The Retired Professor's Story

An old notebook bore a name — Zheng Boyuan, a retired physics professor, written on the same day as Su Wan's paint pigment formula. Three hours later, the off-road vehicle raced off the national highway and turned onto an unlit dirt road. The wheels crushed gravel, which rattled against the chassis like fine drumbeats.

When the off-road vehicle stopped at the gate of a suburban compound, the sky was completely dark.

Jiang Fei pulled the handbrake with her uninjured hand and turned off the engine. The moment the headlights died, the surrounding darkness surged in like a tide. There were no streetlights in the suburbs — only the dim yellow glow from a few distant windows. Jiang Fei leaned back in her seat, eyes closed, catching her breath. Her left arm was wrapped in a torn T-shirt; the blood had already clotted into a deep brown.

Lin Shen looked at her, wanting to say something. Jiang Fei didn't open her eyes. "Stop looking at me. Knock on the door."

Lin Shen pushed open the car door. The suburban night wind carried the smell of soil and grass — different from the city. He walked to the courtyard gate. The iron gate was rusted, the house number faded until it was nearly illegible. He checked the note tucked inside Su Wan's diary — the address matched.

He knocked. Three times. The rhythm of a pencil tapping a desk.

No response.

He knocked three more times, harder this time.

Slow footsteps came from the courtyard — dragging and hesitant. The small window on the iron gate slid open, revealing an old man's face. Salt-and-pepper eyebrows, eyes set deep in their sockets like two pebbles washed by water for a long time. The old man studied him for a moment, then glanced at the off-road vehicle parked outside and at Jiang Fei leaning against the car door, smoking.

"Who are you looking for?" The voice was dry, as if he hadn't spoken to anyone in a long time.

"Professor Zheng Boyuan," Lin Shen said. "Su Wan gave me this address."

Three seconds of silence from the small window. The old man's fingers trembled slightly on the window's edge — not from fear, but from Parkinson's. He stared at Lin Shen for a moment, then pulled open the iron gate.

"Come in."

A persimmon tree grew in the courtyard. Two old rattan chairs sat beneath it. The main room door was open, lit by a single forty-watt incandescent bulb — dim light. The old man led them inside and gestured to the sofa. The sofa cover was floral fabric from the 1980s, washed pale. On the tea table sat an enamel cup with chips missing from the rim, steeping strong tea.

Jiang Fei followed her in, leaning against the doorframe without sitting down. She scanned the room — bookshelves covered the entire wall, physics journals stacked crookedly, some open with dense red-ink annotations. In the corner sat an old oscilloscope, dusty but still plugged in.

Old Zheng sat down in the rattan chair, hands trembling on his knees. He looked at Lin Shen, then at Jiang Fei.

"Su Wan." He repeated the name, as if chewing on something long forgotten. "That girl — is she still alive?"

Something squeezed Lin Shen's heart.

"You know her."

Old Zheng didn't answer directly. He picked up the enamel cup, took a sip of tea, the rim clinking softly against his teeth. "She came to see me. First time was a year and a half ago. Second time was three months ago."

"What did she come for?"

"To ask about the same thing." Old Zheng put down the cup. "She asked if the Mirror Project could be shut down."

The room fell silent. A moth fluttered against the incandescent bulb, its wings making faint rustling sounds. Lin Shen's hands unconsciously tightened, his knuckles turning white.

"What is the Mirror Project?"

Old Zheng raised his eyes to look at him. In those eyes, weathered by more than sixty years, there was something very complex — pity, caution, and something deeper, like guilt.

"Young man, tell me first — where is she now?"

"Gone," Lin Shen said. The word scraped his throat like sandpaper. "No one in the world remembers her. Only me."

Old Zheng was silent for a long time. His hands trembled more violently, the cup tapping lightly against the saucer.

"Four years," he finally said, his voice even quieter. "I haven't mentioned this to anyone in four years."

