“Fact. You can look it up.”
Ross shrugged. “That’s no better than the radar data,” he said correctly. “But to get on with my proof. Granted that there is a front side to the moon, whatever it’s nature, just as long as it isn’t so insubstantial that it won’t even reflect radar, then there has to be some sort of a back, flat, round, square, or wiggly. That’s a matter of certain mathematical deduction.”
Morrie snorted.
Cargraves limited himself to a slight smile. “Now, Ross. Think it over. What is the content of mathematics?”
“The content of mathe-” He collapsed suddenly. “Oh.”
“I guess I finally get it. Mathematics doesn’t have any content. If we found there wasn’t any other side, then we would just have to invent a new mathematics.”
“That’s the idea. Fact of the matter is, we won’t know that there is another side to the moon until we get there. I was just trying to show you,” he went on, “just how insubstantial a `common sense’ idea can be when you pin it down. Neither `common sense’ nor `logic’ can prove anything. Proof comes from experiment, or to put it another way, from experience, and from nothing else. Short lecture on the scientific method — you can count it as thirty minutes on today’s study time. Anybody else want breakfast but me? Or has the low weight made you queasy?” He started to climb out of his chair.
Ross was very thoughtful while they made preparations for breakfast. This was to be a proper meal, prepared from their limited supply of non-canned foods. The Galileo had been fitted with a galley of sorts, principally a hot plate and a small refrigerator. Dishes and knives, forks, and spoons could be washed, sparingly, with the water which accumulated in the dump of the air-conditioner, and then sterilized on the hot plate. The ship had everything necessary to life, even a cramped but indispensable washroom. But every auxiliary article, such as dishes, was made of zinc-reserve mass for the hungry jet.
They sat, or rather squatted, down to a meal of real milk, cereal, boiled eggs, rolls, jam, and coffee. Cargraves sighed contentedly when it had been tucked away. “We won’t get many like that,” he commented, as he filled his pipe. “Space travel isn’t all it’s cracked up to be, not yet.”
“Mind the pipe, Skipper!” Morrie warned.
Cargraves looked startled. “I forgot,” he admitted guiltily. He stared longingly at the pipe. “Say, Ross,” he inquired, “do you think the air-conditioner would clean it out fast enough?”
“Go ahead. Try it,” Ross urged him. “One pipeful won’t kill us. But say, Doc-”
“Yes?”
“Well, uh, look — don’t you really believe there is another side to the moon?”
“Huh? Still on that, eh? Of course I do.”
“But it’s just my opinion. I believe it because all my assumptions, beliefs, prejudices, theories, superstitions, and so forth, tend that way. It’s part of the pattern of fictions I live by, but that doesn’t prove it’s right. So if it turns out to be wrong I hope I am sufficiently emotionally braced not to blow my top.”
“Which brings us right back to study time,” he went on. “You’ve all got thirty minutes credit, which gives you an hour and a half to go. Better get busy.”
Art looked dumfounded. “I thought you were kidding Uncle. You don’t mean to run such a schedule on the moon, do you?”
“Unless circumstances prevent. Now is a good time to work up a little reserve, for that matter, while there is nothing to see and no work to do.”
Art continued to look astonished, then his race cleared. “I m afraid we can’t, Uncle. The books are all packed down so far that we can’t get at them till we land.”
“So? Well, we won’t let that stop us. A school,” he quoted, “is a log with a pupil on one end and a teacher on the other. We’ll have lectures and quizzes — starting with a review quiz. Gather round, victims.”
They did so, sitting cross-legged in a circle on the hold bulkhead. Cargraves produced a pencil and a reasonably clean piece of paper from his always bulging pockets. “You first, Art. Sketch and describe a cyclotron. Basic review — let’s see how much you’ve forgotten.”