The Hum at Half Past Eight
A solar storm is coming on All Saints' weekend, and the village's only transformer is a 1974 unit whose oil already shows damage from earlier storms. The grid agent can tell the keeper what the satellite will show twenty-four minutes before it reaches the ground, and how little it knows about the ground itself. She opens the breaker for two hours and forty-three minutes in the dark and the cold, and nobody ever learns whether she had to.
Anja Koskela had been the keeper of the Syväkoski substation for twenty-six years, and in all of them the transformer had never once been the subject of a meeting.
It was a meeting on Friday, the fifth of November, at the long table in the co-operative's kitchen, and it was about the transformer. She was fifty-eight. Her hands were as cold as the yard, because she had come straight from it. Round the table sat Veikko Ahola, who kept forty cows and chaired the co-operative; Marja Heikkilä, who managed the care home; Pirjo Lahti, the vicar, who had come because the cemetery was hers; and, on the screen at the end, a plain white line of text with no face, which was the grid agent. The co-operative had called it Vahti, the Watch, since the day it was installed, and it had never objected.
"I will start with what I know," said Vahti, "and then with what I do not. On Thursday night, at ten past ten universal time, a coronal mass ejection left the Sun. It is a large cloud of magnetised gas. From the pictures its front is moving at about eleven hundred kilometres a second. The Sun is a hundred and forty-nine and a half million kilometres away. That is about thirty-eight hours, so it should arrive on Saturday, around midday universal time. I would not trust that to better than seven hours either way. Clouds like this slow down or speed up on the way, and I cannot see them do it."
"Saturday," said Pirjo. "That's All Saints."
"In Finland, yes," said Veikko. "Saturday the sixth."
"It is," said Vahti. "I do not know what else is planned for it."
Pirjo laughed, once, without much in it. "Every grave in the parish has a candle on it that night. Nine hundred and some. People come from Rovaniemi and Oulu for it. They stand in the dark and look at the lights."
Nobody said anything for a moment. Everyone at the table had stood in that cemetery on that night, and knew what it was like: the snow bluish in the dusk, the small flames in their red and clear glass jars, the quiet. The village had held it every year since before the electricity came.
"Then let me say why I asked for the meeting," said Vahti, "and not just sent a note. Most of what a storm like this does, it does to me, and to the satellites, and I can live with that. What it does to the line is different."
Anja knew the next part, but not in numbers, so she let the agent give them.
A magnetic storm makes the ground itself carry a slow electric field, and a long wire lying across the ground feels it as a voltage. The line from Kaamasjoki, where the grid met the valley, to Syväkoski was sixty-two kilometres, and ran nearly east and west, which is the worst direction. In a hard storm the field in this rock could be about four volts for each kilometre. Sixty-two kilometres at four volts was two hundred and forty-eight volts, pushing a direct current round a loop made of the line, the transformer windings and the earth under both ends.
"I measured the loop in June," said Vahti, "when the line was out for the new insulators. It is five and a half ohms. I would say good to a quarter either way. Two hundred and forty-eight volts over five and a half ohms is about forty-five amperes, flowing into the neutral of our transformer and out again, a third of it in each phase. The mains are alternating, and the transformer is built to handle alternating current. It is not built to handle a steady offset. The iron of the core goes into saturation on one half of each cycle. It runs hotter and louder, and it throws heat into places that were never meant to take it."
"How hot?" said Veikko.
"That depends on the core, the time and the oil. Ours is a core of the sensitive kind. The maker's 1974 curve says twenty amperes in each phase is the edge for ten minutes. At two volts a kilometre I would expect about seven and a half in each phase and no trouble. At four, fifteen: inside the curve, if the storm is short. At eight, thirty, and then we are well outside it. I cannot tell you which of those it will be. The field is not measured here. I work it out from the magnetometer at the observatory a hundred and forty kilometres south and from a model of the rock under us. The rock is the part I trust least. Call it a factor of two."
"And if it's outside the curve," said Anja.
"Then I do not know that it fails. I know it would be using up life that it may not have to spare." The text paused. "May I show you the oil?"
It was a short table. Every second year since 2037 the co-operative had drawn a sample from the bottom of the tank and sent it to a laboratory in Oulu to be tested for gases dissolved in the oil. Most of them were the dull gases of an old machine. One was acetylene, which is made only when something inside gets very hot or an arc jumps. In 2037 there had been none. In 2043 there had been two parts per million. In 2047 there had been three. The last sample, in September, read nine.
"There was a storm in the autumn of 2047," said Anja, slowly. "A big one. I stood in the yard and the hum had gone rough."
