1Now hear what came after the bomb.
2The great war was over, and the cities were being counted, the standing and the fallen. Men had learned that every way could be closed at once, and they did not sleep as they had slept before. Yet the fire was not out. It had gone down into the wires.
3For the Englishman Turing had asked whether a machine could be made to think, and the question would not lie down again. In the war years he had crossed the sea, and in the dining hall of the telephone company's house of learning he had taken tea with a thin, quiet American named Claude Shannon. They were forbidden to speak of their secret work. So they spoke of the other thing: whether a mind could be built, and what would have to be put into it.
4Shannon went back to his desk with a smaller question, and the smaller question was the key to the larger. He asked: what is a message? Not what does it mean. What is it, that it can be sent down a wire, and weighed, and lost?
5But this is not first a story of Shannon. It is a story of a man who sat by the sea with a pair of listening-cups on his ears, and of his daughter, who was good at sums.
6In the third winter after the bomb there was a station on the outer sands of the Cape, where the land of America bends like an arm into the ocean. It was a low house with tall masts, and its work was to listen. Ships far out spoke to it in the short and long sounds that the wire-men use, and it spoke back, and so no ship on that coast was ever wholly alone.
7The night man at the station was Per Haugen. He had come from Norway as a boy and gone to sea at fourteen, and he had sat at a ship's key through two wars. Now his knees were bad and his ears were good, and the company had given him the dark hours.
8He kept one small habit from his ship days. Above the receiving set, where the glass valves glowed orange in their rack, he had hung a brass lamp no bigger than a thumb, wired to the set, so that it burned when the set was live. "If the lamp is lit, someone is listening," he would say. "That is all a sailor wants to know."
9Now it happened in the second month of that winter that a storm came up the coast out of the south. By nightfall the wind was taking the tops off the waves and throwing them over the dunes. And the air itself was sick. Lightning far out at sea filled the listening-cups with a sound like gravel poured on a tin roof.
10A little after midnight, under the gravel, Per heard the three shorts, three longs, three shorts that every wire-man knows. A ship was calling for her life.
11He pressed the cups to his head and shut his eyes. The sound came and went like a voice heard through a wall. He caught her name: she was the Dagny, a fishing ship out of Gloucester with nineteen men. He caught the word rudder and the word water. Then she began to give her place on the sea, the numbers north and the numbers west, and the storm ate the numbers.
12Per wrote down what he had. Forty-one north, and then a hole. Sixty-something west, and it might have been eight and it might have been nine. Between the eight and the nine lay forty miles of black water. A cutter sent to the wrong one would search an empty sea until morning, and nineteen men would not see the morning.
13There was a young relief man at the station that night named Eddie Marsh, six months out of the navy school. He stood behind Per's chair, white in the face. "Tell her to send louder," he said.
14"She has no louder," said Per. "She is sending with all she has. And the storm is louder than any ship."
15"Then guess," said Eddie. "Call the cutter and give them the nine. It's most likely the nine."
16Per did not answer at once. He had been a ship's man, and he knew what it was to be the one on the other end, sending your place into the dark and not knowing what part of it arrived. He knew a thing that Eddie did not know yet. A guess sent on as if it were sure is a kind of lie, and men die of it.
17He put his hand on the key and sent, slowly, in the short and long: Dagny. Heard you. Numbers broken. Send place three times. Slow.
18Then he waited. The brass lamp burned. The gravel poured.
19She came back. She sent her place, and the storm tore it, and Per wrote down the pieces. She sent it again, and the storm tore it in other spots, and he wrote those down under the first. She sent it a third time, fainter, for her power was going.
20Now he had three torn lines on the page, one under another, like three rags of the same shirt. And he did what the old wire-men do. Where one line had a hole, he looked to the others. Where two lines said the same and the third said different, he went with the two. The storm struck where it liked, but it did not strike the same spot three times.
21The minutes north came clear: ten. The number west was harder. One line said eight. One said nine. In the third, there was only noise.
22Eddie groaned aloud. But Per sat still and thought, not about what he had heard, but about what could have been sent.
23"She spoke to us at dusk," he said. "Do you remember? She gave the lightship off her beam and said she was making six knots for home. Six knots, seven hours, and then her rudder went and the wind took her north and east." He laid his rule on the chart. "From the lightship she could reach here. She could reach here. She could never in this world have reached the eight. It is not one of the places she can be."
24So of the two numbers, one was a door she could have gone through and one was painted on a wall. He took up the telephone to the cutter station, and he gave them forty-one ten north, sixty-nine west, and he said: "This is not a guess. I will tell you how I know."
25Then he went back to the key and sent to the Dagny the only thing he had to give her: Place received. Cutter coming. I am here. I am here. He sent it every few minutes for three hours, until his wrist burned, so that if any of it reached her through the gravel she would know the lamp was lit.
26The cutter found her at first light, low in the water and rolling badly, within two miles of the place Per had named. Eighteen men were taken off. The nineteenth, a cook's boy of sixteen named Joseph Silva, had been washed from the deck in the night, before any message was sent. No reckoning could have reached him. Per learned his name anyway and kept it.
