Foundation and Earth

"Then we'll try something else."

"Like what?" "I wish I knew," said Trevize grimly.

Part Three Aurora

Chapter 8 Forbidden World

31.

"GOLAN," said Pelorat. "Does it bother you if I watch?"

"Not at all, Janov," said Trevize.

"If I ask questions?"

"Go ahead."

Pelorat said, "What are you doing?"

Trevize took his eyes off the viewscreen. "I've got to measure the distance of each star that seems to be near the Forbidden World on the screen, so that I can determine how near they really are. Their gravitational fields must be known and for that I need mass and distance. Without that knowledge, one can't be sure of a clean Jump."

"How do you do that?"

"Well, each star I see has its co-ordinates in the computer's memory bank and these can be converted into co-ordinates on the Comporellian system. That can, in turn, be slightly corrected for the actual position of the Far Star in space relative to Comporellon's sun, and that gives me the distance of each. Those red dwarfs all look quite near the Forbidden World on the screen, but some might be much closer and some much farther. We need their three-dimensional position, you see."

Pelorat nodded, and said, "And you already have the co-ordinates of the Forbidden World-"

"Yes, but that's not enough. I need the distances of the other stars to within a percent or so. Their gravitational intensity in the neighborhood of the Forbidden World is so small that a slight error makes no perceptible difference. The sun about which the Forbidden World revolves-or might revolve-possesses an enormously intense gravitational field in the neighborhood of the Forbidden World and I must know its distance with perhaps a thousand times the accuracy of that of the other stars. The co-ordinates alone won't do."

"Then what do you do?"

"I measure the apparent separation of the Forbidden World-or, rather, its star-from three nearby stars which are so dim it takes considerable magnification to make them out at all. Presumably, those three are very far away. We then keep one of those three stars centered on the screen and Jump a tenth of a parsec in a direction at right angles to the line of vision to the Forbidden World. We can do that safely enough even without knowing distances to comparatively far-off stars.

"The reference star which is centered would still be centered after the Jump. The two other dim stars, if all three are truly very distant, do not change their positions measurably. The Forbidden World, however, is close enough to change its apparent position in parallactic shift. From the size of the shift, we can determine its distance. If I want to make doubly certain, I choose three other stars and try again."

Pelorat said, "How long does all that take?"

"Not very long. The computer does the heavy work. I just tell it what to do. What really takes the time is that I have to study the results and make sure they look right and that my instructions aren't at fault somehow. If I were one of those daredevils with utter faith in themselves and the computer, it could all be done in a few minutes."

Pelorat said, "It's really astonishing. Think how much the computer does for us."

"I think of it all the time."

"What would you do without it?"

"What would I do without a gravitic ship? What would I do without my astronautic training? What would I do without twenty thousand years of hyperspatial technology behind me? The fact is that I'm myself-here-now. Suppose we were to imagine ourselves twenty thousand additional years into the future. What technological marvels would we have to be grateful for? Or might it be that twenty thousand years hence humanity would not exist?"

"Scarcely that," said Pelorat. "Scarcely not exist. Even if we don't become part of Galaxia, we would still have psychohistory to guide us."

Trevize turned in his chair, releasing his handhold on the computer. "Let it work out distances," he said, "and let it check the matter a number of times. There's no hurry."

He looked quizzically at Pelorat, and said, "Psychohistory! You know, Janov, twice that subject came up on Comporellon, and twice it was described as a superstition. I said so once, and then Deniador said it also. After all, how can you define psychohistory but as a superstition of the Foundation? Isn't it a belief without proof or evidence? What do you think, Janov? It's more your field than mine."

Pelorat said, "Why do you say there's no evidence, Golan? The simulacrum of Hari Seldon has appeared in the Time Vault many times and has discussed events as they happened. He could not have known what those events would be, in his time, had he not been able to predict them psychohistorically."

Trevize nodded. "That sounds impressive. He was wrong about the Mule, but even allowing for that, it's impressive. Still, it has an uncomfortable magical feel to it. Any conjurer can do tricks."

"No conjurer could predict centuries into the future."

"No conjurer could really do what he makes you think he does."