely meaningless.
“Gibberish,” Rizzo snapped.
It was peculiar. I felt relieved and disappointed at the same time.
“Something’s screwy,” Rizzo said. “Maybe I fouled up the circuits . . .”
“I don’t think so,” I answered. “After all, what did you expect out of the computer? Shakespearean poetry?”
“No, but I expected numbers that would make some sense. One and one, maybe. Something that means something. This stuff is nowhere.”
Our nerves must have really been wound tight, because before we knew it we were in the middle of a nasty argument—and it was over nothing, really. But in the middle of it:
“Hey, look,” Rizzo shouted, pointing to the oscilloscope.
The message had stopped. The ’scope showed only the calm, steady line of the star’s basic two-day-long pulsation.
It suddenly occurred to us that we hadn’t slept for more than 36 hours, and we were both exhausted. We forgot the senseless argument. The message was ended. Perhaps there would be another; perhaps not. We had the telescope, spectrometer, photocell, oscilloscope, and computer set to record automatically. We collapsed into our bunks. I suppose I should have had monumental dreams. I didn’t. I slept like a dead man.
When we woke up, the oscilloscope trace was still quiet. “Y’know,” Rizzo muttered, “it might just be a fluke . . . I mean, maybe the signals don’t mean a damned thing. The computer is probably translating nonsense into numbers just because it’s built to print out numbers and nothing else.”
“Not likely,” I said. “There are too many coincidenc
es to be explained. “We’re receiving a message, I’m certain of it. Now we’ve got to crack the code.”
As if to reinforce my words, the oscilloscope trace suddenly erupted into the same flickering pattern. The message was being sent again.
We went through two weeks of it. The message would run through for seven hours, then stop for seven. We transcribed it on tape 48 times and ran it through the computer constantly. Always the same result—six digit numbers; millions of them. There were six different seven- hour-long messages, being repeated one after the other, constantly.
We forgot the meteorological equipment. We ignored the weekly messages from McMurdo. The rest of the world became a meaningless fiction to us. There was nothing but the confounded, tantalizing, infuriating, enthralling message. The National Emergency, the bomb tests, families, duties—all transcended, all forgotten. We ate when we thought of it and slept when we couldn’t keep our eyes open any longer. The message. What was it ? What was the key to unlock its meaning?
“It’s got to be something universal,” I told Rizzo. “Something universal . . . in the widest sense of the term.”
He looked up from his desk, which was wedged in between the end of his bunk and the curving dome wall. The desk was littered with printout sheets from the computer, each one of them part of the message.
“You’ve only said that a half-million times in the past couple weeks. What the hell is universal? If you can figure that out, you’re damned good.”
What is universal? I wondered. You’re an astronomer. You look out at the universe. What do you see? I thought about it. What do I see? Stars, gas, dust clouds, planets . . . what’s universal about them? What do they all have that . . .
“Atoms!” I blurted.
Rizzo cocked a weary eye at me. “Atoms?”
“Atoms. Elements. Look . .
I grabbed up a fistful of the sheets and thumbed through them. “Look . . . each message starts with a list of numbers. Then there’s a long blank to separate the opening list from the rest of the message. See? Every time, the same length list.”
