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City of Choice

Translated by Ken Liu

Published onOct 26, 2023
City of Choice

The floodwaters surged everywhere, turning mountains into islets and submerging hills. The people were terrified.

— From Records of the Grand Historian, Annals of Xia, by Sima Qian

Translator’s note: The above quote is taken from Sima Qian’s account of the legendary deeds of Yu (the founder of the Xia Dynasty), and Gun (Yu’s father). As Yu’s story is thematically important for “City of Choice,” I’ll briefly recount it here. During the time of the Great Flood, when the people were overwhelmed by the deluge, Gun was put in charge of solving the problem. For nine years he led the people in building dikes and barriers, but the flood showed no signs of abating. Yu then succeeded him. Instead of merely building walls against the surging waters, Yu shifted to a strategy of digging channels to divert the floodwater into lakes and seas. After thirteen years of tireless toil, Yu saved the people from the Great Flood. Da Yu (Great Yu) then became one of the most important heroes of Chinese culture, and his story is among the first that young children learn. Several other names in this story also make reference to the legend of Da Yu, but I’ll leave any follow-up research to the interested reader.

“Yu” is a homonym for a Chinese word meaning “rain.”

“Gun” is a homonym for a Chinese word meaning “get lost.”


The rain grew heavier.

Windshield wipers turned the scenery outside into flickering frames of Impressionist paintings. Glowing taillights and neon signs along the road melted, turning into blooming specks of paint on a dark stage curtain. Fingers gripped tight around the doorhandle, I stared at the wild waves dashing against the sidewalk trees.

“Are you sure you want to get off here?” Fei Boyi asked me.

None of the other four in the van said anything. The study had to go on.

The only reason we were here in the city on a weekday in the middle of a storm was because Fei’s “Safe City” project had just delivered an update to the client (a public-private civic partnership). While discussing Yu, the emergency survival navigation system, the client representative suddenly asked, almost casually, “Do I have it right that all your trials were conducted during the dry season?”

Fei, always quick on his feet, said, “We have been in the field when it rained, too.”

“I doubt you’ve tested the system during flood season, though. I think you’re all working remotely these days, no?” The client representative squinted thoughtfully. “I want to be sure that the flood escape routes computed by Yu are usable in real life. The system needs to save lives in an emergency; we can’t afford to cut any corners.”

She was right. Very few developers ever tested their AI-enhanced products in extreme situations, but Yu was specifically intended as an emergency-response system, when everything that could go wrong did. After all, it wasn’t for nothing that the city was named Ze.1

So, after that, as soon as meteorologists issued a red alert for floods during the next storm, Fei Boyi spent a whole afternoon on the phone, summoning every core member of the project team to come into the city for a field study. As it was the first time Yu was fully operational, he wanted all of us to be on-site to test the system.

I had parked near Fei Boyi’s company to meet up with the rest of the team; the parking lot was at a slightly higher elevation. “I need to get out early,” I said to Fei. “My daughter is alone at home. If I don’t leave now, I’ll be stuck in traffic.”

The van drove through a dip in the road, and turbid floodwater surged up the hood onto the windshield. The inside of the van was eerily silent, amplifying every strike by debris against the body of the van into a terrifying clang.

“Are you sure you want to continue to the next site? Please be careful. Safety first,” I said.

“Will you be all right, leaving by yourself?” he asked.

“I’m sure I’ll be fine,” I said. “I have Yu installed in my car.”

Someone from the backseat scoffed. “That’s a terrifying thought.”

I pretended to not hear it. Fei Boyi wasn’t my boss. I was collaborating with his team because back when he was bidding for the project, he thought he would have a better chance if he added an urban safety planner. Once we started working together, however, we realized that our approaches were nearly incompatible. While he thought I knew “literally nothing” about artificial intelligence, such that my technical suggestions were “useless,” I couldn’t accept his singular focus on goal-oriented optimizations, paying no heed to issues of equity. In the end, the nominal “collaboration” resulted in very little: the only traces of myself left in Yu were the data integration work I did for the emergency shelters and city building plans.

I was never really going to put my own life in the hands of Yu; my answer to Fei was just an attempt to be polite. I knew the roads well, and I was sure I could drive home safely on the elevated highway.

“All right,” he said, giving up on trying to convince me. The van door slid open. “Drive carefully.”

“You too.”

Wading through the waist-deep water, I finally found the steps leading up to the parking lot, still unflooded. As raindrops slammed against me, I checked my car’s external flotation airbags. As soon as the car detected the tires’ loss of grip in deep water, the airbags would inflate and turn the car into a small raft. The airbags could deploy only once, so afterwards I’d have to take the car into the shop to get new ones installed.

The process was a hassle, but the airbags really did save lives. I had them installed for the first time three years ago, during the flood season. At the time, my residential district offered free flotation-bag installations to all pregnant women, and I took advantage of the offer, thinking, “Why not? Free is free.” However, on the day of my delivery, there was an unprecedented storm, and I had to float my way to the hospital on the airbags.

After Ah Qi’s birth, the weather degraded even further. As soon as June rolled around, there seemed no end to the rain. I had to deploy the airbags several times to get to my destination safely. Having seen what they could do, I never hesitated to pay for the reinstallation. Later, after we moved to the suburbs, things got better. I could go from my home to city center by taking only elevated highways, and that meant fewer instances where I needed the airbags.

Let’s hope my good luck continues today, I thought to myself.

As soon as I was strapped into the driver’s seat, a Y-shaped glow flashed over the windshield. “Welcome back, Ms. Tushan Jiao. Yu is at your service.” The synthetic voice sounded like a young girl, high-pitched and crisp. “My name is Xiao Yu. Let me help you get to your destination.”

“Xiao Yu?” I looked at the windshield, blurred by the thick rain, rather amused. That’s what happens when you name your system with a homonym for “rain.” “I wouldn’t call what we have now a ‘little rain.’ ‘Da Yu’ would be more appropriate,” I muttered.

“Due to the ongoing red storm alert, you cannot shut off Yu.” Somehow the software agent heard me! But it obviously didn’t understand my attempt at a joke, as it switched to a young male voice.

“Gun,” I said, trying to summon the older, more familiar navigation software, “get me home.”

“Please refrain from hostile language,” the synthesized voice said. “Maintaining a state of equanimity can help you reach your destination safely. I’ve already analyzed your historical navigational data. I will assist you in getting home.”

Apparently the system thought I had said “gun!” get lost, instead of just naming its predecessor. “Look, I was trying to summon the old navigation software—”

A clap of thunder cut off this pointless debate. The HUD showed that the level of risk associated with the route computed by Yu was increasing with each passing second. “We should depart immediately,” it said. “Flood peak will reach this location in approximately seven minutes. I’ve taken note of your external airbags, for which choice I commend you. Please take the southern exit of the parking lot.”

“That doesn’t make sense,” I said. “I’m trying to get on the elevated highway.” The southern exit led me away from the highway.

