Chapter 6: The Probability Wasn’t Zero
Qiao Zhiyi opened her eyes to an equation.
It covered three quarters of the board in white chalk, beginning with a probability density function and ending in a conditional expectation she should have been able to solve without writing it down.
She stared at it blankly for a second, expecting it to change. But it didn’t.
The symbols were familiar, the room was almost familiar.
Looking around like she had never seen it before, she catalogued everything, trying to place it.
There were tiered rows of polished desks descended toward the front of the lecture hall. Afternoon sunlight crossed the floor through six narrow windows, broken at regular intervals by the shadows of students. An air-conditioning vent hummed overhead. Someone behind her tapped a pen against a tablet in an uneven sequence.
Three taps.
Pause.
Two taps.
Pause.
Three taps.
A man stood beside the board with a piece of chalk held between two fingers.
He was staring at her. In fact, everyone was staring at her.
Zhiyi lowered her eyes and saw that her hands were resting on an open textbook.
The pages were clean. White. Unstained by water, smoke or blood. A mechanical pencil lay precisely parallel to the book’s spine. Her left thumb held her place beside a completed line of calculations written in handwriting she recognized as her own.
Her fingers were uninjured.
The four crescent-shaped cuts in her palm were gone.
Zhiyi turned her hand over.
Smooth skin. Short, clean nails. No calluses from pulling carts or reinforcing shelter doors. No scar across the base of her thumb from the sheet metal that had sliced through her glove during the freeze.
Her wrist was thin. Too thin. Even after being starved for so long, they weren’t this thin. The sleeve covering it was dark blue, trimmed with the silver insignia of Jingyuan Private University.
Zhiyi stopped breathing and forced herself to blink.
When she looked again, the lecture hall remained around her.
The air conditioner continued humming.
The student behind her tapped his pen three more times.
But... how?
The last thing that she remembered was that Pei Hanchuan’s arms had been around her.
His shirt had been wet with sweat. His heartbeat had slowed beneath her ear until the pauses between beats became longer than the beats themselves.
He had promised her a house beside a lake.
He had told her to find him.
Then she had died.
Her heart struck the inside of her chest.
Once.
Twice.
It was too fast.
She pressed two fingers against the pulse in her throat. The rhythm was strong and regular despite the sudden increase. Her lungs expanded without pain. The air entering them was cool enough that she could feel it moving through her nose and down her throat.
She was breathing.
That was inconsistent with death.
Cardiac activity didn’t resume without intervention after prolonged oxygen deprivation and heat-related organ failure. Even if it had, the resulting neurological damage would be significant. It couldn’t restore lost tissue, reverse years of ageing or place her inside a university classroom she hadn’t seen in more than ten years.
Therefore, she hadn’t survived.
She had been reborn.
Zhiyi’s mind went silent.
The conclusion remained in front of her, complete but unusable.
Rebirth required consciousness to continue after biological death. It required that consciousness to move backward through time without degradation, then occupy an earlier version of the same body while retaining memories accumulated during a timeline that no longer existed.
There was no accepted mechanism for any part of that process.
No controlled evidence.
No reproducible data.
No way to calculate the probability because there was no reliable sample size.
But there was one confirmed occurrence existed.
Hers.
Therefore, the probability was no longer zero.
But that didn’t make it measurable.
"Miss Qiao?"
The man beside the board spoke and Zhiyi looked at him.
Professor Han.
She remembered his name after 1.7 seconds.
He had taught Advanced Mathematical Modelling and Probability Theory during the last year of her undergraduate program. He preferred handwritten proofs, disliked calculators and added unnecessary biographical details to examination questions.
He had also asked her something, but Zhiyi didn’t know what it was.
Professor Han’s eyebrows drew together. "Are you feeling unwell?"
That wasn’t the original question.
His chalk remained raised toward the equation, suggesting he had asked her to complete the proof or identify an error. The students seated between them looked from the board to Zhiyi with varying degrees of interest.
Ordinarily, not knowing the question would have been unacceptable.
A question left unanswered remained open.
It waited.
It demanded completion.
But right now, Zhiyi didn’t care. For the first time she could remember, and she could remember everything, she didn’t care.
She reached beneath the desk and removed her phone from the side pocket of her bag.
The device recognized her fingerprint.
There were no cracks across the screen. The battery was at eighty-two percent. Four unread messages waited beneath a weather notification, and a red circle containing the number nine sat above her email application.
Zhiyi ignored all of them.
She opened the search engine.
Her fingers hovered above the keyboard.
Pei Hanchuan.
Two words.
One name she had never typed into a search bar before the world ended.
Hanchuan had told her about the company he once owned. He had mentioned buildings and board meetings as if they belonged to someone else. By the time Zhiyi met him, business records had become fuel, banknotes had become insulation and the tallest remaining corporate towers were either flooded or frozen.
She typed his name.
Professor Han said something else, but Zhiyi shook her head without looking up.
She didn’t know whether the gesture meant she wasn’t ill, she couldn’t answer, or he needed to stop speaking to her.
It didn’t matter.
The results of her search had loaded.