"I heard what you said, Hugh. You convinced them."
He nodded. "I wonder why it took me so long to think of it."
The voices died away behind them. They were all alone. They rounded a corner where a viewscreen picked up the image of the moon, so familiar, now the only thing that was familiar about this Earth. Nora shivered.
"You were very logical, Hugh. But I didn't believe you."
He glanced around and saw that there was no one near them and that the communicators in this part of the ship were turned off. Only then did he answer her.
"I didn't believe myself, Nora."
"When we're outside."
They went down the winding ramp that led to the interior of the ship. It too was deserted now. They left the carpeted, muffled corridors and their footsteps rang on the steel plates that lay down the middle of the ship, its heart, where the energy converters were, and the disposal units, and the plant rooms, and the great glass spheres of the hydroponics tanks.
"It's ironic, isn't it?" Nora said slowly. "We left here so long ago, looking for worlds with life, and we come back to find our own world dead."
"It's ironic, all right." He walked along the row of tanks until he came to the one he was searching for, and then he picked up a glass cylinder and filled it from the tank.
"I had to tell them something, Nora. They couldn't have gone on, otherwise."
The bottle was full. He stoppered it and then turned away. They crossed to the nearest lock and he pushed the button that opened it. They waited a few minutes until the door came open, and then they went out, down the ramp to the ground, across the slippery rocks. Even through the clouds there was enough light to see by.
"It's warm," she said.
"It always is, now."
They were approaching the ocean. The surf beat loudly in their ears. The spray was warm against their faces, almost as warm as the night wind.
"Tell me," she said. "You know what really happened, don't you?"
"I think so. I can't really be sure."
They paused on the low ledge where he had stood earlier and watched the girls gather their data for the reports. At their feet the waves washed up to the edges of the tide pools, eddying into and out of them softly. The water looked dark and cold, but they knew that it too was warm.
"There've been lots of changes, and they all fit a pattern," he said. "The temperature. The difference in salt content in the water. The higher tides. Those things could happen for several reasons. But there's only one explanation for the other changes, the ones I found on the star charts."
She waited. The water lapped in and out, reaching almost to where they stood.
"The Earth rotates faster now," he said. "And the stars are nearer. Much nearer than they were."
"Isn't that impossible?"
"How do we know? We exceeded the speed of light. Who could say what continuum that might have put us in? I remember an analogy I read once, in a layman's book on different theories of space-time. '--The future and the past, two branches of a hyperbola, each with the speed of light as its limit--'"
"You mean," she whispered, "that we're not in the future at all? We're in the past--the far past--before there was any life on Earth?"
He looked down at the pools of water at their feet, the lifeless water that according to all their old discarded theories should have been teeming with life. He nodded slowly and lifted the glass cylinder he had brought from the ship and stared at it.
"That bottle," she whispered. "You filled it with bacteria, didn't you?"
He nodded again.
"You're mad, Hugh. You can't mean that that bottle is the origin of life on Earth! You can't."
"Maybe this isn't our Earth, Nora. Maybe there are thousands of continuums and thousands of Earths, all waiting for a ship to land someday and give them life."
Slowly he unstoppered the cylinder and knelt down at the water's edge. For a minute he paused, wondering if there were other continuums or only this one, wondering just how deep the paradox lay. Then he tipped the bottle up and poured, and the liquid from the cylinder ran down into the tide pools and eddied there and was lost in the liquid of the ocean. He poured until the bottle was empty and all the single-celled bacteria from the ship's tank mingled with the warm, lifeless waters.
The water temperatures were the same. Everything was the same, and the conditions were very favorable and the bacteria would divide and redivide and keep on dividing for millions of years.
"We'll hold the ship under light speed," he said. "And in a few million years we can drop back here and see how evolution is getting along."
He stood up and she took his hand and moved closer to him. They were both shivering, despite the warmth of the air.
"But how did life originate in the beginning?" she asked suddenly.
Hugh McCann shook his head in the darkness. "I don't know. We've been all over the galaxy and haven't found life anywhere. Perhaps it can't have a natural cause. Perhaps it's always planted. A closed circle from beginning to end."
"But something--someone--must have started the circle. Who?"
He looked down at the empty cylinder that he had dropped at the water's edge and then he looked out at the ocean, lifeless no longer. And once again he shook his head.
"We did, Nora. We're the beginning."
For a long moment their eyes met and held, and then they turned and walked away from the ocean, back toward the ship, and the people. And the moonlight glinted off the empty bottle.