“I will bring you to the highway,” it said. “However, I must make accommodations for special circumstances right now. Please depart immediately.”

I floored the gas. The boom bar at the parking lot exit was high in the air; all automated parking lot systems were designed to stay open as long as a red storm alert was in effect. The exit led to a downslope, and as soon as the front of my car plunged into the floodwater, the gasbags deployed, and I felt the car float. Today was evidently my lucky day.

The droning from the back of the car told me that the propellers had taken over from the wheels. Yu used the HUD on the windshield to show me augmented-reality outlines of flooded roads and underwater obstacles. I was impressed; this part, at least, clearly represented an upgrade from Gun.

However, the route it had computed for me was very odd: It was directing me to sail over several “barriers”—actually a group of low buildings.

Since I had never taken the route out of the southern exit, I had no choice but to follow Yu’s guidance. “I don’t like this,” I said. “You’re taking me farther from the elevated highway.”

“It will take only a few minutes,” it said. “We need to rescue a couple of kids.”

Another peal of thunder cracked over my head. A tree fell behind me, and the resulting waves inundated my car, turning the makeshift raft into a submarine for a moment. My car deployed its snorkel in response.

“You are taking me on a rescue mission instead of home!?” I was close to shouting by this point. “I’m not a trained first-responder!”

“But you’re the closest.”

Now I really did want to show Yu some “hostile language.”


“The problem isn’t that you found those two kids.” Fei Boyi’s face was so swollen that I had a hard time telling his lips apart from his eyes. Talking was clearly difficult for him, but he wouldn’t stop the conversation.

I shut off the video feed so I didn’t have to see his suffering. “I don’t understand. Isn’t it good that we rescued people? What are you so worried about?”

“The problem is … there were two other people in that house, beyond those two kids.” Very deliberately, he asked, “Are you absolutely certain that Yu never mentioned them?”

“I’m sure.”

“Yet Yu knew they were there. That is the problem.”

“But maybe Yu just didn’t access that … oh what do you call it … that layer, that data layer,” I said. “It likely planned the rescue solely based on the surveillance camera footage, without cross-referencing the residential record for the building itself. It saw there were two children on the roof still alive and concluded that they needed to be rescued. Simple.”

Fei Boyi was silent for some time. “I suppose that’s good enough.”

“Good enough?”

“Listen,” he said, his voice insistent, “we must be consistent in our answers. No matter who asks later, this is the answer we’ll both give. Yu concluded that there were people on the roof needing rescue based on infrared surveillance camera data. Got it?”

“What else could the answer be?” I asked. “How else could it have decided what to do?”

“I have no idea.” Fei sounded exhausted and helpless. “Yu’s algorithm is a black box.”


The fear-tinged confusion and anger from the puzzling call with Fei Boyi diluted my joy after a successful rescue, and I began to view Yu with more suspicion.

Going over the timeline, I realized that around the time Fei’s van was struck by that tumbling billboard, Yu was helping me launch my anchor into the stone pillar next to the flooded house. I knew that the external airbags came with such a piece of equipment, but I had never used it myself. The tip of the anchor resembled octopus tentacles, and once attached, it automatically secured the line in place.

As the storm raged, images of two girls appeared through the blurred windshield. The older was a teen, while the younger was not much older than Ah Qi. They clung to each other in a tight clump, and only the trembling of their stiff bodies showed that they were still alive.

Seeing my approach, the taller girl stood up and waved at me frantically.

I opened the door and shouted through the blinding rain, “You have to swim over! I need to hold the car steady.”

Just before the arrival of the flood peak, the water typically turned extra-turbid. I could feel the strengthening current, jammed with floating debris, pulling at the car. The propellers, straining against the draw, would not hold my position much longer. The older girl, tall and thin, pulled the life vests from the line near the anchor. She helped the younger girl put on one of the vests and began inflating it—I had seen this done during the safety equipment demonstration on airplanes countless times but never got to do it for real. Soon, the older girl put on her own vest and secured the younger girl as well as herself to the anchor cable. Hugging the little girl to herself securely with one arm, she jumped into the water. Then she fought with all her strength through the water until she grabbed onto one of the handles protruding from the external airbags. But no matter how much she strained, she couldn’t climb over the bags into the car, and a fresh wave tossed both girls back into the water. The younger girl drifted with a current for a couple of meters, but the safety line that secured her to the anchor cable held.

“Get yourself in first! Now!” I shouted at the older girl. She hesitated for a moment before grabbing the handle over the airbags with both hands and pulling herself up, sliding inside the car like a fish.

“Once you are securely inside the car, you may use the winch to help others,” said Yu in a calm voice. It projected diagrams and instructions onto the windows. Understanding what she needed to do, the older girl went to the winch at the door and worked hard until she fished in the younger girl, who had already swallowed a few mouthfuls of water.

At that moment, the roof on which the girls had been waiting vanished under the rising flood, appearing on the HUD as another “underwater obstacle.” I broke off the anchor, closed the door, turned the car around, and floored it again, heading for the elevated highway under Yu’s direction.

Crowded into the backseat, the two girls deflated their life vests. At first, they tried to remain calm, even after the younger one threw up all over the floor. Only after the tires on my car had struck dry ground again and the propellers had shut off did the older girl begin to cry.

“Please try to remain calm,” said Yu, “which will help everyone through this state of emergency—”

“Shut up,” I said.

The software did as I asked. The interior of the car was filled with quiet sobs from the two girls. Although I refrained from turning around, I could feel someone wiping her nose on the fabric on the back of my seat. Now that the worst was over, I could hear the pounding of my heart and feel cold sweat beading all over me. The traffic became jammed after about ten kilometers or so. Through the rain I could see that the highway was packed with cars that had deployed their bulky external gasbags, all resembling women trying to wade through the water by lifting the hems of their dresses. Even though we were bumping into each other, no one was in the mood to get out and start an argument.

After inching along for half an hour, I finally reached the spiraling exit that led towards home: the cluster of fortress-like towers that made me feel safe. I entered the parking garage, located on the seventh floor, through an aerial passageway.

These “integrated compounds” were all the rage among developers. In fact, as an urban safety planner, I contributed to their design. The compounds were usually located on elevated sites, and the buildings making up each compound, comprising five or six towers, were connected together by aerial walkways. In addition to residential units, the compounds also provided other services, such as education, healthcare, and dining.

The garage was located in the “support facilities building” at the center of the compound. This was the key feature that distinguished integrated compounds from traditional residential neighborhoods and districts. The lower levels of a support facilities building typically contained vegetable gardens lit by banks of powerful LED lights; the middle levels housed garages and workshops; and the highest levels held power plants, water treatment plants, gas and heating distribution equipment, and similar machinery. Our support facilities building, in particular, was the energy center for the entire suburban district. A small tokamak fusion reactor, occupying the tenth through fifteenth floors, provided all the energy needed for about a hundred nearby integrated compounds.

