The Blue That Shouldn't Be There

The pool was forty feet deep and the water was so clear it looked like nothing at all. That was the first strange thing. Maya leaned over the railing and could see the racks at the bottom, gray metal shapes stacked in rows, sharp-edged, close enough to touch and impossibly far away.

Then she noticed the blue.

It was not the blue of the tiled walls. It was not a reflection. It hung in the water around the racks like a color that had been poured in and refused to mix, a blue so clean it made her teeth feel cold to look at.

"Soren," she said. "Where's that coming from?"

Soren put both hands on the rail and looked. He was quiet for a moment, and then he did the thing he always did, which was to look for the lamp. There was no lamp. The gallery lights above them were ordinary and yellow. The blue was underneath the water, and it did not flicker, and it did not come from any bulb.

"There's no light down there," he said. "Nothing's turned on."

A guide stood near the door, a woman with a lanyard and a coffee cup, only half watching them. "Beautiful, isn't it," she said, in the flat voice of someone who has said it forty times today. "That's the fuel. It's safe. The water shields you."

"But what makes the color," Soren asked.

"Radiation," she said, and sipped her coffee, and looked at her phone.

Maya frowned. Radiation was invisible. Everyone knew that. You couldn't see it. That was the whole scary thing about it, that it was there and you couldn't see it. So the blue could not just be radiation. The blue was something the radiation was doing.

"It's not the radiation we're seeing," she said slowly. "It's what the radiation bumps into."

Soren looked at her. "What made you think that?"

"Because you can't see the thing itself. So you're seeing a splash." She spread her fingers over the rail. "Like when you drop a stone in a puddle. You don't see the stone hit. You see the rings go out."

Soren pulled out his notebook and uncapped his pen. He drew a dot, and rings around the dot, and then he stopped and stared at the water some more.

The blue was brightest right at the racks and faded as it climbed. It looked, Maya thought, like it was being left behind. Like a wake. Like the white water a boat drags behind itself.

"It's a wake," she said out loud.

"Boats make wakes because they push the water," Soren said. "Nothing's moving down there."

"Something is, though." She was sure of it before she could say why. "Something's going through the water. Really fast. And it's making a wake out of light."

Soren wrote wake out of light and underlined it and then frowned at his own handwriting like it had said something impossible.

"That doesn't work," he said carefully. "To leave a wake, you have to move faster than the wave you're making. A boat makes a wake because the boat goes faster than the ripples in the water. A jet makes a boom because it goes faster than sound." He tapped the pen. "So to make a wake out of light, something would have to move faster than light."

He stopped.

He said it again, quieter. "Faster than light."

The two of them looked down into forty feet of perfectly clear water, and the blue hung there, patient, not flickering, not caring that it was breaking a rule they had both been told could never be broken.

"Nothing goes faster than light," Maya said. But she said it like a question.

Soren was very still. Then he flipped back a page in his notebook, to something he'd copied out weeks ago and never understood. He read it twice. When he looked up his eyes were bright.

"In a vacuum," he said. "Nothing goes faster than light in a vacuum. That's the rule. That's the actual rule."

"But this isn't a vacuum." Maya's hands had gone tight on the rail. "This is water."

"Light slows down in water." Soren was talking fast now, faster than his pen could keep up, so he stopped writing entirely. "It has to push through all the water. It goes slower. Way slower. And if light is going slower down there than it does in empty space, then something else could be going faster than the light. Not faster than the rule. Faster than the light in the water."

Maya felt the cold-teeth feeling spread down into her stomach, and it was not fear, it was the opposite of fear, it was the feeling of a wall she'd leaned on her whole life turning out to be a door.

"So something's coming off the fuel," she said, "going so fast that even light can't keep up with it. Down there. In the water. And the blue is the wake."

"The blue is the wake," Soren said.

They both leaned out over the water at the same time, shoulders almost touching, and stared at the blue like they were staring at a boat they could not see, tearing across an ocean, outrunning light itself, throwing up glow the way a hull throws up foam. Somewhere down in the clear cold water, particles they would never see were racing ahead of their own shine, and the shine was piling up behind them with nowhere to go, and spilling out sideways, and rising, and reaching the surface as this.

The guide had wandered over. "You two have been staring a long time," she said, not unkindly.

"Something down there is going faster than light," Maya told her.

The guide smiled the way adults smile when they think a child has made a nice mistake. "Nothing goes faster than light, sweetheart."

"In a vacuum," Soren said.

The smile stopped. The guide looked down into the pool, at the blue she had described forty times today, and something moved behind her face, like she was seeing it for the very first time, like she had been standing next to the door her whole life without noticing it was open.

"Huh," she said softly.

Maya wasn't listening anymore. She had put her chin nearly on the rail and closed one eye, tracking the brightest thread of blue as it wavered upward through the water, following the wake of a thing too fast to catch, watching the light it had already left behind climb slowly, slowly, toward the surface, and break there, and disappear into the ordinary yellow air of the room.