The Surprise Meter

The first thing Maya and Soren sent to the Moon came back as an error.

Not a red error. Not angry. Just a neat gray box on the museum table that said, MESSAGE TOO LARGE, and then, almost politely, TRY A LESS SURPRISING POSTCARD.

Maya leaned closer.

"It does not get to say that," she said.

Soren had already written the sentence down, because a machine calling a postcard surprising was the sort of thing that made the inside of his head feel crowded.

The Moon table stood in the center of the Hall of Messages. Above it, a laser link counted down to the next clear window with the lunar education station near Shackleton Crater. On the wall screen, the station's little printer waited under a glass dome, its paper strip curled like a tongue.

Aunt Leena, who was not actually Maya's aunt but had told everyone to call her that because her real title took too long, was trying to fix three things at once. She had a screwdriver in her hair and a coil of fiber cable around one elbow.

"Pick one of the menu postcards," she said. "Smiley moon. Earthrise. Rocket. The relay window is short, and the children before you used most of the practice time drawing cats. Beautiful cats. Very expensive cats."

Maya looked at the menu. Sixteen cheerful pictures blinked in boxes.

"No," she said.

Soren did not look up from the table. "Her triangle almost fit. It failed at the last part."

"It was not a triangle," Maya said.

On her screen was a black triangle with a white triangle cut from its middle. In each black corner, the same thing happened again, smaller. And again. And again, until the screen gave up drawing the tiny edges and turned them silver.

"It is a triangle that keeps leaving room," Maya said.

Aunt Leena glanced over, smiled too quickly, and turned back to the cable. "Lovely. Also large. The Moon does not care how lovely. It cares how many bits."

The table had three glass columns beside the keyboard.

One was labeled RADIO.

One was labeled HEAT.

One was labeled PROGRAM.

When Soren pressed the test key, the RADIO column filled with blue beads. Each bead was one bit the laser had to carry.

He typed AAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.

The table chirped. The blue beads barely rose.

"That is unfair," Maya said.

"No," Soren said. "It guessed. Lots of As are easy to describe."

He typed QLZAPXMVDKTRN.

The blue beads jumped.

Maya narrowed her eyes. "It did not like that."

"It could not guess it," Soren said.

"So guessing is part of sending."

Soren tried the menu postcard for Smiley Moon. Four blue beads rolled into the RADIO column.

Maya sent her triangle again. The blue beads climbed, paused, climbed more, then spilled over the marked line.

MESSAGE TOO LARGE.

TRY A LESS SURPRISING POSTCARD.

Behind the glass of the HEAT column, a red light flickered. It was too small to warm the room. A label said the light was scaled up from the smallest heat a computer must give off when it erases bits.

Soren tapped the label.

"Same count," he said.

"What?"

"When the table throws away wrong guesses, the heat column moves with the bit column. Not much in real life. It says scaled. But the numbers match."

Maya put her finger against the glass. The red flicker stepped when the blue beads stepped.

Aunt Leena came back, took the screwdriver out of her hair, and frowned at the countdown.

"Four minutes," she said. "Please pick the smiley moon. Everyone enjoys the smiley moon."

"Because it is expected," Maya said.

"Exactly."

"That is why it is cheap."

Aunt Leena stopped with the screwdriver halfway to her pocket.

Soren turned the screen toward her. "The table is not measuring prettiness. It is measuring how surprised the receiver will be. If the receiver already expects the message, almost nothing has to travel."

"That is the point of the exhibit," Aunt Leena said. "Very good. Menu now."

Maya did not move.

On the code panel, every menu postcard had a short code. The smiley moon was zero zero. Earthrise was zero one. Rocket was one zero. Cat, because of the earlier children, had somehow been added as one one zero.

Below them was a gray row marked OTHER.

No code.

Maya touched it.

"This one is empty."

"We cut it," Aunt Leena said. "OTHER wastes space. For a public demo, you want the likely choices."

Soren looked at Maya's triangle. Then he looked at the PROGRAM column, which had not moved much at all.

"Wait," he said.

Maya grinned. "Say it slower."

"The picture is big if we send every dot," Soren said. "But it is not random. It is made by a rule. The Moon printer can run rules. That is why there is a program column."

He opened the command list. LINE. TURN. REPEAT. CUT MIDDLE TRIANGLE. STOP WHEN TOO SMALL.

Maya's hands were already on the keys.

Aunt Leena made a small sound. "That command set is for the advanced demonstration."

"Good," Maya said.

"It may not fit either."

"Then we change the code," Soren said.

He pulled up the choices waiting in the queue. Most visitors had picked smiley moon. A few had picked Earthrise. One had picked rocket. No one had picked cat again, which seemed to disappoint the table.

Soren shortened smiley moon to zero. Earthrise became one zero. Rocket became one one zero. The triangle rule became one one one zero. OTHER became one one one one.

"That is not balanced," Aunt Leena said.

"Neither are the choices," Soren said.

Maya pressed TEST.

The RADIO beads climbed, but not to the line.

The HEAT light flickered in the same little steps.

The PROGRAM column began to glow green.

On the simulation screen, the Moon printer received the short code, unfolded the rule, and drew a triangle. Then it moved inside the triangle and made another absence. Then another.

The screen filled with edges that came from almost nothing.

The line behind them went quiet.

Maya did not say anything. Soren did not either. The table was saying enough. The strange picture had not been too much because it was strange. It had been too much when they tried to send it the wrong way.

Aunt Leena looked from the countdown to the green test mark. Her face did the adult thing where no changed into maybe and tried to pretend it had been maybe all along.

"Checksum?" she asked.

Soren ran it. "Green."

"Receiver dictionary?"

Maya checked. "Matched."

"Escape code?"

"OTHER is back," Soren said.

Aunt Leena pointed the screwdriver at him. "If the Moon sends nonsense, that is on you."

"If it sends something we did not make room for," Maya said, "we will never know."

The countdown reached ten.

Aunt Leena stepped back from the table. "Then send your unlikely triangle."

Maya and Soren pressed the key together.

Nothing dramatic happened in the room. No thunder. No shining beam anyone could see. The RADIO beads dropped through their glass throat in a quick blue rain. The HEAT light gave its tiny red shiver. The PROGRAM column brightened as the lunar printer woke.

On the wall screen, the paper strip under the glass dome jerked once.

A black line appeared.

Then a second.

Then a third.

The printer paused, turned, and began removing the middle of what it had just made.

The room exhaled all at once. The triangle grew by leaving pieces out. The less the printer filled, the more there seemed to be. Each blank place pointed to smaller blank places. The paper strip curled forward, black and white and black and white, a message made from rule and silence.

Then the return screen blinked.

STATUS FROM LUNAR STATION.

OK lit green.

PAPER MOVING lit green.

INK LOW stayed dark.

At the bottom of the list, in the slot Maya had touched, the square beside OTHER turned blue.

Aunt Leena said, "That should not have anything to say."

The blue square blinked again.

On the Moon camera, the little printer kept tapping.