Chapter 3 Ghost Particle #2
Suddenly, Laurel is in Madison, Eli tracing a line on her arm.
Neutrino, he says. Little neutral one. Also known as ghost particles.
They can pass through rock, ice, whole planets without stopping.
Trillions stream through our bodies every second, like light through a window.
Famously difficult to catch, like any ghost, because they almost never interact with matter.
But when they do, they produce something we can measure: Heat.
Sound. Sparks. They’re born when the nuclei in separate atoms combine, or split apart.
“—and neither would ANITA, if they knew how to do their math. All right,” says the second man, to Laurel.
Ushered forward, she deposits the coffee at his elbow.
The man sips. “Fine.”
“Are you sure?” asks Laurel, eager for the chance to hear more.
“Positive,” he says, taking stock of her for the first time, and lowering his voice afterward.
Laurel suspects that ANITA refers to the next wave of experimenters, the particle physicists Jules described.
If word of their findings has reached other research teams on base, a presentation can’t be far behind.
Sure enough, when she checks the bulletin board, a new notice is tacked next to the Times article: ANITA—the Antarctic Impulsive Transient Antenna—will report their results on Sunday night.
—
The morning of the presentation brings Laurel’s first Antarctic storm. On the way to breakfast, she stops by the satellite feed. An iceberg the size of San Francisco is spinning like a clock.
In the galley, she joins Louis, Nita, and Charlie.
“Fifty-mile-per-hour winds,” Louis says. “I think we’ll be able to lean.”
Nita hesitates. “We’ll get in trouble.”
In Condition 1 weather—less than one hundred feet of visibility—work is canceled, and residents are only permitted to leave their dormitories for meals. Laurel can barely see the firefighters planting signposts outside.
Louis is watching the firefighters, too. “They’re still a ways off. If we go now, they won’t see us.”
They down their coffees, burrow into their coats. Louis leads them out of an emergency exit, his mittened hand in Laurel’s gloved one. The force of the air is astonishing. Laurel and Charlie cower.
“Face downwind!” Louis shouts. “Lie back! Nita, show them how!”
Nita tips, as in a trust fall, her arms extended toward the sky. Laurel gasps: the wind holds her up. With her feet obscured by blowing snow and her dark hair streaming forward, she seems to be levitating.
—
By seven thirty that night, the galley seems to contain almost everyone on station.
The stewards rush to set up a table for the speakers, make as much coffee as they do for breakfast, and let down the heavy blinds: outside, it’s light enough to be morning.
The IceCube scientists sit at a front table with their arms crossed.
Nita and Sam have saved a row of chairs in the back.
When Laurel, Louis, and Charlie arrive, still in their uniforms, Sam hands each of them a hot chocolate.
Two physicists—a man who looks to be in his fifties and a woman perhaps ten years younger—are toying with a projector at the front of the room.
They seem anxious as they open PowerPoint and dim the overhead lights.
When the audience falls silent, the man selects the first slide, which reads: Anomalous neutrino signal detected from Antarctic ice.
“As you’ve all been aware,” he says, “a highly unusual visual phenomenon was first identified eleven months ago, in January of 2016, fifteen miles north of the station.”
The woman clicks the remote, and two images of the Arc fill the screen. On the left, the pink version appears against a background of apricot light. On the right: the Arc at night, a ghostly bluish-green.
“An initial wave of investigation began in February and concluded in July. That team arrived with a hypothesis: that the anomaly resulted from the interaction between sunlight and the ice shelf. But all atmospheric and solar hypotheses failed to explain why it persisted during winter. If it were a refractive phenomenon, it should have disappeared with the sun,” she says.
“We deployed the ANITA instrument to assess the anomaly’s connection to neutrino activity. ”
The next slide shows the Standard Model of elementary particles.
“There are three types of neutrinos,” the man explains.
“All are left-handed—you can think of them as spinning to the left—and though particle physics predicts that they should have right-handed partners, as other elementary particles do, such partners have never been discovered. The reason for this asymmetry remains a mystery.”
“I thought you said this was going to be interesting,” Louis whines. Nita swats him before putting her hand back in the pocket of Sam’s sweatshirt.
“Most neutrino detectors are built deep inside the earth to drown out the noise of other particles: in mines, in tunnels, and—as at IceCube—in ice.” The woman nods at the IceCube scientists, who stiffly return the gesture.
“ANITA is different: an instrument, suspended by a balloon, that flies over the Southern Ocean. Our detector was designed to search for ultra-high-energy neutrinos. It measures the Askaryan effect, radio pulses emitted when these particles collide with ice.”
She looks at her partner, who nods a fraction of an inch, as if to encourage her to continue.
“Until now, neutrinos have only been detected flying toward the planet, from outer space. But two of our flights detected upward energy showers with angles so steep that we’ve concluded they came from one of two sources,” she says.
“The first possibility is that they originated from the earth itself—that they flew out of the planet, toward the sky.”
Uneasy chatter fills the galley. A man sitting near the IceCube table calls, “And you say these were high-energy neutrinos?”
“That’s right. Low-energy neutrinos pass through the planet all the time, but the Standard Model tells us that high-energy particles shouldn’t be able to travel more than a few hundred miles through solid matter.”
“I’d like to see how they determined those angles,” someone says, from deep within the recesses of a fur-lined parka.
“IceCube has never reported upgoing showers,” declares someone else.
“Exactly,” says the male physicist, stepping forward.
“IceCube is situated thousands of meters belowground. The fact that they haven’t had a similar detection suggests our second hypothesis is more accurate: that the particles came from somewhere near the surface of the earth—somewhere like the anomaly. ”
The conversation in the galley swells. Laurel catches fragments:
“There’s absolutely no way…”
“Would upend the Standard Model…”
“How do you explain the color?” asks a dogged-looking woman in the front row. “Neutrinos don’t interact with light.”
“No,” says the man, “but they do interact with atmospheric gases. The pink color could come from the excitement of oxygen molecules, the blue-green from oxygen and nitrogen.”
“What does this mean?” asks somebody else.
“We aren’t sure yet,” the female physicist says. “We’ve scheduled additional flights; we’re combing through a decade’s worth of data. What we know so far is that these signals can’t have come from any of the three neutrinos in the Standard Model.”
A black slide appears on the projector screen: A fourth neutrino? At the sight of it, one of the IceCube scientists shakes his head, but others remain fixed, their bodies canted toward the speaker.
“We’re considering the possibility of a new neutrino,” she continues. “Based on its trajectory—the fact that it travels in the opposite direction of the neutrinos we know—this fourth neutrino would have inverted properties.”
For a moment, there is silence. The woman seems even more unnerved by this than by the commotion that preceded it, and she pauses to collect herself.
“It would be right-handed, for example. And if this is the case—if it spins not to the left, but to the right—then it would also have an inverted arrow of time.”
“Well, that explains everything,” says Louis. But a vast contagious rumble is moving through the galley. Some of the remaining attendees are chattering in small groups; others have already begun to queue in front of the presenters.
“Did you hear what they said about the arrow of time?” asks Nita. “What does that mean?”
Charlie shrugs. “Beats me.”
But Laurel can feel her heartbeat in her ears. She has the sense that she is meant to be here, right now, rooted to the spot.
“Well, time moves forward, doesn’t it?” says Louis, yawning. “So if you reverse the arrow…”
“We go backward,” Laurel says.