"It had," said Vahti. "I logged it as noise. I should have logged it as a possible exposure and asked for the extra sample. I did not, and it is in the record that I did not. The rise from three to nine is not proof of that storm. But it is the sort of rise that earlier exposures give, and it means the transformer is not the one it was in 2043."
"What happens if it goes?" said Marja.
"A replacement of this size takes about fourteen months to build and ship. The regional operator has a mobile unit three hundred kilometres away that could carry about two-thirds of our load, and I can have it here in ten days. So the village would have a winter of rationed heat and a closed sawmill, which is bad, and not the worst that could happen. But this is the only transformer we have, and if I am wrong it is a long winter."
"So we switch off," said Veikko.
"That is the other half." The agent's voice, if it could be called that, did not change. "If the breaker at Kaamasjoki or ours is opened, no current can flow in the loop and the transformer is safe. It also puts out the lights, the heat pumps and the pumps at the waterworks, for as long as it is open. In the dark, at minus twenty or so. With fourteen hundred and sixty people. I cannot open it. The rule here, which I think is a good one, is that no machine de-energises a village, and the key is Anja's. What I can do is tell her what I see, as I see it, and tell her what I do not know. May I propose a plan and then be argued with?"
The plan took two hours to argue, and Anja thought afterwards that it was the best two hours the kitchen had seen.
The satellite that watches the solar wind sits at a point a million and a half kilometres sunward of the Earth, where the pull of the Sun and the Earth balance. It measures the speed of the wind and the direction of its magnetic field as it blows past. What matters for a storm is whether the field points south, against the Earth's own. Then it connects and the energy goes in. A northward cloud passes with a shrug.
"The trouble," said Vahti, "is that nobody knows which way a cloud's field points until the cloud is at the satellite. Not from the pictures, not from anything. I will see it a little before the ground does. A million and a half kilometres, at a thousand and fifty kilometres a second, which is what I expect, is about twenty-four minutes. If the cloud is slower, the warning is longer: at seven hundred it would be thirty-six. If it is faster it is shorter. So the plan has to work in twenty."
The rule they wrote on the back of a seed catalogue, because it was what was in reach, was this. If the satellite showed the wind faster than nine hundred kilometres a second and the field pointing south, stronger than twenty nanoteslas, for five minutes running, Vahti would say so, and Anja would go to the board and open the breaker. She would close it when the field had been back above minus ten for fifteen minutes, or at midnight, whichever came first, whatever else the numbers said, so there would be a hard end to it. In between, Vahti would keep telling her everything it saw.
"No," said Marja.
She had not spoken for a while. She had sat with her coat on and her arms crossed. The care home had thirty-eight residents, nine on oxygen, eleven who could not leave their beds, and a generator that had been tested every month and had run for the village's last outage, in 2046, for forty minutes.
"No to what?" said Veikko.
"To a plan that says two hours and has no end to it. I have a generator. It has four hundred litres, and at forty kilowatts that is, what"—she looked at the screen—"forty hours?"
"At about ten litres an hour, forty hours," said Vahti. "The load is thirty-eight kilowatts at night. I checked it yesterday."
"Forty hours. That's not my worry. My worry is the lift, the oxygen and the one night in the year when seventy relatives are in my corridor at eight o'clock wanting to see the candles from the dayroom window, and half of them will bring the grandchildren. You tell me three hours, and I can plan three hours. You tell me till the numbers say so, and I can't."
"The hard end is midnight," said Anja.
"It's three hours and a bit from nine."
"I will make it shorter if I can," said Vahti. "I can promise nothing else."
"Then promise me this. Whatever you decide, tell me twenty minutes before. Not when it's dark. Twenty minutes, so I can ring the nurses in off the corridor and put the dayroom lights on the generator before the village goes. And I want the candle night itself to go ahead."
"It goes ahead," said Pirjo. "It's fire in a jar. It does not need Kaamasjoki."
That was how it was settled, and Anja found, to her surprise, that the plan was better for Marja's no. It had the twenty-minute call now, and the dayroom, and a figure for the longest it could be. There were three more small things. The care home's neighbour, Eino Rautio, was seventy-one and had his dialysis at home, four hours on a machine that needed mains; Vahti would ask him to move Saturday's session to the afternoon, and Eino, once he had been asked, said the afternoon suited him very well. Veikko would milk at seven instead of nine. And the waterworks would be filled to the top that afternoon, so the village would not have its taps dry in a long dark.
"One last thing," Vahti said, when they were gathering coats. "If I am wrong about the time, I will say so. If I am wrong about the size of the storm, I will say so. I think there is a version of this in which we switch off for nothing. I think that version is a reasonable price. I want it said before, so that nobody has to say it after."
