Camouflage

—28—

The idea of signaling alien intelligence with a message that didn’t depend on language went back to 1820: the mathematical genius Carl Friedrich Gauss suggested clearing an immense section of Siberian forest, and then planting wheat in three squares that would diagram the Pythagorean theorem. An observer on Mars would be able to see it with a small telescope.

There were other schemes in the nineteenth and twentieth centuries, involving mirrors reflecting sunlight, huge fires demonstrating geometrical shapes, or cities blinking their lights on and off.

Around 1960, Mars no longer a compelling target, Frank Drake and others suggested an elaboration of this “Morse code” approach that would be visible from interstellar distances, using radio telescopes as transmitters rather than antennas, sending out a tight beam of digital information. The reasonable assumption was that any civilization advanced enough to receive the message would be able to understand binary arithmetic. So they sent, in essence, a series of dots and dashes that said “1 + 1=2,” and went on from there.

The idea was to establish a matrix, a rectangle of boxes that would make an understandable picture if you made some of the boxes (corresponding to “1”) black and left the others (corresponding to “0”) white— like a crossword puzzle before it’s filled out.

For it to make sense, you had to know the dimensions of the rectangle. The easiest way to do it would be to broadcast the information one line at a time, with pauses between the lines. Then a longer pause, and repeat the same thing over, for verification.

That does take a long time. Drake suggested that a single long string of ones and zeros would suffice, if there were some way to tell how many of them made up each line.

Prime numbers were the answer. Any pair of prime numbers, multiplied together, produces a number you can’t arrive at with any other pair. The number thirty-five can only come from seven times five, so a sufficiently clever alien could look at this string of ones and zeros:

and come up with this rectangle:

Of course a five-by-seven rectangle is just as likely, but gives this:

—which we would hope is not insulting in the alien’s language.

With a large enough number of spaces, the difference between order and chaos is obvious. Drake’s example was 551 characters, which made a map twenty-nine by nineteen spaces. Of course it didn’t spell out an English word; in fact, it was meant to be an incoming signal: it showed a crude drawing of an alien creature and a diagram of its solar system, along with other shapes that indicated it was carbon-based life, that it was thirty-one wavelengths tall, and that there were seven billion individuals on its planet—and three thousand colonists on the next planet in, and eleven explorers on the next one.

The message Jan would send the artifact used the same technique, though it could be much more elaborate, since the receiver was inches away rather than light-years. Starting with the same arithmetic and mathematics, it went beyond a stick-figure- plus-DNA diagram to present digital representations of Einsteinian relativity, photographs of several different people, a Bach fugue, one of Hokusai’s views of Fujiyama, and Vermeer’s Girl with a Pearl Earring in black and white.

The signal took about fifteen minutes to transmit. Focusing on various parts of the artifact, they beamed it in every frequency from microwave to X ray; they tapped it out mechanically on the thing’s surface. Of course there was no way of predicting what its response would be. Maybe it was responding in some way they couldn’t detect— saying “Shut up and give me some peace!” It was reasonable, though, to expect that it would respond in a way similar to the message: light or sound in a similar binary sequence.

Of course it might just be a dumb machine, capable of moving itself out of harm’s way, and nothing else.

After two weeks of no results, Jan was discouraged. She asked Russ and Jack to meet her at the Sails for dinner and strategy.

The two men showed up together just as the sundown storm started. The setting sun was a dull red ball on the horizon while sheets of rain marched sideways across the harbor. No thunder or lightning; just an incessant downpour.

“Another wonderful day in paradise,” she said.

“E.T. hasn’t phoned home?” Jack said as he sat down.

“Got ‘call waiting.’ ” The waiter appeared with the wine list. Jack waved it away and ordered a bottle of Bin 43.

“So what do you think?” Russ said.

“Oh, I don’t know.” She refilled her coffee cup from a silver thermos flask. “I guess it’s time to move on to the planetary environments phase. If it reacts to anything, I can repeat the Drake algorithm then.” She sipped the coffee. “As you say, Russ, maybe it’s asleep or in some dormant mode. Maybe if we reproduce its home planet’s conditions, it will be more inclined to talk.”

