Pathfinder (Pathfinder 1)

CHAPTER 8

The Tower

Ram thought about it sitting, standing, walking, lying down. He thought about it with eyes closed and open, playing computer games and reading books and watching films and doing nothing at all.

Finally he thought of a question that might lead to a useful bit of information. “The light of stars behind us—blue or red shifted?”

“By ‘behind us,’ do you mean in the spatial position we occupied moments ago? Or in the direction of the stern of this vessel?”

“Stern of the vessel,” said Ram. “Earthward.”

“Red shift.”

“If we were moving toward Earth, it should be blue-shifted.”

“This is an anomaly,” said the expendable. “We are closer to Earth with the passage of each moment, and yet the shift is red. The computers are having a very hard time coping with the contradictory data.”

“Compare the degree of red shift with the red shift when we were in the same position on our way to the fold.”

The expendable didn’t even pause. It was a simple data lookup, and to a human mind it seemed to take no time at all.

“The red shift is identical to what was recorded on the outbound voyage.”

“Then we are simply repeating the outbound voyage,” said Ram. “The ship is moving forward, as propelled by the drive. But we, inside the ship, are moving backward in time.”

“Then why are we not observing ourselves as we were two days ago on the outbound voyage?” asked the expendable.

“Because that version of ourselves is not moving through time in the same direction as we are,” said Ram.

“You say this as if it made sense.”

“If I started crying and screaming, you’d stop taking me seriously.”

“I’m already not taking you seriously,” said the expendable. “My programming requires that I keep your most recent statements in the pending folder, because they cannot be reconciled with the data.”

“It’s really quite elegant,” said Ram. “The ship is the same ship. Everything about it that does not need to change remains exactly as it was on the outbound voyage. It occupies the same space and the same time. But the flow of electrical data and instructions through the computers and your robot brain and my human one, and our physical motions through space, are not the same, because our causality is moving in a different direction. We are moving through the same space as our earlier selves, but we are not on the same timestream, and therefore we are invisible to each other.”

“This is an impossible explanation,” said the expendable.

“Come up with a better one, then.”

This time the expendable waited a long time. He remained completely still while Ram deliberately and without hunger pushed food into his mouth and chewed it and swallowed it.

“I do not have a better explanation,” said the expendable. “I can only reason from information that has already been reasoned from successfully.”

“Then I suppose that’s why you needed a human being to be awake after the jump,” said Ram.

“Ram,” said the expendable. “What will happen to us when this ship reaches Earth?”

“At some point,” said Ram, “either the two versions of the ship will separate and probably explode, or we will separate from the ship and die in the cold of space, or we will simply reach Earth and continue to live backward until I die of old age.”

“But I am designed to last forever,” said the expendable, “if not interfered with.”

“Isn’t that nice? Expendable yet eternal. You’ll be able to go back and observe any part of human history that you wish. Watch the pyramids being unbuilt. See the ice ages go and come in reverse. Watch the de-extinction of the dinosaurs as a meteor leaps out of the Gulf of Mexico.”

“I will have no useful task. I will not be able to help the human race in any way. My existence will have no meaning after you are dead.”

“Now you know how humans feel all the time.”