He stood up, walked to the desk, and pulled open the bottom drawer. Inside was a stack of yellowed lab notebooks, their covers stamped with a now-defunct research institute logo. He pulled one out and opened it — it was filled with handwritten calculations and diagrams. Some pages had been torn out, leaving jagged edges.

"The Mirror Project. Full name — Parallel Reality Mirror Imaging Research Project. Launched fourteen years ago. I was in the third batch of researchers."

Lin Shen's breath stalled for a beat.

"Fourteen years ago, a group of quantum physicists discovered a phenomenon — under specific energy conditions, two parallel realities could produce a brief resonance band. Simply put, two worlds could 'touch' each other." Old Zheng flipped through the notebook, the pages rustling under his trembling fingers. "At first, no one took it seriously. Parallel worlds — that's science fiction. But the experiment in '03 shut everyone up."

"What experiment?"

"The first cross-reality connection." Old Zheng's voice grew very soft. "It lasted only 0.3 seconds. One researcher's violin disappeared from this world for 0.3 seconds. When it came back, there was a scratch on it. The string temperature had risen by 0.5 degrees — it had been to a world slightly colder than ours, and then it came back."

Jiang Fei exhaled smoke at the doorway. She spoke for the first time: "What can 0.3 seconds prove?"

Old Zheng turned to look at her. "0.3 seconds is more than enough time for a dog to cross a room."

Jiang Fei said nothing more.

"The project grew bigger. Funding was approved. The lab was expanded. Equipment was upgraded. In ten years, we conducted no fewer than two hundred experiments." Old Zheng's voice grew heavier. "But the real breakthrough came ten years ago — we successfully maintained a stable passage for a full forty-seven seconds."

"Passage," Lin Shen repeated the word.

"The membrane between two worlds — torn open by energy." Old Zheng said. "Forty-seven seconds. Enough time for a person to walk in and walk back out."

A chill ran down Lin Shen's spine.

"Someone went in."

Old Zheng was silent. The moth finally tired itself out, landing on the lampshade, motionless. Only the sound of three people breathing remained in the room.

"Lu Yan's wife," Old Zheng said.

The name hung in the air like a nail.

Lin Shen remembered Lu Yan's frozen eyes. "Then what?"

"Then the passage collapsed."

Old Zheng's voice suddenly became very light, as if he were speaking of something he didn't want to recall in his lifetime.

"It wasn't a normal shutdown. It was a cave-in. The energy fields of the two worlds lost balance, and the passage snapped in the middle. Lu Yan's wife —" He paused, his hands trembling more violently. "She was inside the passage at that moment. When it broke, she was caught between the two worlds. Not entering the other world. Not coming back. Stuck in between. Completely annihilated."

No one spoke in the room. Jiang Fei stubbed out her cigarette on the doorframe, leaving a black mark.

"Lu Yan saw the whole thing," Old Zheng said. "He stood in front of the control panel and watched his wife's body split apart from the middle — not physically splitting apart, but splitting apart in terms of existence. She was still standing there, but she wasn't that person anymore. Her outline was still there, but the inside was empty. In less than a second, even the outline was gone. Like a drop of ink falling into the ocean — at first you can still see the color, then it disperses, and there's nothing."

Lin Shen's back pressed hard against the sofa. He thought of Su Wan. Su Wan's face. Su Wan's voice. The toothpaste he squeezed for her every morning. If those things truly disappeared completely — not just death, but never having existed at all —

He dared not think further.

"After the accident, the project was shut down," Old Zheng said, closing the notebook. "But Lu Yan didn't stop. He gathered a group of people in his own name and founded the 'Correctors.' He told us that the earlier experiments had made a fundamental mistake — we thought the two worlds could coexist, but in reality, every contact left tiny cracks on the membrane. When these cracks accumulated to a certain point, it would collapse — just like that time."

"So he started erasing the trespassers," Jiang Fei said.

"Right." Old Zheng looked at her. "Lu Yan's logic was — everyone who came from the other world isn't an 'existence,' but a 'mistake.' Their very existence is a threat to both worlds. Correcting them isn't killing — it's correcting an error. Like using an eraser to erase a wrong word."