“You’ve arrived at your destination: home,” Yu said. “Thank you for using Da Yu.” Then it shut off the engine. I guessed that earlier, when I was talking about the heavy rain, it had assumed that “Da Yu” was my new name for it.

Da Yu … The Great Yu, the legendary hero? Not a bad name for something to help you escape from a flood.

The tires clicked into the floor conveyor belt, which would take the car to the repair shop. I took out my phone and selected “detailing” and “installation of new external airbags” as service options for the robots at the shop. As the kids climbed out of the car, I asked, “Everyone doing okay?”

The younger girl, still plump like a baby, managed to climb out by herself. Wrinkling her nose, she said, “What’s that smell?”

Her question reminded me of Ah Qi. Picking her up, I explained that the odor came from the sewage and greywater of the residential units in the compound, which would be processed and treated before being used to irrigate the vegetables in the levels below us. She wasn’t in the mood for an educational talk, however, and started to cry again. Luckily, the odor dissipated as soon as we entered one of the aerial walkways.

Following the gazes of the two girls, I looked outside the transparent walls of the walkway. The rain had deposited a pink haze over the evening clouds, and double rainbows framed the last dark wisps near the horizon. Below us, churning brown water made terrifying waves against the pillars that, like stilts, lifted all the buildings out of the flood.

Have you lost your family?

I couldn’t bring myself to ask the question, even as I tried to find the answer in their expressions.

“Let’s get going,” I said.

Once we reached my residential tower, we went to the daycare at the top of the building to pick up Ah Qi. Although initially surprised by the two girls who followed me, she quickly accepted the idea that “Mom rescued two kids” and seemed rather proud of me. As soon as we got home, she shared her treats with the two girls and distributed her own towels for their use. She didn’t even ask me about dinner, even though I knew she must be hungry.

I gave her a grateful glance, but I had to contact the police first and make a report about the children. I put on my headset and started a video call.

“Are you Tushan Jiao?” The policeman asked right away.

Startled, I stammered. “Yes. Um, I … I—”

“We’ve been looking for you,” he interrupted. “We couldn’t find you on the van.”

It took me a few moments to understand what he meant. “The rain was too heavy. I got off early so that I could take my own car home and take care of my daughter.”

“You’re lucky,” the policeman said with little emotion. “A billboard fell and crashed into the van. We rescued only one passenger, and the others are still missing. Can you identify him?”

He sent over a photograph. Blood-soaked bandages everywhere. “Fei Boyi,” I said. In the photograph I could also see one of his mud-covered arms twisted to the side, like a floppy worm. I could only imagine how much pain he was in.

“His condition is stable,” the policeman said. “Are you calling to make a report because you couldn’t get in touch with him?”

“No. I’m calling about two kids I saved on the way home.” I turned and made sure my AR glasses framed their faces for the recognition software. “Can you find their family?”

“Their names are Dan Zhu and Shang Jun,” the policeman said. “We can’t seem to get in touch with their guardians right now. As soon as we have more information, we’ll contact you.”

“Thank you.”


As soon as I hung up, I had a premonition that the two kids would be living with us for an extended period.

The flooding lasted three weeks, and we felt trapped in a warzone. With the number of mouths to feed in the household suddenly doubled, we ran low on food very quickly. I tried several times to get more food during the supply distributions, but since our area wasn’t nearly as hard-hit by the disaster as downtown, we got little attention. In the end, I was forced to join the homeowners committee, and, together with my neighbors, threatened nearby buildings with cutting off their energy supply in order to get them to share their water and food with us.

Eventually, after the floodwater receded, I set up bunkbeds in the living room for Dan Zhu and Shang Jun. I found out that ten years as well as a generation divided the two girls. Dan Zhu’s older sister, who was also Shang Jun’s mother, had disappeared during last year’s flood season, and the flood we had just endured had taken away Dan Zhu’s parents, turning both into orphans.

These successive catastrophes couldn’t blunt young Shang Jun’s naturally optimistic and open personality. Soon, the four-year-old seemed to put the painful past behind her and live for the future. Following Ah Qi’s example, she soon began to call me “Mama.”

For Dan Zhu, on the other hand, a life full of losses seemed to have left wounds that would never heal. Time and again, she would awaken in the middle of the night and stare out the window like an ethereal ghost. I dared not disturb her, and so the two of us reached a strange kind of nightly understanding: I knew that she stood there, and she knew that I knew she stood there.

Finally, one night, as I got up to get a drink of water, the ceiling light came on automatically and broke our mutual silence. I handed a glass of milk to her. Dan Zhu turned around, and I saw her eyes were red.

“What happened?” That was all I asked.

She broke down, falling into my arms. The glass of milk tumbled from her hand, breaking apart on the gray ceramic floor tiles, spilling white liquid everywhere. It took me a while to parse her words from the soul-wrecking sobs. “I knew they were below us … I knew … But all I wanted was to get out, to be rescued. I never … never begged you to go save them …”

She was talking about her parents.

“It’s not your fault.” I spoke deliberately, trying hard not to hurt her more with a careless word. “At the time, there was no way for me to rescue them. There was nothing you could have done.”

She nodded, then shook her head, wiping her tears on my pajamas.

Soon after, Dan Zhu got a scholarship to a boarding school in Yan2 City, and she moved away, refusing to return to Ze City.

But I couldn’t just forget about her. A few years later, I looked for opportunities to join Yan City’s urban renewal planning so that I would be able to travel there on business. As a result of overdevelopment, at one time Yan City had tens of thousands of units of excess housing, a virtual ghost town. Now, as a result of its two historical universities and an elevation about a hundred meters above Ze City, Yan City had become a hotspot, attracting new investment and residents migrating from the flooded coast. We redeveloped the empty residential towers into integrated compounds, endowing each cluster with its own basic infrastructure, manufacturing, and agriculture.

“In the past, urban planning tended to emphasize functional zoning and maximizing facility utilization efficiency. However, given that increasingly frequent natural disasters are now a fact of life, we have to distribute facilities locally to guarantee basic security and give everyone equitable access to services—”

While I was still explaining why the lawns that used to line roads had been turned into wheatfields, Dan Zhu decided to change the subject.

“Have you heard about East Sea City?” she asked Ah Qi and Shang Jun, both still in elementary school.

Since Shang Jun hated being cooped up at home by floodwater, she begged to go on a long trip before the flood season. That was why I had brought the two young girls with me to visit Dan Zhu. The restaurant we were in reflected the cozy small-town atmosphere of Yan City: tiled walls showing their age, elaborate pillars painted in gold, Chinese-style round tables, solid and plain black chairs. In the middle of all that clutter, even the cold mien of the bored owner seemed warmer and kinder.

Shang Jun was clearly intrigued by Dan Zhu’s question. “What’s East Sea City?” The chubby little girl that had almost been lost to the flood all those years ago had grown into a strong and muscular preteen, her face tanned from playing in the sun.