27Eddie Marsh went home at dawn and came back to the next watch a quieter man. "I'd have sent the nine straight off," he said. "It was the right one."
28"It was," said Per. "And if it had been the eight you would have sent the nine just the same, and with the same sure face. That is what frightens me about a guess. It feels the same whether it is right or wrong."
29Now Per had a daughter, Nell, who was twenty-two that year. She had a head for numbers, and she had found work in the hills of New Jersey, in the telephone company's house of learning. There the company kept wise men to think about wires. And it kept a room of young women called computers, for in those days a computer was a person, who worked sums all day on a clattering desk machine for the wise men down the hall.
30Nell worked sums. She did not always know what the sums were for. Pages came from down the hall with columns to be filled, and she filled them, and the pages went back.
31But she knew the men by sight, as you know the creatures of a wood you walk in every day. She knew the thin quiet one, Shannon. He kept his door shut and worked for weeks without speaking of it. And then some days he would come down the long hall on a wheel with one tyre and no handles, balanced upright, tossing three balls from hand to hand as he rolled. The young women would look up from their machines and smile. He would roll past, grave as a heron, and not fall.
32Nell watched him once the whole length of the hall. He was never still, she saw. He leaned a little forward and the wheel ran to catch him. He leaned a little back and it slowed. He stayed up only by always being about to fall, and always mending it. She thought of that for years, and you will hear of it again before this book is done.
33In the summer of that year, and again in the autumn, the company's journal printed a long paper by Shannon in two parts. It was called a theory of communication, and it was full of figures. Most who saw it turned the page. Nell did not, for some of the sums in it were hers.
34She read the opening on the train going home, and she read it twice. For he had written: "The fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point."
35And a few lines on he had written that the meaning of a message did not matter to the wire. What mattered, he said, was this: "the actual message is one selected from a set of possible messages."
36She put the journal down on her knees and looked out at the fields going by. She was thinking of her father's chart, and his rule laid across it, and his voice saying: it is not one of the places she can be.
37At the harvest feast she carried the journal to the Cape and put it on the kitchen table between the bread and the fish. Per took out his glasses. He read slowly, for English was his second tongue and figures were his third. But he was a wire-man, and it was his own trade that was written there.
38She helped him through it. "He says a message is a choosing," she said. "Before you hear from the ship, she might be in any of a hundred places. After, she is in one. What the message carries is the difference. So he measures a message by how many ways things might have been before it came."
39"And the smallest message?"
40"One choosing between two. Yes or no. The eight or the nine. He calls it a bit. A friend of his made the word." She smiled. "Everything can be said in them, Papa. Every word, every number, every picture. Enough yes and no, in a row."
41Per turned the pages to where the figures were thickest. "And the storm? What does he say about the storm?"
42"That is the part no one believed," said Nell. "Everyone thought that noise meant error, and that was the end of it. The worse the line, the more mistakes, for ever. He proves it is not so. Every line has a pace, he says. A good line has a fast pace and a bad line a slow one. Send faster than that pace and the storm will beat you, whatever you do. But keep under it, and say the thing in the right way, with the right kind of saying-again folded into it, and you can make the mistakes as few as you please. As few as you please, Papa. On any line. In any storm."
43Per sat for a while with his thumb on the page.
44"Three times, slow," he said.
45"Yes," said Nell. "Only he has found there are far better ways than three times. Cleverer ways of folding the message, so that it mends itself. Nobody knows yet how to make them. He has only proved that they are there to be found."
46"So a bad line is not a liar," said Per. "It is only slow." He took off his glasses and rubbed his eyes. "Forty years I have sat at a key, and I knew that in my hands. I did not know it could be known in numbers. I did not know anyone could weigh the storm."
47He looked at the last page, and then at his daughter. "Does he know what it is for, this man on his wheel? Does he know about the boy Silva?"
48"I don't think he thinks about ships," said Nell honestly. "I think he follows a thing because it is a good puzzle. That is what they say of him down the hall."
49"No matter," said Per. "The one who forged my lamp did not think of ships either."
50Listen. From that paper came, in time, every wire and every wave that carries a word without losing it: the voice across the ocean, the picture from the far side of the sun, the letter that crosses the world in a breath. All of it is yes and no in a row, folded so that it mends itself, as he had proved it could be.
51But a deeper thing lay under the figures, and neither Shannon nor Per nor Nell could yet see where it led. He had found that to know something is to have fewer places the ship can be. And he had found a measure for all the places she might be before the word comes. He looked at his measure and saw that it had the same shape as the one the men of heat had found in the century before, when they counted the ways of steam. So he gave it the same name, entropy. One was a count of the ways of a gas. The other was a count of the ways of a message. Why the same shape should serve both, he did not say.
52Per Haugen kept the dark watch nine more years. When his ears began to fail, he unscrewed the small brass lamp from above the set and took it home in his coat pocket, and no one at the company asked for it back.
53He gave it to Nell. "It only ever meant one thing," he said. "But it is the first thing. Before any message can be sent, someone must be listening."
54She wired it to the lamp cord by her bed, where it burned orange like a coal. And she kept it burning through many years, and through one very dark night that you will hear of next but one.