The Deep Scan was built four hundred meters beneath the northwestern desert.
From the surface, there was nothing there: endless gravel, a few tire tracks, a lone derrick. Underground, you could see the boldest machine in human history—two vacuum tubes, each three kilometers long, laid out at right angles, suspending the largest Bose-Einstein condensate matter-wave ever prepared by humanity, cooled to within one billionth of a degree of absolute zero. Two laser systems, with attosecond precision, steered these waves apart and back together, reading their interference fringes at the meeting point.
Theoretical physicists had argued for a century: at the smallest scales, is spacetime a continuous brocade or a granular fabric? General relativity said smooth; quantum mechanics said boiling. Each theory was undefeated on its own turf, and annihilated the other on contact. Jiang Li's machine was to be the judge that settled it once and for all.
There was a graduate student on the team, Luo Jian, twenty-five, with a tuft of hair that always stuck up, talking like a machine gun. The first time he went down the shaft, he touched the insulation of the vacuum tube and asked Jiang Li, "Professor Jiang, what if we measure nothing at all?"
"Measuring nothing is also a result," Jiang Li said. "It would prove spacetime is smoother than any scale we can probe."
"And what if we do measure something?"
"Then we go down in history."
"And what if we measure something... strange?"
Jiang Li glanced at him. "In science there is nothing strange. Only things not yet reconciled with the accounts."
Years later, recalling this moment, Luo Jian said it was the bravest and most naive sentence he had ever heard in his life.
The experiment ran for three years.
Year one, calibration. The vacuum leak rate wouldn't meet spec, the laser phase noise wouldn't settle, the geological background vibration was like a beast that never slept. The team changed plans seven times; Jiang Li lived underground for forty days straight, emerging gaunt and hollowed-out, only her eyes frighteningly bright.
Year two, data collection. The data was as flat as desert weather: spacetime, at a three-kilometer baseline and an effective precision of ten to the minus nineteenth power meters, was smooth, perfect, flawless. General relativity won another round. Someone suggested packing up and publishing; Jiang Li stared at the screen full of smooth curves and said the one sentence that sent a chill down everyone's spine:
"Too smooth."
"Nature has nothing this smooth," she said. "Polishing to this degree costs money."
In the autumn of the third year, they pushed sensitivity another order of magnitude, reaching ten to the minus thirty-fifth power meters—the threshold of the Planck length.
The anomaly appeared.
First, a grid emerged in the interference pattern. Spacetime did indeed have a smallest scale—that alone was worth a Nobel Prize, enough to rewrite every physics textbook. Luo Jian ran three laps around the underground facility clutching the printed pattern. But what truly made Jiang Li's blood run cold in the pre-dawn lab was something else.
The behavior of those grid cells did not resemble natural objects.
It resembled response.
Wherever the instrument probed, the data there "filled in," quickly and eagerly; and in the directions the instrument was not looking, physical quantities maintained a statistical state of "incompleteness"—not random, not chaotic, but a nearly indolent vagueness, like a painting with only its foreground done, like an engine that renders only when the camera sweeps past.
Luo Jian leaned in and stared for a long time, then said the sentence that would be quoted ten thousand times: "Professor Jiang, this universe... why does it look like it wasn't given global illumination?"
Jiang Li did not laugh. She sat before the screen all night, replaying in her mind three years, thirty years, three hundred years of physics.
She recalled the double-slit experiment from over a century ago. When a photon is not observed, it travels every path, a cloud of probability; once observed, it "decides" which path it actually took. Einstein lost sleep over it, saying "God does not play dice"; Bohr shot back "stop telling God what to do." For a century people called this the philosophical quirk of quantum mechanics, wrote it into textbooks, and walked around it.
She recalled the Planck length. Why should length have a smallest unit? Why is smaller "meaningless"? Under any natural philosophy this makes no sense—why would nature go on strike at some scale?
She recalled the speed of light. Why should there be an upper limit at all? Why is this limit the same for everyone—no matter how fast you chase it, light is always faster than you by that three hundred thousand kilometers per second? This doesn't look like a law of physics. It looks like—bandwidth.
She recalled Heisenberg's uncertainty. Why can position and momentum only ever be measured precisely one at a time? Why energy and time likewise? Pair after pair of physical quantities, as if by agreement, lifting one gourd only to sink the other. This doesn't look like the nature of the world. It looks like—the precision ceiling of a compression algorithm.
She also recalled quantum entanglement. Two particles half a universe apart; measure one, and the other instantly "knows." Transfers no energy, violates no light-speed limit, just knows. For a century physicists invented countless interpretations—many-worlds, hidden variables, retrocausality. But if you think of them as two references to the same piece of data—distance an illusion of the interface, the underlying layer holding only one address—then there is nothing strange at all.
And the starry sky. Hundreds of billions of galaxies, each with hundreds of billions of stars; wherever the telescope points, only there do details "fill in." She thought of the open-world games the younger generation played: distant mountains are low-poly, and only when you draw near do the high-resolution textures load. The ancients said "a world in a grain of sand"; she had taken it for poetry, but now it read like engineering documentation.
For a century, all these "whys" had been dismissed as "nature is simply thus."
That night, staring at the breathing, flickering grid on the screen, Jiang Li suddenly realized they were not "simply thus."
They were budget.
Details no one looks at are not worth computing. Below resolution, not worth existing. No signal is worth traveling faster than the bus. A pair of physical quantities in simultaneous high definition is not worth storing. Distant backgrounds are not worth rendering.
This universe was stingy to the bone—
because it was saving electricity.
Dawn came. Luo Jian walked in yawning, saw Jiang Li still sitting in place, the screen's light flickering across her face. He leaned in and saw a line written on her notebook, written and crossed out, crossed out and rewritten:
"If this is true, what is death?"
Luo Jian froze. "Professor Jiang, you..."
"Little Luo," Jiang Li's voice was calm, calm as if underwater, "if this world is rendered, then the one rendering it—or the thing—must be poor enough to have only one kilowatt-hour of electricity. One kilowatt-hour has to burn to the end of heaven and earth. Tell me, what would it be most reluctant to spend?"
"Computing power?"
"No." Jiang Li said. "Memory. Computing power can be rationed; time is free. But there is only so much memory—load one thing, and there's one less."
She stood, walked to the whiteboard, and wrote a line:
"Birth and death exist because memory is finite."
Luo Jian said later that at that moment he was not afraid; he just suddenly wanted to cry, and didn't know why.
Jiang Li scheduled the full-power scan for 3:17 a.m., one week later. She would use the machine's full power to drive the probe directly beneath the grid—into that forbidden zone of "below resolution, not computed." The project committee approved reluctantly; in the report she wrote only one sentence: "To verify the response pattern of spacetime's underlying structure to probing behavior." No one knew what she truly wanted to verify.
She herself did not know either. She only knew that for the first time in eleven years, she felt the question "where did Niannian go" might really have an answer.
And the answer was not in the sky.
It was underneath.