Ah Qi, on the other hand, paid no attention to our conversation. Her unfocused gaze seemed aimed at empty space—absorbed in a game projected onto her MR contacts. She was the youngest of the three girls. The year she began formal schooling coincided with a general push to get all students to make more use of AI assistance in education. As a result, Ah Qi and her classmates thought nothing of leaving reality behind and wholly devoting themselves to the strange and glamorous world of the metaverse. I had to go into the metaverse myself sometimes just to summon her for dinner—and returned alone: as a metaverse native, she knew how to apply filters to my access scope in order to hide her virtual creations from me.

Taking in Ah Qi’s indifference and Shang Jun’s enthusiasm, Dan Zhu turned to me. “I’m sure Jiao has heard about it.” She has never called me “Mama.”

I nodded. “I was involved in the planning for East Sea City.”

Dan Zhu’s eyes suddenly filled with interest. “Really? Why do they want to build a city floating on the ocean?”

“My impression is that initially, some climate scientists studying ocean currents and typhoon patterns discovered a region of relative stability in the East China Sea.” I set down my chopsticks. “Later, geologists found a large petroleum deposit in the same region.”

“And then?” Shang Jun asked, looking at me eagerly.

“Well, then people began to study whether it was possible to build a city over the ocean that’s safe for people,” I said.

“I don’t see how that can be safer than on land,” said Dan Zhu. “But what do you think, Jiao?”

Her tone made me uncomfortable. After matriculating at Yan City University as a civil engineering major, she had been elected president of the student council. Evidently, she was now used to being in control of any situation she found herself in.

“In the event of a catastrophe, it’s obviously much harder to evacuate a city on the ocean than a city on land,” I said. “To be honest, I’m not sure I really understand the logic behind this concept, either.”

“I read an article that said the impulse driving the construction of East Sea City has nothing to do with engineering, but strategic considerations,” said Dan Zhu.

I recalled my discussions with Fei Boyi. During the initial stages of the planning for East Sea City, the planners asked the Da Yu team to be involved. The results weren’t encouraging. I advised them to adjust their thinking: Instead of treating East Sea City as a “city” in the traditional sense, it would be more helpful to view it as an assembly of mobile platforms. In the event of a disaster, the connections securing the platforms in place could be severed, allowing the individual platforms to escape with residents like ships. This would be more effective than a separate evacuation mechanism.

Dan Zhu continued, “Based on what you said about undersea oil deposits, East Sea City is a fleet constructed around an energy source. It’s a good exploration of new urban forms in this age of climate degradation.”

“Well, refining current technologies to improve the space in existing cities is also a good choice,” I said. “Have you thought about why we continue to drive cars, but with external airbags bolted on? Why don’t we switch to sailing around in boats? It’s because city streets are designed with wheeled vehicles in mind. The width, gradient, turn radius, distance between buildings, and other parameters are all fixed. Our cities cannot support ships.”

“But that approach will never resolve the root of the problem.” Dan Zhu raised her voice. “We shouldn’t just stick with models from the past and make incremental adjustments to our cities as they fail. We need to endow them with new ideas, new directions to actively take on the challenges of climate change.”

I gazed at her face, defiantly tilted. “Have you joined the debate club?”

She laughed. “Yep. In fact, ‘Should we build sea cities?’ is the topic for next week.”

“Looks like we should get ready to celebrate your victory,” I said, putting a piece of braised pork into her rice bowl.


The weather in Ze City degraded further. Flood season became a regular part of life. Heat waves, droughts, tornadoes, bad harvests … every year brought new surprises, like the blind boxes at stores. As disasters grew more terrifying, Da Yu had to be upgraded to keep pace. Usually, the escape plans generated by Da Yu made sense, but occasionally its suggestions were incomprehensible.

One spring, we experienced a rare stretch of sunny, calm days. However, during those weeks, Da Yu continued to send evacuation notices to residents around the city. After multiple probes by Fei Boyi and his team, they realized that Da Yu was planning to evacuate the entire city and claimed that this was “the only solution to the problem.”

Stumped, they came to me for a consultation—on the rather dubious premise that my “lack of technical knowledge” made it more likely for me “to take a holistic approach to the problem.” I asked Fei Boyi whether it was possible to add depreciation of real estate into the model Da Yu used to estimate economic damage, so that Da Yu could account for the loss from abandoned housing and infrastructure. It actually worked, and Da Yu stopped trying to get people to abandon the city.

Bugs could be patched, but life in Ze City could never return to the pre-degradation days. Shang Jun and Ah Qi spent the entirety of their elementary school years online, learning from home. Their after-school hours, however, couldn’t have differed more. Ah Qi would keep her headset on and sit still in her room, as though the real world was completely irrelevant. Shang Jun, on the other hand, couldn’t wait to get out of the apartment so that she could watch the robots work on cars in the repair shop or practice climbing with the volunteer rescuers.

On the day that Dan Zhu came to Ze City to visit me, she caught Shang Jun trying to perfect her technique for rappelling with two ropes. As Shang Jun passed my living room window on her way down the side of the residential tower, she saw Dan Zhu and stopped, knocking on the glass to get her attention. Dan Zhu was so shocked that she spilled her coffee. Laughing at the sight, Shang Jun continued her descent. Dan Zhu opened the window and shouted down, “Be careful!”

“Don’t worry!”

Shang Jun loved rock climbing, and spent hours studying safety harnesses, hooks, ropes, knots, and so on. I suspected that this interest was the result of her childhood rescue from the flood by a safety cable.

Dan Zhu returned to the dining table, clearly rattled by the sight she had just witnessed. She wiped the spilled coffee from the table and poured herself a fresh cup. Then, calming herself, she tactfully explained that she thought it would be best for Shang Jun to attend middle school and high school in Yan City. “Ah Qi could come with her.”

I stared at the adult Dan Zhu, tall, slender, calmly stirring coffee across the table from me; the only familial resemblance I could see between her and Shang Jun was the nose. She reminded me of some client waiting for me to deliver a progress report.

“I think the girls should make this decision for themselves,” I said.

Unsatisfied with my deflection, she confronted me. “Why don’t you move to Yan City with them? Have you seen the latest ranking of cities by livability? Ze City is now in the bottom tier, just above the gray ‘unlivable’ tier, the coastal cities that have been completely submerged.” As if to drive the point home, she added, “Ze City is next.”

Why don’t I want to move? I had asked myself that question many times. Based on my own observations, those who had moved into integrated compounds the earliest were also the most likely to stay put. Because our towers were situated on elevated suburban ground, we only had to spend a few weeks every year surrounded by floodwater. With sufficient preparation, most could get through it. Our situation didn’t present the difficult choices faced by residents in the city proper, who had to give up their homes and careers to start again in another city.

“Because that’s my home,” I said.

“Walls do not make a home,” she said. “Home is where you find your family.” Her tone brooked no disagreement, as though stating a fact of nature.

