Poul Anderson - New America

They mumbled, down in the hall, and stared at him and did not understand. He sucked air into his lungs and tried anew:

“Yes, you don’t intend to harm the Mithrans. Thus far there has been little conflict. But when your numbers grow, when you begin to rape the land for all the resources this hungry civilization needs, when mutual exasperation escalates into battle—can you speak for your children? Your grandchildren? Their grandchildren, to the end of time? The people of Bach and Goethe brought forth Hitler. No, you don’t know what I am talking about, do you?

“Well, let us suppose that man on this planet reverses his entire previous record and gives the natives some fairly decent reservations and does not take them away again. Still, how much hope have they of becoming anything but parasites? They cannot become one with you. The surviving Amerinds could be assimilated, but they were human. Mithrans are not. They do not and cannot think like humans. But don’t they have the right to live in their world as they wish, make their own works, hope their own hopes?

“You call this planet underpopulated. By your standards, that is correct. But not by the natives’. How many individuals per hectare do you expect an economy like theirs to support? Take away part of a continent, and you murder that many unborn sentient beings. But you won’t stop there. You will take the world, and so murder an entire way of existence. How do you know that way isn’t better than ours? Certainly you have no right to deny the universe the chance that it is better.”

They seethed and buzzed at his feet. Thrailkill advanced, fists clenched, and said flatly, “Have you so little pride in being a man?”

“On the contrary,” Kahn answered, “I have so much pride that I will not see my race guilty of the ultimate crime. We are not going to make anyone else pay for our mistakes. We are going home and see if we cannot amend them ourselves.”

“So you say!” Thrailkill spat.

O God of mercy, send my men. Kahn looked into the eyes of the one whose salt he had eaten, and knew they would watch him for what remained of his life. And behind would gleam the Bay of Desire, and the Princess’ peak holy against a smokeless heaven, and the Weatherwomb waiting for ships to sail west. “You will be heroes on Earth,” he said. “And you will at least have memories. I—”

The communicator in his pocket buzzed. “Ready.” He slapped it once: “Go ahead.”

Thunder crashed on the roof, shaking walls. A deeptoned whistle followed. Kahn sagged back against the lectern. That would be the warboat, with guns and nuclear bombs.

The door flew open. Redfeather entered, and a squad of armed men. The rest had surrounded the hall.

Kahn straightened. His voice was a stranger’s, lost in the yells and cries: “You are still citizens of the Directorate. As master of an official ship, I have discretionary police authority. Will or no, you shall come back with me.”

He saw Leonie clutch her child to her. He ducked Thrailkill’s roundhouse swing and stumbled off the stage, along the aisle toward his men. Hands grabbed at him. Redfeather fired a warning burst, and thereafter he walked alone. He breathed hard, but kept his face motionless. It wouldn’t do for him to weep. Not yet.

And so end these chronicles of the folk who took the long road to the stars. And long it is, not at all like those here, nor the highways of other fictional universes. It is unlike them in another way, too. It is a road that is always open. It is real…

There are countless varieties of science fiction these days, and I would be the last to want any of them restricted in any way. Nevertheless, what first drew me to this literature and, after more years than I like to add up, still holds me, is its dealing with the marvels of the universe. To look aloft at the stars on a clear night and think that someday, somehow we might actually get out among them, rouses the thrill anew, and I become young again. After all, we made it to the Moon didn’t we? Mean wile, only science fiction of the old and truly kind takes the imagination forth on that journey. Therefore I put up with its frequent flaws; and so does many another dreamer.

But are we mere dreamers, telling ourselves stories of voyages yonder as our ancestors told of voyages to Avalon and Cibola? Those never existed, and the stars do; but, realistically, does any possibility of reaching them?

The case against interstellar travel traditionally begins with the sheer distances. While Pioneer 10 and 11, the Jupiter flybys, will leave the Solar System, they won’t get as far as Alpha Centauri, the nearest neighbor sun, for more than 40,000 years. (They aren’t actually bound in that direction.) At five times their speed, or 100 miles per second, which we are nowhere close to reaching today, the trip would take longer than recorded history goes back. And the average separation of stars in this galactic vicinity is twice as great.

If we could go very much faster—

At almost the speed of light, we’d reach Alpha Centauri in about four and a third years. But as most of you know, we who were faring would experience a shorter journey. Both the theory of relativity and experimental physics show that time passes “faster” for a fast-moving object. The closer the speed of light, the greater the difference, until at that velocity itself, a spaceman would make the trip in no time at all. However, the girl he left behind him would measure his transit as taking the same number of years as a light ray does; and he’d take equally long in coming back to her.

In reality, the velocity of light in vacuo , usually symbolized by c, cannot be attained by any material body. From a physical viewpoint, the reason lies in Einstein’s famous equation E = mc 2. Mass and energy are equivalent. The faster a body moves, the more energy it has, and hence the more mass. This rises steeply as velocity gets close to c, and at that speed would become infinite, an obvious impossibility.

Mass increases by the same factor as time (and length) shrink. An appendix to this essay defines the terms more precisely than here. A table there gives some representative values of the factor for different values of velocity, v compared to c. At v = 7c, that is, at a speed of 70% light’s, time aboard ship equals distance covered in light-years. Thus, a journey of 10 light-years at 0.7c would occupy 10 years of the crew’s lives, although to people on Earth or on the target planet, it would take about 14.

There’s a catch here. We have quietly been supposing that the whole voyage is made at exactly this rate. In practice, the ship would have to get up to speed first, and brake as it neared the goal. Both these maneuvers take time; and most of this time is spent at low velocities where the relativistic effects aren’t noticeable.

Let’s imagine that we accelerate at one gravity, increasing our speed by 32 feet per second each second and thus providing ourselves with a comfortable Earth-normal weight inboard. It will take us approximately a year (a shade less) to come near c, during which period we will have covered almost half a light-year, and during most of which period our time rate won’t be significantly different from that of the outside cosmos. In fact, not until the eleventh month would the factor get as low as 0.5, though from then on it would start a really steepening nosedive. Similar considerations apply at journey’s end, while we slow down. Therefore a trip under these conditions would never take less than two years as far as we are concerned; if the distance covered is 10 light-years, the time required is 11 years as far as the girl (or boy) friend left behind is concerned.