Jake Morrison lived in a apartment in Harlem that smelled like old coffee and regret. It was a third-floor walk-up with windows that faced a brick wall and a fire escape that rattled every time a train passed. The radiator clanked like a dying engine. The landlord was a ghost. The building was a ghost. Jake was mostly a ghost too, or at least he had been since they laid him off from the hedge fund.

He was thirty-five years old and had not spoken to another human being at length in three weeks.

On a Tuesday--he was fairly sure it was a Tuesday, the calendar on his wall had not been updated since February--Jake was sitting in front of his computer, scrolling through satellite data that he had downloaded from a public government database. He was not supposed to be doing this. He was not a scientist. He was a former data analyst who had spent five years optimizing trading algorithms and three months cleaning his apartment after the layoff. But he had noticed something, and noticing things was the only skill he had left.

The pattern was in the noise. Buried in the radiation readings from a deep-space probe--the Voyager-IV, launched in 2019, currently somewhere beyond the orbit of Neptune--there was a repeating signal. Not natural. Not random. The kind of signal that had a structure, a grammar, a mathematics to it.

He had found it by accident. He was running a noise-filtering algorithm on the data--something he had written for fun, to pass the time--when the filter spit out a pattern that made his blood go cold.

Prime numbers.

Not random noise. Prime numbers. One, one, two, three, five, eight, thirteen--the Fibonacci sequence, the mathematical signature of intelligence. The kind of signature you left when you wanted someone, somewhere, to know that you were not an accident of physics.

Jake sat back in his chair and stared at the screen. His apartment, with its peeling paint and rattling radiator and brick wall outside the window, seemed to shrink around him. The signal was coming from deep space. The signal was artificial. The signal was a message.

He called Sarah.

Dr. Sarah Chen had been his graduate school colleague at MIT. They had not spoken in two years, not since the argument about her paper on signal processing that Jake had publicly criticized on a forum. He had been an idiot. He still felt like an idiot.

"Jake," she said when she answered. Her voice was tired. "It has been a while."

"Sarah, I found something."

"Jake--"

"Wait. Just wait. It is in the Voyager-IV data. A repeating pattern. Fibonacci sequence. It is not natural. It is not noise. It is a signal from outside the solar system."

There was a long silence. When Sarah spoke again, her voice was different. Careful. Measured.

"Jake. Send me the raw data."

He did. Within an hour, she called back.

"I have run my own filters," she said. "You are right. The pattern is there. But Jake--I checked with CERN. We have seen this before. Or rather, something like it. In the data from the Kepler array. And the SETI archive. And the New Horizons telemetry."

"So it is real?"

"It is real. But it is not what you think it is."

Jake's stomach tightened. "What do you mean?"

"Jake. The Voyager-IV was launched from Earth. The Kepler array is orbiting Earth. New Horizons was launched from Earth. Jake--the signal is not coming from outside the solar system. It is coming from inside it."

The room stopped moving. Jake gripped the edge of his desk. "What are you saying?"

"I am saying," Sarah said, very carefully, "that the signal is a reflection. Of our own broadcast. The Voyager probes carry a message--a recording of sounds from Earth, images, greetings in fifty-five languages. That signal is bouncing off a dust cloud in the outer solar system and returning to our own probes. The dust cloud is bending the signal back toward us. What you are seeing is not an alien signal. It is humanity hearing itself echo."

Jake sat down. Hard. "An echo."

"An echo. The 'dark forest'--the thing you have been thinking about, haven't you? The idea that there might be something out there, something watching, something dangerous--it is not real. There is no forest, Jake. There is just... space. And us. And our own voice, coming back to us from the dark."

He was quiet for a long time. The radiator clanked. A train rattled the fire escape.

"So the signal is just--"

"An echo. Of us. Of our own voice, bouncing off dust and returning after decades. The pattern you detected is the Fibonacci sequence, which is not alien mathematics. It is mathematics. The kind of mathematics that humans invented, that anyone with a brain can discover. You found our own math, coming back to us, and you thought it was a message from someone else."

Jake looked at the screen. The prime numbers. The Fibonacci sequence. The beautiful, devastating echo.

"Nobody out there," he said.

"Nobody," Sarah said. "The universe is empty, Jake. As far as we know, it is completely, utterly, devastatingly empty. We are alone."

He hung up and sat in the dark apartment, surrounded by the evidence of his own intelligence bouncing back at him. The signal repeated itself, endlessly, carrying a message that only he could hear, from a destination that only he had created.

The empty forest. The echo in the dark. The voice of humanity, calling out into a void that did not call back.

Jake sat in his chair and listened to the signal repeat itself, one, one, two, three, five, eight, thirteen.

He was the only person in the universe who knew.

The signal kept repeating. Jake kept listening. And the empty, beautiful, devastating universe went on being exactly what it had always been: everything, and nothing, and us.