But her words weren’t new to me. I had heard them in ads from East Sea City, trying to attract new residents. In recent years, even cities built on higher elevation, like Yan City, were beginning to suffer flooding due to excess rainfall. People who had moved there from coastal cities, confronted by the prospect of another nightmarish uprooting, decided that it was better to go all the way to East Sea City, a new frontier of promise.

“Are you thinking of moving to East Sea City?” I asked, keeping my tone neutral.

“I’ve already found a job there,” she said. “I’ll be an engineering manager in the energy harbor.”

“I worry about you,” I said, struggling to find the right words. “I … I heard that the facilities over there are primitive.”

“That’s why they need more structural engineers.”

I decided to be direct. “It’s dangerous to live in the middle of the sea.”

“Last month, a tornado swept through Yan City University, only a few tens of meters from where I live. Look, there’s nowhere now that can be considered safe; so, there’s nowhere that can be considered ‘more’ dangerous either.”

The fallacious argument had its own logic. I matched her gaze, but in the end, I was the one to look away. “Be careful out there on your own.”

She laughed, finally free of the web of familial affection and obligation I was trying to weave. The joy soon vanished from her face. “You should take care too, all of you.”

I said nothing. Back when Fei Boyi was patching the bug in Da Yu, he had tried to justify Da Yu’s choices. He explained that for residents, the question of where to live was no longer a matter of mere “habitability,” but an objective matter of life and death. Da Yu was doing its best to help humankind make the right decision.

Maybe it was time for me to think about moving.


“Destination: Yan City!” An excited Shang Jun tapped the virtual AR keyboard suspended in midair with her grease-covered fingers, opening up every map layer available to her: possible locations of mudslides, their estimated flow volume and course, status of the external airbags, number of remaining anchors …

“I saw this awesome video,” she continued, “and the driver was using anchors to make tight turns, like drifting in racing cars!” Her thick brows lifted in excitement.

Ah Qi, in the backseat with her earbuds in and an unfocused gaze, was immersed in the metaverse. Her pale face seemed to glow in the dim interior of the vehicle. She had no interest in the reality around her, despite the dangerous situation we were in. I’d given up on trying to help her in the real world. My biggest insight from watching these three kids grow up was: Sometimes you had to admit that communicating with your own flesh and blood was impossible.

“Da Yu, please calculate the probability that we’ll arrive safely at our destination,” said Shang Jun.

About five minutes earlier, Da Yu had issued a warning that the aerial passageways connecting the towers of the integrated compound were more likely to be destroyed by mudslides. If we didn’t want to be trapped near Ze City, we had to leave immediately. Shang Jun, who was in the repair shop, saw the alert and immediately called us, urging us to get to the parking garage ASAP. But now that we were ready, Da Yu was taking forever with its calculations. The circular cursor on the screen spun endlessly, and everyone grew more anxious with each passing second. Even Ah Qi blinked and emerged from her world to comment, “Come on, Da Yu. Say something!”

“Seventy-nine percent,” Da Yu said, “assuming we leave within one minute.”

I could see the steam coming out of a furious Shang Jun’s head. “Then why are you wasting time?!”

By the time I finally pulled out of the garage, I could hear the thunderous roar of rock grinding against earth in distant mudslides. I couldn’t understand why the others weren’t also leaving—didn’t Da Yu warn them? Waiting around to be rescued seemed too much of a gamble: who knew if the supplies would last until then? Well, maybe I was the only one who didn’t hesitate because we’d already bought an apartment in Yan City and most of the possessions we wanted to take with us had been packed and loaded into the car.

As we merged onto the highway from the ramp, Shang Jun shouted, “Look!” I glanced over to the rearview mirror and saw the passageway leading from the garage collapse under a muddy wave. The wave also swallowed a silver-gray RV, which vanished with barely a splash.

Torrential rain streamed down the windshield, but it couldn’t wash away my terror. There were very few cars on the elevated highway, which added even more to my anxiety.

“Da Yu,” Shang Jun asked, “what’s our probability of reaching Yan City safely now?”

“Ninety-seven percent,” Da Yu replied, with no hesitation. It also marked out several dangerous segments along our course on the HUD. After dodging falling boulders from slopes, the rest of the way was relatively uneventful. As clouds gradually dissipated, the blue sky was so bright that the lush vegetation covering the roadside mountains glinted with a golden light. In the past, I would have felt joy at such a sight, but now I was used to suspecting that every sign of beauty in the world was but a harbinger for some greater disaster, like the calm before the storm.

Although the mudslide that we escaped was comparatively minor, the fact that it struck an area filled with integrated compounds led to a great deal of attention and anxiety on social media. After we arrived in Yan City, waves of refugees joined us, and what was once a relatively small town swelled to a population exceeding a million. As an urban planner, I was inundated with work, and I saw increasingly unusual proposals for new city designs: cities carved into the cliffs of the Qinghai-Tibet Plateau, new developments in warming Antarctica, potential settlements on the Moon and Mars … in comparison, East Sea City no longer seemed like something out of science fiction.

Shang Jun loved all these new ideas. Unlike most people, she was immune to apprehension about future pain, nor did she hesitate over any impending terror. The beautiful visions sketched by these dreamers filled her with hope and faith. At first, she collected the ideas in a private folder, but soon she realized that there were perhaps undiscovered connections between all these different futures. She started a website to collect these fantastic visions of future cityscapes. For instance, when she heard that someone had suggested that the inside of the peaks of the Himalayas could be hollowed out to provide space for cliff-hanging cities, she recorded the idea in her web site as a “seed.” Soon, she had to sort the seeds into various categories and subjects: engineering, geology, sociology, architecture …. She would then send messages to experts in various fields and invite them to grow the seeds, to develop and refine the ideas.

At first, the site had very few visitors. Ah Qi then told her that she should turn it into an open discussion forum. Once Shang Jun adopted her suggestion and welcomed all users to contribute stories based on the various fantastical seeds, the site exploded into a vibrant forest of imaginative urban planning. As writers and readers of various backgrounds iterated on the stories and contributed their own expertise, some of the seeds grew into towering trees.

One time, I clicked on one of the grandest trees in that forest, titled “Huaxia.” It envisioned an amphibious city that was capable of existing on land as well as over water. The inhabitants of Huaxia, thanks to genetic engineering, could withstand the pressure of deep sea and hold their breath for hours, like whales. I was surprised to see that the seed for this idea came from Ah Qi. Although the basic concept wasn’t unusual for a piece of fiction, I loved the childlike and engaging manner in which Ah Qi wrote the first sentences of this speculative exploration. Next to the original seeding sentences, Ah Qi added a note, in which she explained that from the time of her birth, summer was known as the flood season, and water, as a concept, was tinged with terror and danger. She hoped that in this world, she would get a chance to redeem summer into a season of joy and restore water as a realm for play.


I got a request from Fei Boyi for a video call while in East Sea City.

