Free Nightfall by Isaac Asimov, Robert Silverberg Page B

constructed out of approximations that gradually approach the truth, you told me a long time back, and I’ve never forgotten it. Well, that means all theories are subject to constant testing and modification, doesn’t it? And if it eventually turns out that they’re not quite close enough to the truth, they need to be replaced by something that’s closer. Right, Beenay? Right?”
    Beenay was trembling now. He looked very pale.
    “Could you get me another drink, Theremon?”
    “No. Listen to me: there’s more. You say that you’re so worried about Athor—he’s old; I suppose he’s pretty frail—that you don’t have the heart to tell him you’ve found a flaw in his theory. All right. That’s a decent and loving position to take. But think about this, will you? If calculating the orbit of Kalgash is all that important, somebody else is likely to stumble across the same flaw in Athor’s theory sooner or later, and that other person isn’t likely to be as tactful in letting Athor knowabout it as you’d be. He might even be a professional rival of Athor’s, an outright enemy of his—every scientist has enemies, you’ve told me so plenty of times. Wouldn’t it be better for you to go to Athor and tell him, gently, carefully, of what you’ve discovered, than for him to find out about it one morning in the
Chronicle
?”
    “Yes,” Beenay whispered. “You’re completely right.”
    “You’ll go to him, then?”
    “Yes. Yes. I have to, I suppose.” Beenay bit his lip. “I feel miserable about this, Theremon. I feel like a murderer.”
    “I know you do. But it isn’t Athor you’ll be murdering, it’s a defective theory. Defective theories must never be allowed to persist. You owe it to Athor as well as yourself to let the truth emerge.” Theremon hesitated. A sudden startling new idea had occurred to him. “Of course, there’s one other possibility. I’m only a layman, you know, and you’ll probably laugh. —Is there any chance that the Theory of Gravitation might be correct despite everything, and that the computer’s figures for Kalgash’s orbit are right also, and that some other factor entirely, something altogether unknown, might be responsible for the discrepancy in your result?”
    “That could be, I suppose,” said Beenay in a flat, dispirited tone. “But once you begin dragging in mysterious unknown factors, you begin to move into the realm of fantasy. —I’ll give you an example. Let’s say there’s an invisible seventh sun out there—it’s got mass, it exerts gravitational force, but we simply can’t see it. Since we don’t know it’s there, we haven’t plugged it into our gravitational calculations, and so the figures come out cockeyed. Is that what you mean?”
    “Well, why not?”
    “Why not
five
invisible suns, then? Why not fifty? Why not an invisible giant who pushes planets around according to his whims? Why not a huge dragon whose breath deflects Kalgash from its proper path? We can’t disprove it, can we? When you start in with
why nots
, Theremon, anything becomes possible, and then nothing makes any sense. At least not to me. I can only deal with what I know is real. You may be right that there’s an unknown factor, and that therefore the gravitational laws aren’t invalid. I certainly hope so. But I can’t do serious work on that basis. All I can do is go to Athor, which I will, Ipromise you that, and tell him what the computer has told me. I don’t dare suggest to him or anybody that I blame the whole mess on a hitherto undiscovered ‘unknown factor.’ Otherwise I’d sound just as crazy as the Apostles of Flame, who claim to know all sorts of mystic revelations. —Theremon, I really want that other drink now.”
    “Yes. All right. And speaking of the Apostles of Flame—”
    “You want a statement from me, I remember.” Beenay passed a hand wearily in front of his face. “Yes. Yes. I won’t let you down. You’ve been a tremendous help to me