Tau Zero

Nevertheless, such spaces could be conquered. A ship accelerating continuously at one gravity would have traveled half a light-year in slightly less than one year of time. And she would be moving very near the ultimate velocity, three hundred thousand kilometers per second.

Practical problems arose. Where was the mass-energy to do this coming from? Even in a Newtonian universe, the thought of a rocket, carrying that much fuel along from the start, would be ludicrous. Still more so was it in the true, Einsteinian cosmos, where the mass of ship and payload increased with speed, climbing toward infinity as that speed approached light’s.

But fuel and reaction mass were there in space! It was pervaded with hydrogen. Granted, the concentration was not great by terrestrial standards: about one atom per cubic centimeter in the galactic vicinity of Sol. Nevertheless, this made thirty billion atoms per second, striking every square centimeter of the ship’s cross section, when she approximated light velocity. (The figure was comparable at earlier stages of her voyage, since the interstellar medium was denser close to a star.) The energies were appalling. Megaroentgens of hard radiation would be released by impact; and less than a thousand r within an hour are fatal. No material shielding would help. Even supposing it impossibly thick to start with, it would soon be eroded away.

However, in the days of Leonora Christine non-material means were available: magnetohydrodynamic fields, whose pulses reached forth across millions of kilometers to seize atoms by their dipoles — no need for ionization — and control their streaming. These fields did not serve passively, as mere armor. They deflected dust, yes, and all gases except the dominant hydrogen. But this latter was forced aft — in long curves that avoided the hull by a safe margin — until it entered a vortex of compressing, kindling electromagnetism centered on the Bussard engine.

The ship was not small. Yet she was the barest glint of metal in that vast web of forces which surrounded her. She herself no longer generated them. She had initiated the process when she attained minimum ramjet speed; but it became too huge, too swift, until it could only be created and sustained by itself. The primary thermonuclear reactors (a separate system would be used to decelerate), the venturi tubes, the entire complex which thrust her was not contained inboard. Most of it was not material at all, but a resultant of cosmic-scale vectors. The ship’s control devices, under computer direction, were not remotely analogous to autopilots. They were like catalysts which, judiciously used, could affect the course of those monstrous reactions, could build them up, in time slow them down and snuff them out … but not fast.

Starlike burned the hydrogen fusion, aft of the Bussard module that focused the electromagnetism which contained it. A titanic gas-laser effect aimed photons themselves in a beam whose reaction pushed the ship forward — and which would have vaporized any solid body it struck. The process was not 100 per cent efficient. But most of the stray energy went to ionize the hydrogen which escaped nuclear combustion. These protons and electrons, together with the fusion products, were also hurled backward by the force fields, a gale of plasma adding its own increment of momentum.

The process was not steady. Rather, it shared the instability of living metabolism and danced always on the same edge of disaster. Unpredictable variations occurred in the matter content of space. The extent, intensity, and configuration of the force fields must be adjusted accordingly — a problem in? million factors which only a computer could solve fast enough. Incoming data and outgoing signals traveled at light speed: finite speed, requiring a whole three and a third seconds to cross a million kilometers. Response could be fatally slow. This danger would increase as Leonora Christine got so close to ultimate velocity that time rates began measurably changing.

Nonetheless, week by week, month by month, she moved on outward.

The multiple cyclings of matter that turned biological wastes back into breathable air, potable water, edible food, usable fiber, went so far as to maintain an equilibrium in the ethyl alcohol aboard. Wine and beer were produced in moderation, mainly for the table. The hard liquor ration was meager. But certain people had included bottles in their personal baggage. Furthermore, they could trade for the share of abstemious friends and save their own issue until it sufficed for a special occasion.

No official rule, but evolving custom, said that drinking outside the cabins took place in the mess. To promote sociability, this room held several small tables rather than a single long one. Hence, between meals, it could double as a club. Some of the men built a bar at one end to dispense ice and mixers. Others made roll-down curtains for the bulkheads, so that the decorous murals could be hidden during boozing hours behind scenes a little more ribald. A taper generally kept background music going, cheerful stuff, anything from sixteenth-century galliards to the latest asteroid ramble received from Earth.

On a particular date at about 2000 hours, the club stood empty. A dance was scheduled in the gym. Most off-duty perso

“Can we not talk business tomorrow, though?” he asked. He was a large, amiable young man, square-featured, his scalp shining pink through close-cropped blond hair.

“I want to discuss this with you at once, while it’s new in my mind,” said Nilsson’s raspy voice, “It came to me in a flash as I was changing clothes.” His appearance bore him out. “Before carrying my thought further, I wish to check the practicality.”

“Jawohl, if you’re supplying the drink and we can keep it short.”

The astronomer found his personal bottle on the shelf, picked up a couple of glasses, and started for a table. “I take water—” Freiwald began. The other man didn’t hear. “That’s Nilsson for you,” Freiwald told the overhead. He tapped a pitcherful and brought it along.

Nilsson sat down, got out a note pad, and started sketching. He was short, fat, grizzled, and ugly. It was known that an intellectually ambitious father, in the ancient university town Uppsala, had forced him to become a prodigy at the expense of everything else. It was surmised that his marriage had been the result of mutual desperation and had turned into a prolonged catastrophe, for despite a child it dissolved the moment he got a chance to go on this ship. Yet when he talked, not about the humanities he failed to understand and hence disdained, but about his own subject … then you forgot his arrogance and flatulence, you remembered his observations which had finally proven the oscillating universe, and you saw him crowned with stars.

“—unparalleled opportunity to get some worthwhile readings. Only think what a baseline we’ll have: ten parsecs! Plus the ability to examine gamma-ray spectra with less uncertainty, high precision, when they’re red-shifted down to less energetic photons. And more and more. Still, I’m not satisfied.

“I don’t believe it’s really necessary for me to peer at an electronic image of the sky — narrow, blurred, and degraded by noise, not to mention the damned optical changes. We should mount mirrors outside the hull. The images they catch could be led along light conductors to eyepieces, photomultipliers, cameras inboard.

“No, don’t say it. I’m well aware that previous attempts to do this failed. One could build a machine to go out through an airlock, shape the plastic backing for such an instrument, and aluminize it. But induction effects of the Bussard fields would promptly make the mirror into something appropriate for a fun house in Grцna Lund. Yes.