alien life. But now we’ve got the problem of communicating with it.”
Crandall didn’t appear to notice my stiff reply. He said, “Confound it, what’s missing?”
“What’s missing,” I told him, “is some common point of reference.”
“Meaning?”
“Meaning that I could define left from right to any semi-intelligent human being who was aware of the environment in which we live.”
“For example?”
I groped for an example and said, lamely, “Well, there’s the weather rule, valid for the northern hemisphere. When the wind is blowing on your back, the left hand points to the low pressure center.”
“Okay. But how about Venus? Astronomical information, I mean.”
I shook my head.
“Why not?” he demanded. “If we face north, the sun rises on our right, doesn’t it?”
“Yes. Even in the southern hemisphere.”
“Well, then. So it doesn’t make any difference which hemisphere they’re in.”
“You’re correct. But you’re also making the assumptions that Venus rotates on its axis, that the axis is aligned parallel to the Earth’s and that the direction of rotation is the same.”
“We know that Venus rotates!”
“We have every reason to believe so,” I agreed. “But only because thermocouples measure a temperature on the darkside that is too high to support the theory that the diurnal period of Venus is equal to the year. I think the latest figures say something between a couple of weeks and a few months. Next, the axis needn’t be parallel to anything. Shucks, Crandall, you know darned well that the solar system is a finely made clock with no two shafts aligned, and elliptical gears that change speed as they turn.”
*
“Practically everything in the solar system rotates in the same direction.”
I looked at him. “Would you like to take a chance that Venus agrees with that statement? You’ve got a fifty percent chance that you’ll be right. Guess wrong and we have a metric ton of hardware trying to occupy the same space as another metric ton of matter.”
“But—”
“And furthermore,” I went on, “we’re just lucky that Polaris happens to be a pole star right now. The poles of Mars point to nothing that bright. Even then, we can hardly expect the Venusian to have divided the circumpolar sky into the same zoo full of mythical animals as our forebears—and if we use the commonplace expression, maybe the Venusian never paused to take a long-handled dipper of water from a well. Call them stewpots and the term is still insular. Sure, there’s lots of pointers, but they have to be identified. My mother always insisted that the Pleiades were—er—was the Little Dipper.”
Teresa Dwight spoke up, possibly for the second or third time in her life without being spoken to first. She said, “Harla has been listening to you through me. Of astronomy he has but a rudimentary idea. He is gratified to learn from you that there is a ‘sun’ that provides the heat and light. This has been a theory based upon common sense; something had to do it. But the light comes and goes so slowly that it is difficult to determine which direction the sun rises from. The existence of other celestial bodies than Venus is also based on logic. If, they claim, they exist, and their planet exists, then there probably are other planets with people who cannot see them, either.”
“Quoth Pliny the Elder,” mumbled Paul Wallach.
I looked at him.
“Pliny was lecturing about Pythagoras’ theory that the Earth is round. A heckler asked him why the people on the other side didn’t fall off. Pliny replied that on the other side there were undoubtedly fools who were asking their wise men why we didn’t fall off.”
“It’s hardly germane,” I said.
“I’m sorry. Yes. And time is running out.”
*
The laboratory door opened to admit a newcomer, Lou Graham, head of the electronics crew.
He said, “I’ve got it!”
The chattering noise level died out about three decibels at a time. Lou said, “When a steel magnet is etched in acid, the north pole shows selective etching!”
I shook my head. “Lou,” I said, “we don’t know whether Venus has a magnetic field, whether it is aligned to agree with the Earth’s—nor even whether the Venusians have discovered the magnetic compass.”
“Oh, that isn’t the reference point,” said Lou Graham. “I’m quite aware of the ambiguity. The magnetic field does have a vector, but the arrow that goes on the end is strictly from human agreement.”
“So how do you tell which is the north pole?”
“By making an electromagnet! Then using Ampere’s Right Hand Rule. You grasp the electromagnet in the right hand so that the fingers point along the winding in the direction of the current flow. The thumb then points to the north pole.”
“Oh, fine! Isn’t that just the same confounded problem? Now we’ve got to find out whether Harla is equipped with a right hand complete with fingers and thumbs—so that we can tell him which his right hand is!”
“No, no,” he said. “You don’t understand, Tom. We don’t need the right hand. Let’s wind our electromagnet like this: We place the steel bar horizontally in front of us. The wire from ‘Start’ leaves us, passes over the top of the bar, drops below the bar on the far side, comes toward us on the under side, rises above the bar on the side toward us, and so on around and around until we’ve got our electromagnet wound. Now if the ‘start’ is positive and the ‘end’ is negative, the north pole will be at the left. It will show the selective etching in acid.”
I looked at him. “Lou,” I said slowly, “if you can define positive and negative in un-ambiguous terms as well as you wound that electromagnet, we can get Holly home. Can you?”
Lou turned to Teresa Dwight. “Has this Harla fellow followed me so far?”
She nodded.
“Can you speak for him?”
“You talk, I hear, he reads me. I read him and I can speak.”
*
“Okay, then,” said Lou Graham. “Now we build a Le Clanche cell. Ask Harla does he recognize carbon. A black or light-absorbing element. Carbon is extremely common, it is the basis of life chemistry. It is element number six in the periodic chart. Does Harla know carbon?”
“Harla knows carbon.”
“Now we add zinc. Zinc is a light metal easily extracted from the ore. It is fairly abundant, and it is used by early civilizations for making brass or bronze long before the culture has advanced enough to recognize zinc as an element. Does Harla know zinc?”
“He