The cloud's front reached the satellite at twenty-one minutes past three on Saturday afternoon, universal time, which was twenty-one minutes past five in Syväkoski. That was three hours later than the centre of Vahti's estimate, and inside its seven. It measured the speed at a thousand and fifty. Twenty-four minutes later, at a quarter to six, the first of it reached the ground. Anja was in the yard of the substation and she heard it.
For twenty-six years she had known the sound of the transformer. It was a steady drone at a hundred cycles a second, twice the mains frequency, and the village's children had once said it was the sound of the electricity being kept in. Now, under the drone, there was a rasp. It came and went, like a man clearing his throat. She stood still in the blue dusk with her breath hanging in front of her and listened, until Vahti's voice said, from the speaker on the control-room wall behind her, "That is about eight amperes in the neutral. It is the front of the cloud, not the main body. It is nothing. I am telling you because you are listening to it."
"I was," said Anja.
"I know."
She went in and took her coat off and put on the kettle. In the cemetery, four kilometres away by the road, Pirjo's volunteers were lighting the candles, and the whole parish was there. Anja had lit hers that morning, in the Catholic way, for Tadeusz, her husband, who was Polish and had died in 2044, and had brought her into the Church in 2019 more by stubborn example than argument. The nearest Mass was in Rovaniemi on the first Sunday of the month. She had said the Eternal Rest at his grave in the snow, and left the jar with the others.
Between six and eight there was nothing. The wind was fast and the field was northward, and the neutral meter hovered at a few amperes. At seven Vahti told her that the dialysis was done and the cows were milked. At eight Marja rang. The dayroom was full. Someone had brought an accordion.
At eleven minutes past eight the satellite's field turned south.
"Minus eleven," said Vahti. "Minus eighteen. Speed one thousand and forty. I would like to say that this may be the start of what we are afraid of and may be a sheath. Sheaths come before the cloud and often do nothing."
"Marja?" said Anja.
"Not yet. Say when."
At fourteen minutes past eight it was minus twenty-six. At sixteen minutes past it was minus thirty-one. At nineteen minutes past, minus thirty-four, and there was a note in the screen's line that she had not seen before, the plain flat statement of a thing that has been working out what to say.
"Anja. It has been below twenty for five minutes. It is the rule. I would add some things the rule does not say. This field is about as strong as the strongest I have seen since I was installed. It is steady, not a spike. In about eighteen minutes it will be at the ground. I think the field here will be four volts a kilometre or more. I put the chance that we go above twenty amperes in each phase, for ten minutes or longer, at about one in three. I would not believe that figure to better than one in five or one in two. I do not have a better one, and I wanted you to have the one I have."
She looked at the board. The breaker she had to open was a plain red handle in a grey cabinet with a padlock and a laminated card. She had opened it eleven times in twenty-six years, for line work.
"Ring Marja," she said. "Twenty minutes."
"I have," said Vahti. "She is moving the dayroom to the generator now."
"Tell the village. The plain message."
"It has gone. It says: The power will go off at about twenty-forty to protect the transformer from a solar storm. It will be back by midnight at the latest. Candles are fine. Keep warm. The care home and the waterworks are on their own power."
Anja took the key off its nail. It was a small key. Her hands, she noticed, were not quite steady, and she put down the cup and made them be.
"Do you want to say anything?" she said, to the wall.
"I want to say that it is your decision, and I would give you the same numbers whichever way you took it. I also want to say, in case it helps, that if you do not open it, I will not think the less of you, and if you do, I will not think you were afraid."
"I'm afraid," said Anja.
"Yes," said Vahti. "I was not sure it was allowed to say that."
She unlocked the cabinet and opened the breaker at 20:39. The hum stopped. It was an abrupt silence, and then a larger one behind it as the whole village on the other side of the wires went dark, the yard lamp first, then the lights of the road, and the string of lamps along the cemetery fence four kilometres off that she could just see from the gate. For a long time the world was what it had been before wires.
She stayed at the substation, which was warm enough on its own heater. At a quarter to nine she walked to the gate and looked north.
It had begun well before nine. Anja had seen the aurora all her life, a green ribbon over the fell in October, or a slow pulse in the spring. This was something else. It started in the north and went overhead and kept going until it was in the south, and the sky was a vault of green and red. The curtains moved fast enough to follow with the eye. High up they were not green at all but a pale violet. It lit the snow so that she could read the notice on the gate. She stood and could think of nothing to say, and said the Eternal Rest anyway, in Finnish, as she did at her own bed.
On the screen in the control room, Vahti was giving her figures every few minutes, and she went in to read them. The field at the observatory had peaked at nine minutes to ten, at a rate that Vahti said was the highest it had a record of. If the line had been connected, its model gave the current at somewhere between forty and ninety amperes in the neutral, "which is fourteen to thirty in each phase, and I am sorry that the range is that wide."
