Contact - Carl Sagan [74]
"Well, in terms of stellar properties, anything like that, I can't think of a thing. But there is one incidental fact: Vega was the Pole Star about twelve thousand years ago, and it will be again about fourteen thousand years from now."
"I though the polestar was the Pole Star." Rankin, still doodling, said this to the pad of paper.
"It is, for a few thousand years. But not forever. The Earth is like a spinning top. Its axis is slowly precessing in a circle." She demonstrated, using her pencil as the Earth's axis. "It's called the precession of the equinoxes."
"Discovered by Hipparchus of Rhodes," added Joss. "Second century B.C." This seemed a surprising piece of information for him to have at his fingertips.
"Exactly. So right now," she continued, "an arrow from the center of the Earth to the North Pole points to the star we call Polaris, in the constellation of the Little Dipper, or the Little Bear. I believe you were referring to this constellation just before lunch, Mr. Rankin. As the Earth's axis slowly precesses, it points in some different direction in the sky, not toward Polaris, and over 26,000 years the place in the sky to which the North Pole points makes a complete circle. The North Pole points right now very near Polaris, close enough to be useful in navigation. Twelve thousand years ago, by accident, it pointed to Vega. But there's no physical connection. How the stars are distributed in the Milky Way has nothing to do with the Earth's axis of rotation being tipped twenty-three and a half degrees."
"Now, twelve thousand years ago is 10,000 B.C., the time when civilization was just starting up. Isn't that right?" Joss asked.
"Unless you believe that the Earth was created in 4004 B.C."
"No, we don't believe that, do we, Brother Rankin? We just don't think the age of the Earth is known with the same precision that you scientists do. On the question of the age of the Earth, we're what you might call agnostics." He had a most attractive smile.
"So if folks were navigating ten thousand years ago, sailing the Mediterranean, say, or the Persian Gulf, Vega would have been their guide?"
That's still in the last Ice Age. Probably a little early for navigation. But the hunters who crossed the Bering land bridge to North America were around then. I must have seemed an amazing gift- providential, if you like-that such a bright star was exactly to the north. I'll bet a lot of people owed their lives to that coincidence."
"Well now, that's mighty interesting."
"I don't want you to think I used the word `providential' as anything but a metaphor."
"I'd never think that, my dear."
Joss was by now giving signs that the afternoon was drawing to a close, and he did not seem displeased. But there were still a few items, it seemed, on Rankin's agenda.
"It amazes me that you don't think it was Divine Providence, Vega being the Pole Star. My faith is so strong I don't need proofs, but every time a new fact comes along it simply confirms my faith."
"Well then, I guess you weren't listening very closely to what I was saying this morning. I resent the idea that we're in some kind of faith contest, and you're the hands-down winner. So far as I know you've never tested your faith? I'm willing to do it for mine. Here, take a look out that window. There's a big Foucault pendulum out there. The bob must weight five hundred pounds. My faith says that the amplitude of a free pendulum-how far it'll swing away from the vertical position-can never increase. It can only decrease. I'm willing to go out there, put the bob I front of my nose, let go, have it swing away and then back toward me. If my beliefs are in error, I'll get a five-hundred-pound pendulum smack in the face. Come on. You want to test my faith?"
"Truly, it's not necessary. I believe you," replied Joss. Rankin, though, seemed interested. He was imagining, she guessed, what she would look like afterward.
"But would you be willing,"