I hadn’t seen him in many years. On the screen, he looked thin, gaunt even. Body weight wasn’t just a matter of aesthetics in this age. When we saw an old friend who seemed to have lost weight on the screen, we instantly became concerned about their health and sustenance.

“Where in the world are you?” he asked, squinting at the scene behind me. “Such blue sky! And those bright clouds! When did you move?” His voice rasped.

“East Sea City,” I said. “I haven’t moved from Yan City. But I do travel here a lot for business.”

“Traveling for business?!” He grinned.

It was indeed rare now to travel for business. However, the city government, concerned with the expansion of East Sea City and the increased risk of a massive fire due to the concentration of linked platforms, wanted to plan specifically against this risk. The peculiar spatial design of East Sea City meant that traditional approaches didn’t work, and the city planners decided that they should invite experts from all over the world for an on-site conference to solicit new ideas. Hoping to give Dan Zhu a pleasant surprise, I followed Da Yu’s directions, which took me on various modes of transportation over a period of two weeks to reach East Sea City.

Upon arrival, I was dismayed to find that Dan Zhu wasn’t in my cluster of floating platforms at all. The designers of East Sea City had taken my suggestion from long ago such that only the oil platform and the harbor based around it were secured to the seafloor. The rest of the city, where most people lived, was constructed from uniform 3D-printed floating units, hooked together into expanding clusters of cells resembling honeycombs. According to Dan Zhu, although she was in East Sea City, her cluster, built around another harbor, was over a thousand kilometers from my location. It would be another two weeks before a ferry would make the trip, and so we still couldn’t meet in person.

I didn’t need to get into all this detail for Fei Boyi, of course, so I just gave him a simple summary. Then I asked, “How have you been?” I really wanted to know.

“Not great,” he said. “I … have something I have to entrust to you.”

His tone was solemn. I tried to keep my expression neutral as I gingerly asked, “What is it?”

“It’s about Da Yu, specifically Da Yu’s intellectual property rights. Back when we first developed it in Ze City, the client only accepted the research results from the trials. The actual IP in Da Yu itself has always remained with my company.”

“But why? Da Yu should be applicable everywhere.” I couldn’t make sense of what he was telling me. Da Yu was now virtually synonymous with disaster navigation systems. Why didn’t the original client want to own it? Surely the potential was obvious even then.

“They were happy with the product, but they didn’t want the responsibility.”


“An error by regular navigation software would at worst leave you in a traffic jam, or perhaps take you on a longer route. But if an emergency survival navigation system suggested the wrong turn, people could die.”

I was beginning to understand what he meant. After the bug in Da Yu that led to the aborted attempt to evacuate Ze City, I began to pay attention to media coverage of Da Yu. While those whose lives had been saved by Da Yu rarely thanked the software publicly, anyone who was put at risk by Da Yu was only too happy to go to the courts, as well as to the court of public opinion. Da Yu suffered from many limitations. For instance, it had very little understanding of the special needs of young children, persons with disabilities, and other populations. As well, even when gas stations were running low on supply, it continued to direct vehicles with empty tanks to them. It was only when everything—the people, the vehicles, the facilities, etc.—all behaved exactly like they did in models that Da Yu’s plans worked out perfectly.

Faced with mounting lawsuits, Fei Boyi had made various concessions. For instance, he backed away from the initial idea of making Da Yu mandatory during red storm alerts. Later, he also added more elaborate TOS screens to the app interface, emphasizing to users that the routes provided by Da Yu were for reference only, and whether to follow them was entirely the user’s choice. Despite all the disclaimers, Da Yu only gained more users.

As if worried that I would refuse, Fei Boyi continued, “The operation of Da Yu is carried out by a separate company. As the IP holder, we hold a controlling stake in the operating company, but there’s little day-to-day work for us. It’s a profitable business. Da Yu now has multiple premium features available only with a subscription—people are willing to pay a lot to be safe during disasters.”

He was so thin that his grin looked like the grin of a skin-wrapped skull. The discussion of catastrophe capitalism disgusted me. “What do you need me to do, exactly?”

“You’ve always owned a part of the IP in Da Yu,” he said, looking ashamed. “But … we haven’t paid you your share of the royalties. I’d like to transfer all the shares in the operating company to you.”

I knew I should tell him “Thanks but no thanks,” but the pleading intensity in his gaze stopped me. So instead, I asked, “Why me?”

“I’ve been thinking a lot about the questions you asked us when we were first designing Da Yu,” he said. “I don’t know who else I could count on to care for Da Yu. The responsibility is too heavy.”


After a storm that lasted many days, Yan City became plagued with mosquitoes and other pests, and diseases ran rampant. Shang Jun died of malaria.

I couldn’t understand it. Shang Jun was the strongest of the three children, and she had rarely been sick throughout her childhood. Dan Zhu, on the other hand, accepted the news calmly. She told me that in our age, every family had to be prepared for the pain of losing loved ones. Five years into her engineering career, Dan Zhu had decided to switch to politics. It suited her much better. With her easy eloquence and strong sense of conviction, she quickly became a star in the East Sea City political scene, gaining power and influence along the way.

Ah Qi stayed by our side, helping me and Dan Zhu with what had to be done for Shang Jun’s death. She finally stopped immersing herself constantly in simulated game worlds. After Dan Zhu returned to East Sea City, Ah Qi seemed to accept the reality of this world and became thoughtful as well as reliable. She took over Shang Jun’s web site and brought it into the metaverse, transforming it into a virtual world called “Huaxia.” Under her management, it grew in popularity by leaps and bounds. Confident that she had found her own path in life, I decided to move back to Ze City alone.

I moved during spring. I saw that the passageway leading back to my old integrated compound had already been restored, and they had even added an access road and a set of traffic lights. Although many of my old neighbors had moved away, maintenance robots had kept the tokamak going, and even the vegetable garden in the lower levels of the support facilities building was growing well, and the winter wheat ready for harvest.

I hired a lawyer to go over the documents from Fei Boyi, who left me the IP rights to Da Yu in his will. I accepted his gift of trust. I was now the owner of Da Yu’s IP, the royalties, and most importantly, the master administrative login and password to the software.

On the day Dan Zhu called me, the sky was dark with thick clouds. It was the busiest time right before the start of the flood season, and the residents of the integrated compound had spread out the wheat kernels to dry on every flat surface available. Dan Zhu was calling from a special phone number, the kind that was rumored to be able to evade AI surveillance of communications. No video.

“We’re investigating Da Yu.” She cut straight to the point, the way she had always done. “Imagine my surprise when I found that Tushan Jiao is the sole IP holder behind Da Yu.”

“I did work on Da Yu. What’s the problem?”

“Why did you agree to take ownership of Da Yu? Have you never doubted it?”

I strode to the window. “What exactly are you trying to say?”

“Da Yu has access to too much data, and the permissions are too broad! In order to facilitate the computation of emergency survival routes, the designers allowed it to see everything: personal information of the residents, vehicle maintenance records, detailed city infrastructure maps, underground pipes and conduits, building plans … I heard that it even has direct control over many urban facilities.”