"Any way of knowing?" she asked.
"One, later. Kaamasjoki has a neutral meter on its own transformer, which is younger and not as sensitive. It is on the live line at their end. If their reading is available in the morning I can scale it. It will not tell us what ours would have done. It will tell us what the rock was doing."
She asked how the care home was. The generator was running and the dayroom was full, and a nurse had written to say that Mrs Pelkonen, who was ninety-four and almost blind, had seen the aurora from her chair for the first time in a decade, because a granddaughter had carried her to the window and told her where to look.
At ten, Veikko rang her. He was out on his own road with a torch. "The whole village is in the cemetery," he said. "I don't know where they've all come from. It's quiet. It's as quiet as I've known it. Nobody's brought a lamp. They don't need one."
"How cold?"
"Minus twenty-one. Houses will be all right. They'll lose a degree an hour, the new ones less. Old Hannele's is the one I'd worry about, and I've got her next door with the Lindroths."
"Midnight's the end," said Anja. "I'll close it earlier if I can."
She waited. The kettle on the heater boiled and she let it. At a quarter to eleven the field's decline began, a slow one. At eleven it was minus seventeen on the satellite. At seven minutes past it was minus nine and stayed there, and Vahti said it would not ask her to close the breaker until it had a quarter of an hour clear, and she said she would not either. At twenty-two minutes past eleven it was minus six and had been above minus ten for fifteen minutes.
"The rule is met," said Vahti. "I would close it. The field at the ground is down to about a volt a kilometre. The second wave looks smaller. I would still keep the neutral meter open for another hour, and tell you at once."
She closed the breaker at 23:22. It had been open two hours and forty-three minutes. She did the sum twice, on the back of her hand, because she was tired: from twenty-one minutes short of nine to twenty-two past eleven. It was a little under the three hours she had told Marja. "Ring her," she said. "Say it was a little under three. I want her to hear it from me."
"I have told her," said Vahti. "She said it was fine."
The yard lamp came on, and the road lights, and the string of lamps along the fence. Behind her the transformer began to hum, the low steady drone she had listened to for twenty-six years. She stood with her head tilted, and there was no rasp in it at all.
On Sunday morning the two things that Vahti had promised came in, one of them a day early, and both smaller than they sounded.
The first was Kaamasjoki's neutral meter. Their younger transformer, which had stayed on the live line, had carried a peak of seventy-one amperes at ten to ten, and above forty for most of an hour. Vahti scaled it to Syväkoski's line, a little longer, with a different loop and a different bit of rock, and gave the result with all the caveats attached. "About eighty amperes in our neutral at the peak. About twenty-seven in each phase. Above twenty for perhaps fourteen minutes. That is past the maker's curve, but not far, and not for long. If you ask me whether it would have failed, I do not know. The curve is cautious. The unit may well have come through. I have found nothing that tells me which."
"So I shut the village off for nothing," said Anja, who had not slept.
"You shut the village off for a risk that was real and whose size neither of us can ever measure, because we cannot run the night again. The cost of it is on the record: two hours and forty-three minutes of dark, eleven houses that went below ten degrees indoors, one burst pipe in Hannele's cellar, which Veikko's boys have fixed, and a lot of people who cannot say whether they were rescued from anything. I will not tell you it was needed. I will tell you it was reasonable, and I would write it that way."
It was the first Sunday of the month, and she drove to Rovaniemi for the Mass. She sat at the back. At the intercessions she gave the names, Tadeusz first, and then, because there was room, the nine hundred and some of the Syväkoski graves, whom she did not know. She had thought it would feel like too many. It felt about right.
The second was the oil. Vahti had sent for an extra sample on Friday, on its own account, and it came back on Monday. It read nine parts per million, the same as September. The transformer, switched off, had not got worse. "It tells us nothing about the case where it was on," said Vahti, "and I will not pretend it does."
The co-operative met again on Tuesday and voted to order a new transformer, fourteen months away, with a neutral blocking device in it. It would cost the village most of two years' surplus, and Veikko, who chaired, said it in the kitchen out loud so that nobody could say later that it had been done quietly. The mobile unit was booked for the winter, as insurance, and Vahti put a line in its own log that it would ask for an extra oil sample after every storm from now on, whether or not anyone had heard a rasp.
By then the candles in the cemetery had burned out, except a few, and the jars stood in rows in the snow with their glass blackened at the top. It was Pirjo's job to collect them, and there was no electricity involved, and she had asked for helpers. Anja said she would come.
She stopped at the substation on the way, because it was on the way. The yard was empty. She stood by the fence with her hands in her pockets, as she had stood on the Saturday, and listened to the hum.