The Distance Between Doors

Rita could knock on her sister’s door with her elbow without setting down the laundry basket. She had done it for thirty years: two taps against the wood, one step sideways, and Mar would open before Rita had to put the basket on the floor.

In the public archive of Las Eras, the gesture ended against a wall.

“Again,” Rita said.

Santiago restarted the route. They appeared at the foot of the virtual stairs, climbed to the second floor, and turned onto the landing. Rita’s door retained its honey-colored paint. Across from it stood the Medinas’ door. Where Mar’s blue frame should have begun, the model had generated an electrical panel.

Rita moved forward again. The panel became a window.

“It is not confusing the door with something else,” Santiago said. “It no longer has it.”

Las Eras had spent four years beneath the new highway extension. Before demolition, the council gave cameras to the residents and recorded hundreds of routes: facades, kitchens, courtyards, corridors. With the full equipment of the computing center, the neighborhood could be preserved almost in its entirety. The version intended for schools, libraries, and home visits retained only thirty high-resolution fragments.

Everything between them was regenerated as visitors moved.

The archive decided what to keep by position. It stored recent views and retrieved older ones when a visitor returned near the point from which they had been recorded. When the memory bank filled, it evicted the fragment that was most spatially redundant.

In the system’s language, the six homes on Rita’s landing were almost the same place.

Barragán’s property, across the road, occupied five. The house, well, greenhouse, shed, and gate stood far enough apart for the archive to treat them as separate memories.

“It even remembers where he kept the lawn mower,” Rita said. “My sister does not get a door.”

“The archive did not choose that.”

“Decisions no one makes always favor someone.”

Santiago had worked as a municipal draftsman. After retiring, he helped classify the footage and learned where the system hid its technical preferences. He showed Rita the landmark bank. The first two fragments could not be evicted: the station and town hall, fixed at startup to give the model stable references. The other twenty-eight competed whenever a visitor opened a long route.

“We could separate the door coordinates,” Rita said.

“We would preserve the doors and destroy the landing.”

“It has already been destroyed.”

“That is why we should not demolish it again inside the archive.”

Santiago enlarged the initialization log. For a few seconds, before the archive sealed the public version, an operator could alter the order in which fragments entered the bank. If the first memory was a panoramic view of the landing, it would remain protected. The model could recover the geometry of all six doors from it without pretending they stood farther apart.

“What would be second?” Rita asked.

Santiago pointed at the station.

“We keep this one. Town hall enters later like any other place.”

“And if it gets evicted?”

“Then it will change when people return to it.”

Rita smiled for the first time that afternoon.

Santiago’s access had expired. Rita’s had not. Every former property owner retained a credential for validating a home before opening day. The credential allowed metadata corrections, not changes to startup order. Santiago knew how to elevate it for ninety seconds through a calibration console the council had forgotten to remove from the neighborhood association.

The change would be signed with Rita’s name.

“What can they do to me?”

“Withdraw the supplemental compensation. Charge you with altering a public archive. Bar you from entering again.”

“I already spent the compensation on the deposit for my new flat.”

“Then they can ask for it back.”

Rita looked at the electrical panel where Mar’s door had been.

“When?”

The archive would be sealed at five in the morning, three hours before the opening ceremony.

Barragán found them at four twenty-seven. He entered the association office carrying a toolbox and stopped when he saw the console lit.

“The back door was open,” he said.

“You opened it,” Rita replied.

Barragán set the box on the floor. He was also part of the validation group. Since his wife’s death, he visited the virtual greenhouse every Sunday, sitting among plants the model never watered and listening to a radio that made no sound.

“If you put another landmark in, something comes out.”

“Yes.”

“It could be mine.”

Santiago opened a simulation. With the landing protected, the most redundant fragment was one of two views of the pediatric clinic’s corridor. Next came the cooperative’s facade. Barragán’s greenhouse survived because nothing stood near it.

“You always survive by being far away,” Rita said.