“All of that is to help Da Yu save lives,” I said.

“But think about the people Da Yu didn’t save. Do you believe it was just a matter of bad luck? In East Sea City, while examining the access records of restricted data, we discovered the simulated escape plans drawn up by Da Yu.”

“Da Yu can’t access any restricted data unless it has been duly authorized. I don’t see the problem here.”

“The problem isn’t the data; it’s the plans,” said Dan Zhu. “We compared successive iterations of its simulated survival plans and realized something odd. Although the number of expected deaths didn’t go down dramatically, the types of people saved in later iterations did change. At first, the changes seemed fortuitous, but in the latest iterations, the expected dead were mostly the elderly and those with chronic diseases. We believe Da Yu is placing different values on different lives, and based on the value, giving each person a different escape route.”

I frowned. “Users can choose to deviate from routes suggested by Da Yu. They’ve always been in control.”

“In the middle of an emergency, are you sure you can choose?” Her tone was superficially calm, but I could sense the suppressed rage threatening to erupt. “Are you certain that everyone even has been given the opportunity to choose?”

I walked to a more shaded area of the living room. “Why are you so angry?”

“You are one of the designers of Da Yu—the only one still alive from the original team. The algorithm inside Da Yu was likely responsible for the deaths of millions.” Dan Zhu paused. When she spoke again, her voice was hoarse. “I don’t want Da Yu to deliberately leave anyone behind, like my parents.”

Only then did I understand that Dan Zhu never got over that day, that day when she thought herself responsible.

Since I didn’t answer, Dan Zhu went on. “We’ll likely be releasing the results of our investigation to the media shortly. But I’ll give you a chance to give me an answer first.”

“I’ll try,” I said.

She hung up.


As I left home, Da Yu warned me that if I went into the city now, my chances of safely returning were only sixty-seven percent.

“I have to go,” I said. Then I entered the destination: the same city center parking lot from years earlier.

Da Yu planned a strange route for me. Since the storm alert was still only orange, I decided to turn off Da Yu and navigate there on the elevated highway by myself. There was almost no traffic heading into the city, but the lanes going the other direction were packed full of cars leaving the city. In less than forty minutes, I reached city center, which was already deserted because of the impending flood.

How strange. Why would Fei Boyi store Da Yu’s historical navigation data here, inside encrypted servers in a nearly abandoned office building in the center of Ze City, where they could be wiped out by a flood?

The entrance was no longer on the ground floor. To deal with the annual flooding, many buildings had been modified so that doors and windows on the lower floors were filled in and sealed. I climbed up the vine-like external stairs until I reached the seventh floor and found the new entrance. I punched in the passcode; the door opened, releasing dusty air that hadn’t been breathed in a long while. Flipping on the lights, the air seemed almost solid with swirling dust motes. I checked the directory next to the elevator: the server room was still at the top floor. Since there was no chance I could trust an elevator that hadn’t been maintained for so many years, I turned to the stairs.

By the time I reached the top floor, my lower back and knees were killing me. Outside the windows, I could see the piles of charcoal-gray stratocumulus clouds, with only bits of white in a few distant wisps. The door to the server room was heavy and provided a good seal, and I found the inside relatively clean and undisturbed.

As Dan Zhu had noted, the initial training of Da Yu was based on a digital twin of Ze City. Since the development of Da Yu required unprecedented access to the city’s data, the confidentiality provisions governing Da Yu itself were likewise extremely strict. Even after Da Yu was operational, the historical navigation records were kept under lock and key, with no publicly accessible online copy. The only place to review the data was right here in this room. It was also here that the project team had met all those years ago, analyzing trial results and debating optimization approaches. Since the topics of discussion were so sensitive, most of the notes were handwritten, and I could still see pages tacked onto the walls.

I used the credential Fei Boyi gave me to log on to the server. Whatever the results of Dan Zhu’s investigations, I also wanted to know the truth for myself.

Soon, I found the time sequence that interested me: the day I rescued Dan Zhu and Shang Jun under Da Yu’s guidance. I learned that on that day, after the red storm alert had been issued, Da Yu generated approximately 650,000 separate escape routes. Of that number, approximately 390,000 trips led to successful escapes that reached their destination.

Those numbers, by themselves, told me little. Why did the other users fail to reach their destination? Maybe they didn’t trust Da Yu and refused to follow its guidance. Or maybe unexpected events intervened—like the billboard that fell on top of the van.

I randomly examined a few trips but found nothing particularly convincing. I tried to pull up the records for another date: the day we departed Ze City and moved to Yan City. Once I zoomed in on the area of interest, I found Da Yu’s mudslide warning. On that day, of the three-hundred-plus households in my integrated compound, about one hundred households received the mudslide warning. Of the households that didn’t receive the warning, most were elderly. But this was not the same as proof that Da Yu purposefully left them behind. Maybe most of the elderly didn’t subscribe to Da Yu’s services.

It was going to start raining soon. I swiped through the documents quickly. There was no time for me to analyze the raw data myself. My hope was to find some applicable analysis that Fei Boyi had done in the past.

Where would he have hidden this information?

I found a directory named “Business,” which contained a single document with a promising title, “Performance Analysis.” The content, however, was disappointing. Fei only had very high-level data: Compared to Gun, Yu improved successful escapes by fifty-seven percent, lowered economic loss by thirty-five percent, and so on. But these numbers couldn’t answer Dan Zhu’s question: Were Da Yu’s escape plans fair to every single individual caught in a disaster?

I stood up and paced around. I needed to change my approach.

If Da Yu was trying to place a value on individual lives, what was the purpose?

Looking up, I saw a piece of paper tacked to the wall. The handwriting was mine: “Traffic jams.”

At the time of the original Yu project, the client had wanted us to replace Gun with Yu because before that flood season, Ze City had suffered a massive citywide traffic jam. In a disaster, if everyone wanted to leave by the elevated highway, the result was certain to be a massive jam that prevented anyone from leaving, leading to catastrophic loss of lives. News reports focused on one particular story from that time: a family of three, who started out only four kilometers from the entrance to the elevated highway, had drowned because they couldn’t get onto the highway even after three hours.

Next to the words “traffic jam,” I had also written “divert and channel.” I could almost hear Fei Boyi’s voice: “The escape routes computed by Gun were basically correct. If we could figure out a way to channel the flow of people and vehicles instead of letting everyone head for the exit all at once, we should be fine.”

Was Da Yu trying to “channel” the flow of refugees? To keep the roads open?

I exited the secure server room and reconnected to the wireless network. An alert popped into my AR view.

“Da Yu,” I summoned the software.

“At your service, Ms. Tushan Jiao.” The synthesized voice spoke at a rapid but still comprehensible clip, a subtle bit of optimization for emergency situations.

There was a window open at the end of the hall, and the wind that roared through the corridor was redolent with the scent of mud. “What’s the current status?” I asked.