Jan winced as a shift of wind sent a fine spray over them. “Waiter,” Jack said, standing and pointing to a table just inside. He carried Jan’s coffee flask in, and while a woman lit candles, the waiter appeared with a bottle and three glasses.

“I’m willing to be patient,” Jack said, going through the tasting ritual.

“It’s not a matter of patience.” She put her hand over her wineglass. “I feel as if we’ve gone as far as we can in this direction.”

“Well, we knew it was going to be all or nothing,” Russ said. “Just one peep out of the thing and we’d be …” He rose an eyebrow and took a sip of wine.

“Yes, we would,” she said. “But we’re not. Let’s move on.”

“Starting at square one?” Jack said. “Mercury?”

“We could start anywhere,” Russ said. “Mercury is going to cost out better. Just hot vacuum.”

“So there’s a decision?”

He looked at Jan. “Acoustic. We want to continue tapping out your message on the thing’s surface. If it responds acoustically, we won’t hear it in a vacuum.”

“We can run a taut wire from it,” Jack said, “like a tin-can telephone.”

“Hard to get it through the wall without damping vibrations.”

Jack shrugged. “So don’t run it through.” He spread out his napkin and clicked a pen open. He drew a square inside a square and attached the inner to the outer with springs. “See? You have your taut wire pulling on the back of this”—he tapped the inner square—“and it acts like an old-fashioned speaker. It’s gonna vibrate in a way that mimics the artifact’s vibrations.”

“But we still can’t hear it,” Jan said.

“Ah, but we can watch it. Draw a grid on the square and put a camera on it.”

“Fourier transforms,” Russ said with approval.

“Duck soup,” Jack said.

“We have no duck,” the waiter said. He was standing behind Jack’s shoulder. “We have clam chowder or chicken with mushrooms.”

Russ looked at him and decided he wasn’t joking. “I’ll have the chowder and grilled masimasi.”

“Me, too,” Jan said.

“The usual,” Jack said.

“Cholesterol with cholesterol sauce,” Jan said.

“You will have a red wine with that?”

“Bin 88,” Jack and Russ said simultaneously. “And I want it really blue this time,” Jack said of his steak. “Cold in the center.”

The waiter nodded and left. Russ imitated his accent: “Sir, we cannot guarantee that you will survive this meal. Samoan cattle have parasites for which there are no Western names.”

Jack smiled and refilled both glasses of white wine. “Mercury, and then go on to Mars? Vacuum with a little carbon dioxide. Then Venus and the gasbags.”

“Good name for a rock band,” Russ said.

“Titan?” Jan said. “Europa?”

“Makes sense,” Russ said. “And just outer space, 2.8 degrees above absolute zero. It probably spent a long time in that environment.”

“Hold on,” Jan said, and took an old computer out of her purse. She unrolled the keyboard and pulled out the antenna and typed a few words. “Let’s be methodical here. Starting with the mercurian environment.” They got halfway through the solar system before dinner came, and finished it over sherry and cheese, mapping out a rough schedule. They would spend five days with each environment, and one to four days in transition.

Hot Mercury, cool Mars, hellish Venus, cold poison Titan, arctic Europa, then the jovian model: high-pressure liquid hydrogen and helium, flowing at about 150 meters per second, flavored with methane and ammonia.

Jan took a sip of sherry and scrolled through the schedule. “Something bothers me.”

Jack nodded. “The pressure chamber’s—”

“No. What if the thing misunderstands? What if it thinks we’re attacking it?”

Russ laughed nervously. “I thought I was the anthropomorphic one.”

“If it does its little jump-off-the-pedestal trick while it’s in the Jupiter simulation…”

“Be worse than a daisy-cutter bomb,” Jack said. “Flatten everything out to here. They’ll hear it in American Samoa.”

“In Fiji,” Russ said. “Honolulu.”