Neutrinos continually shot straight through the earth from space. Sixty billion passed through a person’s fingertip every second. They were one of the fundamental particles of the universe, yet they remained a mystery to modern physics.
Belowground, the Super-Kamiokande detector sought to record and study those elusive passing particles. On rare occasions, a neutrino would collide with a molecule—in the detector’s case, a water molecule. The impact shattered the nucleus and emitted a blue cone of light. It took absolute darkness to detect that brief, infinitesimally small burst of light. To catch it, thirteen thousand photomultiplier tubes lined the massive water tank, peering into that pitch-black tank, ready to mark the passage of a neutrino.
Still, even with such a huge shielded facility, it was a challenge to find those particles. The number of neutrinos captured by the photomultipliers had held at a fairly steady pace over the course of the year—which was why the data on the monitor confounded him.
Jun stared at the graph on the screen. It displayed neutrino activity over the past half day.
He ran a finger across the screen, tracing the graph. His fingertip spiked up as it reached the three o’clock hour this morning. It marked a sudden and massive burst of neutrinos that occurred three hours ago, a level never recorded before.
It has to be a lab error. A glitch of some kind.
For the past three hours, the entire facility had been troubleshooting every piece of equipment and electronics. Next month, his team was scheduled for a joint experiment with CERN, a Swiss facility.
If that had to be canceled—
He stood up to stretch his aching back and crossed to his window. He loved the light at this early hour, perfect for photography, a hobby of his. Adorning his walls were pictures he’d taken of Mount Fuji at sunrise, reflecting in Lake Kawaguchi, another of the Nara Pagoda set against a backdrop of fiery maples, or his favorite, a picture of Shiraito Falls in winter, with skeletal ice-encased trees scattering the morning light into rainbows.
Beyond his window was the less picturesque landscape of the observatory campus, but a small water garden lay below, alongside a raked and swept Zen garden, swirling around a tall craggy rock. He often felt like that rock, standing alone, bent-backed, swirled by life around him.
Interrupting his reverie, the door swung open behind him. A leggy blond colleague, Dr. Janice Cooper, a postgraduate student from Stanford, strode swiftly into the room. She was thirty years younger than Jun, as thin as Jun was round. She always smelled of coconut oil and carried herself as if she were about to bound away, too full of California sunshine to sit still.
Sometimes her simple presence exhausted him.
“Dr. Yoshida!” she said, out of breath as if she had been running. “I just heard from the Sudbury Neutrino Observatory in Canada and from the IceCube facility in Antarctica. They’ve all recorded massive spikes of neutrinos at the same moment in time as we did.”
Clearly she wanted to say more, but Jun held up a hand, needing a moment to think, to let out a sigh of relief. So the data wasn’t a glitch. That solved one mystery—but on its tail rode another more disturbing question: What then was the source for such a colossal blast of neutrinos? The birth of a supernova deep in space? A massive solar flare?
As if reading his mind, Dr. Cooper spoke again. “Riku asked if you’d join him down below. He believes he knows a way to pinpoint the source of the neutrino surge. He was still working on that when I left.”
Jun didn’t have time for the eccentricities of Dr. Riku Tanaka. With clear proof that the spike in neutrinos was not the result of a fault in their systems, he felt the mystery could wait a few hours. He’d been up all night, and at sixty-three years of age, he was no young man.
“He was insistent,” Dr. Cooper pressed. “Said it was important.”
“Everything’s important with Dr. Tanaka,” he mumbled under his breath, not bothering to hide his disdain.
Still, a bit of excitement entered Dr. Cooper’s voice. “Riku believes the neutrinos might be geoneutrinos.”
He looked sharply at her. “That’s impossible.”
Most neutrinos came from the background radiation of the universe: from solar flares, from dying stars, from collapsing galaxies. But some neutrinos—called geoneutrinos—originated from the earth itself: from decaying isotopes in the ground, from cosmic rays striking the upper atmosphere, even from the explosion of atomic bombs.
“That’s what Riku believes,” she insisted.
“Nonsense. It would take the equivalent of a hundred hydrogen bombs to generate a neutrino blast of this magnitude.”
Jun crossed toward the door, moving too suddenly. Pain jolted up his right leg, a flare of sciatica.