“There are flash floods coming down the mountains beyond your view. The torrent will reach your location in three minutes. I strongly recommend that you take the elevator and depart immediately. I’ve already called the elevator for you and it’s waiting.”

I walked into the stairwell instead. “Da Yu, tell me what you think of people who, despite your help, don’t survive?”

“I’m sorry, but you must trust me,” the synthesized voice said. “You’ll make it only if you take the elevator. The flooding is about to reach the parking lot.”

My painful knees slowed me down. By the time I descended to the seventh floor, more than three minutes had passed. I pushed open the door. The dense raindrops were coming down like solid silver threads, glinting coldly against the dark silhouettes of the swaying trees. The rain wasn’t quite strong enough to flood this place, not yet.

“You’re too slow. We’ve run out of time,” Da Yu said. “I suggest you return up the stairs immediately.”

“I’m going to the parking lot,” I said.

“No, there isn’t time,” Da Yu said. “Please go up the stairs. It’s safer up there.”

I had no intention of being trapped in an abandoned office building for the entirety of the flood season. I walked toward the parking lot. The rain became heavier, and with a loud rumble, the sky seemed to open up, pouring down sheets of water. Ignoring Da Yu’s insistent pleas for me to turn around and climb up the building, I made my way to the parking lot, which was still unflooded. “It seems that your calculations are off, Da Yu.”

“I’m trying to make corrections based on the new data. Please wait a moment.”

After checking the external airbags, I got in the car, dragging my balky leg. The familiar Y-shaped glow flashed over the windshield HUD. It was as though I was once again living through that day from long ago.

“I don’t recommend you head for the elevated highway,” Da Yu said. “Please take the southern exit. It will be a longer route, but safer.”

Why is it constantly trying to get me to take the longer route? I glanced at the course it suggested, twisting and winding like a Chinese decorative knot. Inspiration struck me as I used my administrative privileges to modify my account so that I appeared as Dan Zhu to Da Yu. “Find the fastest way home, Da Yu.”

“No problem,” said Da Yu in a relaxed tone. “We have plenty of time. The fastest way is taking the elevated highway.”

“What are the chances of my safe arrival home?”

“One hundred percent.”


By the time I opened the door to my unit, it was completely dark. A shadow stood at the window, back toward me. It wasn’t exactly unusual to find strangers seeking shelter in one’s home during flood season. I flicked on the light, intending to tell them that there were plenty of empty units in the rest of the tower.

The figure at the window turned around. Dan Zhu.

I hadn’t seen her since Shang Jun’s funeral. She was still thin, her complexion dark from the sun, which made her resemble Shang Jun more than before. The wrinkles at the corners of her eyes made her gaze appear even sharper.

“When did you get in?” I poured a glass of water for her.

“I’m here in Ze City for business. When I called you this morning, I was already on the way.” She accepted the glass but made no move to sit down. Still standing, she said, “Have you already gone into the city to confirm what I said? You’re always so capable.”

“You’ve been monitoring me?” I disliked the feeling of being watched by her. “I guess I don’t need to tell you anything. You already have your answer.”

“I know that Da Yu filters people in the name of ‘effective survival.’”

“Effective survival?”

“How can you not know what that means? It’s all over the place in Da Yu’s design documents.”

“I’m not an AI specialist,” I said. “I wasn’t involved in the core programming of Da Yu. How does it evaluate people? By their age?”

I had already done a few tests beyond switching to Dan Zhu’s identity. When I pretended to be Ah Qi, the probability of safely arriving at home was also one hundred percent. But when I switched to the accounts of a few other friends around my age, the probability drastically decreased. Even people in their fifties seemed to be treated as “aged.” I didn’t like that at all.

“It’s not that simple,” Dan Zhu said. “Looking at the results, it can appear as though the survival rate is correlated with age. But the actual mechanism employed by Da Yu is driven by complex big data approaches. It prioritizes escape by those who have a higher chance of surviving subsequent disasters.”

I remembered the arguments I used to have with Fei Boyi. He had little patience for concepts I brought up such as uniformity or equity. “I have no time for slippery, fuzzy ideas. Our goal is to increase the survival rate of the population as a whole. For that I need quantifiable parameters: lowering the number of deaths, minimizing economic loss, and so on. It’s inevitable that some will be prioritized over others.”

“Da Yu’s approach is rational,” I said to Dan Zhu.

“It’s not fair to many.”

She reminded me of my own questions to Fei back then. “Who? Who is ‘prioritized?’ Who gets to decide who should be prioritized?”

The answer had always been clear. The young, the ones who were capable of matching the speed necessary for Da Yu’s escape plans, the ones with more “value.” I wondered if Fei Boyi himself, not in the best of health near the end, had also been filtered out by Da Yu.

“How does Da Yu pick the winners and losers?” I asked.

“We aren’t sure,” said Dan Zhu. “The core algorithm is a black box. Who knows. Maybe even the posts on Huaxia play a role in its decision-making process.” She laughed with little mirth. “We’ve already taken Da Yu out of operation in East Sea City. Right now, the residents of Ze City are still trying to escape under Da Yu’s guidance. I’m very curious. How will you decide? Will you shut down Da Yu?”

Turning off Da Yu is a choice. Devoting more resources to improve its algorithm is also a choice. Each choice comes with responsibility. The best choice is of course to save everyone. But if only so many people can safely flow through the escape routes within the allotted time, what is the best choice?

And who is going to define “best”?

“If I shut off Da Yu now, will more or fewer people die?” I asked her.

Is the world really fairer without Da Yu?

“I don’t know,” she said. “But right now, the choice is in your hands. You’re safely at home, but many others are still on the road. Will you change their fate?”


“Please confirm system shut-down.”

Some aspects of Fei Boyi’s interface design were truly puzzling. Although I had to go in person to examine the historical navigation data, turning Da Yu off was something that could be done remotely. Sitting in the car, it took me no time at all to log on to the system as an administrator and find the right menu page.

Dan Zhu had already left after taking a call, telling me that she had other business to handle. She was no longer the girl who sobbed in silence. She had learned to throw the toughest problems at me.

I drove out of the garage and into the rain. Distant mountains sketched blurred patterns on the windshield, smudges of pale green. The red glow from a traffic light lit up the road before me.

I stopped. Should I really go forward? All choices come with costs. If the cost is the lives of those who are powerless, is it right to sacrifice them in the name of some greater “good”?

My gaze froze on the “Confirm” button. Am I ready to shut off Da Yu? When we’ve been stripped of artificial intelligence, of East Sea City, of the seeds of hope planted on Huaxia, we must admit our naked humanity, standing alone between heaven and earth, facing the greatest of terrors with our insignificant selves.

The light turned green. I logged out of the administrative account for Da Yu and turned onto the access road. The Y-shaped glow winked out on the windshield.

The night was already dark. Thunder and lightning danced in the distant mountains; they were coming, but not yet.

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