Barragán stepped close enough for her to smell the oil in his toolbox.

“I did not choose for my house to be far away.”

“We did not choose to live together so it could count as a single thing now.”

Neither raised their voice. The argument needed no volume. It fit entirely inside the landmark list.

Barragán studied the panoramic view of the landing. Mar had filmed it with a borrowed camera from the stairwell. It showed all six doors, the handrail, and the convex mirror the residents had installed to watch the elevator. The reflection contained half the corridor that lay outside the frame.

“The model is bad with mirrors,” he said.

“It is better with this than with an invented wall,” Santiago replied.

The countdown to sealing dropped below thirty minutes.

Barragán could call the municipal supervisor. He could also unplug the console. Rita stood in front of the socket, knowing she could not have prevented either action.

“My wife spent her final months in that greenhouse,” he said.

“My sister has nowhere else.”

Mar had died before the expropriation money arrived. She had not moved into a new flat or left behind a new kitchen for her children to photograph. Rita had the laundry basket, two cups, and the video of the landing.

Barragán opened his toolbox and took out a fiber adapter.

“This console drops its connection during sealing,” he said. “You will not finish over Wi-Fi.”

He asked for nothing in return. That unsettled Rita more than a condition would have.

They connected the adapter. Santiago prepared the privilege elevation. Rita inserted her credential and read the warning assigning the validator responsibility for any change to geometry, provenance, or memory priority. She accepted.

For ninety seconds, the archive stopped being a neighborhood and became an empty list.

Santiago loaded the panorama of the landing first. The station followed. Town hall entered third, then the water tower, school, greenhouse, and the other places chosen over months of meetings. When the thirty-first fragment arrived, the pediatric clinic lost one of its two views. Mar’s door remained inside the protected panorama.

The system sealed the version with six seconds left.

Rita tried to open the route, but her credential had already been suspended.

“That was fast,” she said.

Santiago could not enter either. Barragán closed the console and put away the adapter.

“I have a validation copy at home,” he said. “They will not have revoked it yet.”

They watched the opening ceremony from Barragán’s living room. On the official broadcast, the mayor appeared inside the station and walked down Calle Mayor with two children. When they reached town hall, one window changed size. No one seemed to notice.

Then they chose Rita’s building.

The archive retrieved the panorama as they approached the stairs. All six doors appeared at once, without exchanging colors or mail slots. The children ran along the landing. One stopped at the convex mirror and waved at his reflection.

Outside, a municipal car parked in front of Barragán’s house.

“You can say we forced you,” Rita said.

“I did not help you for your sake.”

“I know.”

Barragán downloaded the validation copy to a private server and sent the link to the neighborhood association. Then he opened the front door to wait for the inspectors.

Rita put on the headset. She entered the landing through the copy they had just saved. Her door stood across from the Medinas’. One step away began Mar’s blue frame.

She raised her arm as if the laundry basket still rested against it and knocked with her elbow.

The archive could not give her sister back. It preserved the exact sound of the two taps, and the small distance that had once made the gesture possible.

Scientific note

This story is based on the preprint “ReWorld: An Interactive World Model with Long-Horizon Memory”, by Zhifei Chen, Luozhou Wang, Guibao Shen, Dongyu Yan, and collaborators, submitted to arXiv on August 24, 2026.

ReWorld generates interactive video environments and attempts to remain consistent when users return to previously visited positions. At inference, it uses a bounded cache backed by a bank of fragments associated with camera poses. It retrieves landmarks nearest the current pose and, when the bank is full, evicts spatially redundant information. On experimental out-and-back routes lasting up to 64 seconds, it retained revisited views better than other bounded-memory policies.

Las Eras, the heritage archive, its thirty landmarks, and the sabotage are fictional. The paper does not store human memories or determine the cultural value of places. It evaluates generated video; memory is indexed only by camera pose, and dynamic environments remain a limitation. This is a v1 preprint.

Read the preprint on arXiv