The Stretch

The rope bridge over the creek was sixteen tiles long. Maya knew because she had counted the wooden slats twice. Soren measured it with a tape, and his number came out different.

Sixteen point two meters, he said. Then he walked back and measured again. Sixteen point one.

Maya frowned. It can't be two things.

It isn't, said Soren. The bridge moves. When the wind pushes it, the slats spread. The distance changes.

They stood on the bank and watched the bridge breathe in the wind, the gaps between slats opening and closing like the bridge was made of slow lungs. Maya liked this. Something everyone walked across without thinking, and the length of it was never quite settled.

Later they were lying on the warm flat rock where the creek widened, looking up. A plane crossed without a sound, then the sound caught up to it a beat behind, low and torn.

Soren said the thing he had been carrying around all week. In space there's no sound at all. A star can explode and you'd hear nothing. There's no air to push.

Maya knew this already. But knowing it and feeling it were different, and lying on the rock she felt it for the first time, a silence so complete it had a shape. Every enormous thing out there, every collision, happening with no noise, forever.

That's lonely, she said.

Soren turned his notebook over on his chest. He had read something and it had not let go of him. But there's another way to feel something far away, he said. Not sound. The distance itself moves.

Maya sat up. Like the bridge.

Kind of. He chose his words slowly because he wanted to get it right and he knew he might not. When two black holes spin into each other, they shake space. Not the stuff in space. Space. The thing distance is made of. It sends out a ripple, and when the ripple goes through you, you get a little taller and then a little shorter.

Maya looked at her own hands. You're saying I stretch.

Everyone stretches. The whole creek. The bridge. Me. The ripple passes through and for a tiny moment the distance from your head to your feet is longer, then shorter.

Then I'd feel it, said Maya.

No. That's the part that's hard. Soren sat up too. He flipped to a page where he had copied a number, and he was almost embarrassed by it. The stretch is smaller than an atom. Smaller than a piece of an atom. If you measured a distance as long as from here to the next star, the ripple would change it by less than the width of a hair.

Maya was quiet. This was the kind of quiet Soren had learned to wait through, because something was assembling behind it.

Then how does anyone know, she said. If it's smaller than everything. How do you measure a change you can't feel and can't see and that moves the ruler too.

That was the trap and Soren had fallen into it himself reading the article. If space stretches, then your ruler stretches with it. Measure the bridge while the bridge and the tape both grow, and the number never changes.

They sat with that. The creek went over the stones. Somewhere upstream a frog dropped in.

Maya picked up two pebbles. She set one on the rock by her left hand and one by her right, far apart, and she looked from one to the other, back and forth, the way you look at two things you're comparing.

Light, she said.

Soren waited.

You said it stretches distance. She was talking faster now, the way she did when the answer was arriving before she could explain it. You can't trust a ruler made of stuff because the stuff stretches too. But light always goes the same speed. So you send light across the distance and time how long the trip takes. If the distance gets longer, the light takes longer. If it gets shorter, the light comes back sooner. The light doesn't lie.

Soren stared at her. Then he looked down at his notebook, at the word he had copied and not understood, the word interferometer, and the picture of an L-shaped machine with two arms four kilometers long.

That's it, he said quietly. That's actually it. They send light down two long arms at right angles. When the ripple comes, one arm stretches and the other squeezes, just for an instant, and the light in the two arms falls out of step. He looked up at her. You figured out the machine. They built a real one. It's exactly what you said.

Maya did not look proud. She looked like someone who had walked into a room she hadn't known was there.

So it worked, she said. They heard one.

Not heard. There's no sound. Soren stopped. But also. He turned the idea over. They turned the stretch into a sound afterward. Played it through a speaker so people could listen. It was a chirp. Two black holes a billion years away, falling together, and a billion years later the ripple reaches a machine in a desert and it goes chirp.

A billion years, said Maya.

The thing that made it doesn't exist anymore. It crashed into one black hole before there was anything on Earth that could wonder about it. The ripple was just traveling. The whole time. Coming.

Maya looked at the rope bridge breathing in the wind, sixteen point one, sixteen point two, the gaps opening and closing. Then she looked at the space above it, the silent enormous everything, and it did not feel lonely anymore. It felt like it was touching her. Slowly. Constantly. A little taller, a little shorter, the whole creek and both of them rising and falling under ripples too small to feel, from collisions too far to imagine, that had been on their way since before the rock she sat on was a rock.

We're being stretched right now, she said. By something that already died.

Probably, said Soren. Faintly. All the time.

Maya lay back down on the warm rock and spread her arms out wide, one pebble in each hand, holding the distance between her own two hands as open as she could make it.