"He's insane," Jiang Fei said.

Old Zheng didn't argue. He lowered his head, his fingers tracing circles on the cover of the notebook.

"When I left the Correctors, Lu Yan told me — you can choose not to do it, but don't stand in my way."

"Why did you leave?"

Old Zheng raised his head and looked at Lin Shen. What was in his eyes was clearer now — it was guilt. Deep, decade-old guilt.

"Because after we did that experiment with the dog, we should have stopped," he said. "A dog can't talk. But a person can. We recruited a volunteer for the second live experiment — that person was Lu Yan's wife. She volunteered. She was the first living person to walk into the mirror world, and the only one who never came back. From the day she died, I knew this experiment shouldn't continue. But I said nothing."

He paused, his voice even lower.

"When Su Wan came to see me, I told her the truth. I said, I can give you the passage coordinates and the key. But you also need to be prepared — you might never return."

"What did she say?" Lin Shen asked.

Old Zheng looked at Lin Shen, a new layer appearing in his eyes.

"She said — it's okay. I just want to confirm one thing."

"What thing?"

"She said — I want to confirm whether anyone actually cares about me," Old Zheng finished, then fell silent.

Lin Shen dug his fingers into his palm.

Outside, the wind picked up. The persimmon tree rustled. The incandescent bulb flickered.

Jiang Fei suddenly straightened up. She tilted her head, her ear turned toward the direction of the gate.

"A car," she said. Her voice was low, but hard.

All three stopped to listen. From the distant dirt road came the faint sound of engines. Not one — two.

Old Zheng stood up. His hands stopped trembling. He walked to the window, pulled back the curtain to look, and when he turned back, his expression had changed — from guilt to something else. As if a decision had been made.

"Lu Yan's men. Faster than I expected."

"Is there a back door?" Jiang Fei asked.

"Yes. There's a cellar entrance behind the kitchen, leading to the drainage ditch in the backyard. Go that way."

"What about you?"

Old Zheng didn't answer. He walked to the bookshelf, pulled a folded piece of paper from the spine of an *Introduction to Quantum Mechanics* book, and pressed it into Lin Shen's hand.

"Passage coordinates," he said. "Yingzuiya Hydropower Station, basement level three, the original backup control room. The equipment should still be there. As for the key —" He pointed to the paper in Lin Shen's hand. "It's written on there."

Lin Shen unfolded the paper. On it was a combination of numbers and symbols, with a simple map drawn beside them.

"Come with us."

"If I leave, they'll search," Old Zheng said. "They'll search here and find traces of you. Then they'll find the hydropower station. But if I stay and talk to them, I can buy you at least twenty minutes."

Jiang Fei was already at the kitchen entrance, pulling up the old carpet on the floor. Beneath it was a wooden door.

"Go," she said.

Lin Shen stood still, looking at Old Zheng.

"Lu Yan is insane," Old Zheng suddenly said, his voice carrying something very heavy. "He's not maintaining order. He's atoning for his sins. But his way of atoning is to make everyone like his wife die once more. He thinks erasing them can erase the guilt in his heart. But he's wrong."

The engines grew closer. Headlights swept over the courtyard wall, casting shifting shadows on the windows.

"Go," Old Zheng said.

Jiang Fei had already opened the cellar entrance. A damp, earthy smell rose up. She looked back at Lin Shen.

Lin Shen held the paper, looking at Old Zheng.

Old Zheng smiled at him. The smile was strained, but genuine.

"Young man. Some things are harder to forget than to remember. You need to remember her."

The engines stopped. The sound of boots crunching on gravel came from outside the iron gate.

Lin Shen took a deep breath — the same way he did every time before entering his home. Then he turned and followed Jiang Fei into the cellar opening.

Just as the wooden door closed, he heard Old Zheng pull open the front door, and the words he would never forget for the rest of his life —

"You're here. I've been waiting for you. Care for some tea?"