The Star That Was Too Old

The library book was older than both of them put together, and it smelled like it. Soren had pulled it off the bottom shelf because nobody else ever did.

"Listen to this," he said. "There's a star called the Methuselah star. This book says it might be sixteen billion years old."

Maya was lying on the floor with her feet up on a chair. "So?"

"So the universe is about fourteen billion years old."

She took her feet down.

"Say that again," she said.

"The star is older than the universe." Soren held the page toward her like it might do something. "That's what it says. The star is older than the thing the star is inside of."

Maya sat up all the way. "That's wrong."

"I know it's wrong."

"No, I mean it's wrong wrong. You can't be older than the box you came in." She crawled over and read the page upside down, then right side up. "Where did they get sixteen?"

"It doesn't say. It just says sixteen."

Maya pulled out her tablet and typed Methuselah star with two fingers, fast, getting the spelling wrong twice. "Okay. Newer number. HD one-forty, two-eighty-three. They say maybe fourteen and a half billion."

"That's still older than the universe."

"Barely." She kept reading. "Wait. There's a plus-or-minus."

Soren leaned over. "A what?"

"A plus-or-minus. After the number. It says fourteen point four six, plus or minus eight hundred million years." She looked up. "Why would you write a number and then say you might be eight hundred million years off?"

"Because you might be," Soren said slowly. He flipped to the back of the old book, where the hard pages were. "Look. Even in here. Every age has a little tail on it. Plus or minus. They never just say the number."

Maya was quiet, chewing the inside of her cheek.

"Try it," she said suddenly. "Do the universe one too. Find the plus-or-minus on the universe."

Soren typed it into his own phone. "Thirteen point eight billion. Plus or minus." He squinted. "Plus or minus about twenty million."

"So the universe could really be thirteen point eight two. Or thirteen point seven eight."

"Right."

"And the star could really be thirteen point six six. Because of the eight hundred million you take away."

Soren stopped.

He looked at his phone. He looked at the old book. He looked at Maya.

"Say that part again," he said. It was the thing he said when something was happening and he wanted to be sure.

"The star says fourteen point four six," Maya said. She was talking with her hands now. "But it's wearing a plus-or-minus of eight hundred million. So it isn't really fourteen point four six. It's somewhere in there. It could be as young as thirteen point six."

"Which is younger than the universe."

"Which is younger than the universe." She grinned. "They don't disagree. They just barely touch."

Soren pulled his notebook out of his bag. He drew two lines on the page, one above the other, and put little bars on the ends of each one. The bars on the bottom line and the bars on the top line reached toward each other until they overlapped, just at the tips.

"It's not a number against a number," he said. "It's a fence against a fence. And the fences are leaning into each other."

"So the book wasn't lying," Maya said. "It just dropped the tail. It printed the middle of the guess and left off the part that says how unsure we are."

Soren tapped the old page. "That's the part that mattered, though. The unsure part is doing all the work."

They sat with that.

"Okay but," Maya said, and Soren knew that but, "why is anybody unsure by eight hundred million years? That's a long time to be wrong by."

Soren read down the screen, his finger moving. "It says how old the star is depends on how far away it is. And how much oxygen it has. And they had to measure the distance again with a space telescope, and the new distance changed the age."

"So the star didn't get younger." Maya said it carefully. "We got better at looking."

"The star's been the same the whole time," Soren said. "The number moved. We moved it."

Maya lay back down on the floor and stared at the water stain on the library ceiling like it was the sky.

"So somewhere out there," she said, "there's a real star, and it has one real age, an actual exact age down to the day it lit up. And nobody knows it. Not one person. We've got a fence around it and we keep making the fence smaller."

"And the fence still includes too old to exist," Soren said. "It hasn't ruled that out yet. The edge of the fence still touches impossible."

Maya turned her head toward him.

"What if it never lets go of it," she said. "What if we measure it a hundred more times and the fence keeps just barely touching the line, forever."

Soren didn't answer right away. He looked at his two leaning lines, the bars almost kissing.

"Then the universe has a star in it," he said, "that we can't prove is allowed."

"That's the best sentence anyone's ever said in this library."

"It's a real star." Soren wrote the distance number under his drawing, the one from the space telescope. "You could point a telescope at it tonight. It's in Libra. It's not even that faint."

Maya sat straight up.

"It's up right now?"

"It's up most of the spring."

She was already on her feet, already halfway to the window at the end of the stacks, the one that faced east over the parking lot where it was going gray-blue toward evening.

The librarian said the library closed in ten minutes.

Maya stood at the glass with her hands cupped around her eyes against the reflection, looking out at a sky that wasn't dark enough yet, at a spot above the streetlights where a star she couldn't see was burning at an age nobody on Earth could pin down, older maybe than the room it was burning in.