The Ten Billion Second Signal

The laptop chimed at two in the morning, and it was not the friendly chime.

"That's the alert sound," Soren said. "Ravi said if it does the two-note thing, come get him."

Maya was already reading the screen. "GRB. Then numbers. Then a sky position."

"Gamma ray burst." Soren opened his notebook and copied the numbers before they could scroll away. "A satellite caught it. It's asking observatories on the night side to swing around and photograph the spot before it fades."

"So we swing around."

"We're supposed to get Ravi."

Down the hall, Ravi was asleep in a folding chair with headphones on. He had been awake for two nights running a survey and had told them, at midnight, that if the sky itself cracked open they should wake him gently.

"The sky did kind of crack open," Maya said. "Look at the distance estimate."

Soren looked. Then he looked again, the way he did when a number seemed wrong.

"That says the light traveled for about eleven billion years to get here."

"Eleven billion."

"The whole universe is only about fourteen billion years old." He set the pen down. "That light left before the Earth existed. Before the Sun existed. It's older than the ground we're standing on."

Maya pulled the second chair over. "Type the position into the scope. It fades. Ravi said it fades fast. We can wake him and lose it, or catch it and wake him."

Soren keyed in the coordinates. The dome above them groaned and began to turn, the telescope hunting across the dark toward a patch of sky near nothing, no bright star, no planet, just a smudge of ordinary blackness between two dim points of light.

"There's nothing there," Maya said.

"There's nothing there that we can normally see." The scope stopped. Soren started the camera. "Thirty second exposure."

They watched the counter tick.

"Tell me what a gamma ray burst is," Maya said. "The real thing. Not the alert-sound thing."

Soren thought about how to say it. "When a really huge star dies, or two dead stars crash into each other, for a few seconds they throw out this beam. Ravi's poster in the hall says it in one line and I didn't believe the line."

"What's the line."

"It says one burst releases more energy in a few seconds than the Sun will release in its entire life."

Maya waited. "The Sun's whole life is a long time, though."

"Ten billion years. The Sun burns for ten billion years, steady, the whole time the Earth is here and long after we're gone." He tapped the poster line in the air like he could still see it. "Every second of ten billion years. All of that light, all of that heat, everything the Sun will ever make. A gamma ray burst does more than that. In a few seconds."

The camera counter reached thirty. An image bloomed onto the screen, grainy, gray, a scatter of faint dots.

"Which one," Maya said.

Soren pulled up the reference chart, the same patch of sky photographed on an ordinary night. He set the two side by side.

Maya found it first. She always found it first. Her finger landed on a single dim point in their new image, a point that was simply not there in the reference.

"That one. It's not on the old chart."

Soren checked it three times against the coordinates. "That's it. That's the afterglow. That's what's left of the burst."

They both leaned in toward a dot so faint you had to want to see it.

"Okay," Maya said slowly. "So that little smudge. That's eleven billion years away."

"Give or take."

"And it's throwing out more power than the Sun does in ten billion years."

"For a few seconds. It already stopped. What we're looking at is the glow cooling down."

Maya sat back. She was quiet, and then she said the thing that made Soren pick the pen back up.

"Then the light hitting this camera right now. Some of it started before the Sun was born, crossed the whole universe, missed everything, and the only thing in eleven billion years that it ran into was us. This telescope. Tonight."

Soren wrote that down. His hand was not quite steady.

"It didn't run into us by accident," he said. "The satellite caught the gamma rays first and told everybody to look. So somebody built the satellite. And somebody built the alert. And somebody wired this little observatory into the network so that a burst from before the Earth existed could ring a laptop in a town with one gas station." He looked at the two-note alert still blinking. "It rang here so we'd point something at it before it was gone."

"And we're the ones who pointed."

"We're the ones who pointed."

Maya looked at the faint dot for a long moment. "There are people who feel too big for a small town. I always thought that was the wrong way around." She tapped the screen, gently, right beside the dot, not on it. "The town isn't small. The dot came eleven billion years to get to it."

Soren copied the burst's official name into his notebook in careful letters, the string of numbers that meant a specific dying star at a specific corner of the early universe, a thing that would never happen again.

"We should wake Ravi now," he said. "We caught it. He can measure it properly."

"In a second." Maya wasn't moving. "How long until it fades all the way?"

"Hours. Maybe a day. Then it's gone. Nobody ever sees this exact one again, ever."

So they sat, the two of them, in front of a gray image of a point of light that had outshone every star that would ever exist, for a few seconds, eleven billion years ago, and was now dimmer than the streetlight outside.

"Go get him," Maya said finally. "Gently."

Soren stood. At the door he stopped and looked back at the screen, at the faint dot still holding steady on the glass, and he did not go through the door yet. He came back and started a second exposure first, so they would have two, so the fading would be written down.

The dome turned a few degrees to track the sky, keeping the dead star centered, and the counter began again to climb.