the interplanetary runs. They take the dull interstellar watches as a matter of duty, by turns.”
Here and there the tunnel branched off, signs indicating the way to Alpha Centauri Jump, Tau Ceti Jump, Epsilon Eridani Jump, all the long-colonized systems. Those were for passengers; freight went by other beams. There was no great bustle along any of the tubes. Comparatively few Earthlings had occasion to visit outsystem on business; still fewer could afford it for pleasure, and of course no colonial came here without a grudging O.K. The Protector had trouble enough; he was not going to expose the mother planet and its restless billions to new ideas born under new skies, nor let any more colonials than he could help see first-hand what an inferior position they held. That was the real reason for the ban, every educated Terrestrial knew as much. The masses, being illiterate, swallowed a vague official excuse about trade policy.
The branches leading to Sirius Jump, Procyon Jump, and the other attained but uncolonizable systems, were almost deserted. Little came from such places—perhaps an occasional gem or exotic chemical. But relay stations had been established there, for ‘casting to more useful planets.
Ryerson’s heart leaped when he passed a newly activated sign: an arrow and WASHINGTON 5584 JUMP burning above. That tunnel would be filled, come next week!
He should have been in the line. And Tamara. Well, there would be later waves. His passage was already paid for, he had had no difficulty about transferring to another section.
To make conversation, he said through a tightness: “Where are the bulkheads?”
“Which ones?” asked Maclaren absently.
“Safety bulkheads. A receiver does fail once in a great while, you know. That’s why the installations here are spread out so much, why every star has a separate ‘caster. There’s a vast amount of energy involved in each transmission—one reason why a ‘casting is more expensive than transportation by spaceship. Even a small increment, undissipated, can melt a whole chamber.”
“Oh, yes. That.” Maclaren had let Ryerson get pompous about the obvious because it was plain he needed something to bolster himself. What itched the kid, anyhow? One should
think that when the Authority offered a fledgling a post on an expedition as fundamental as this—Of course, it had upset Ryerson’s plans of emigration. Rut not importantly. There was no danger he would find all the choice sites on Rama occupied if he came several weeks late: too few people had the fare as it was.
Maclaren said, “I see what you mean. Yes, the bulkheads are there, but recessed into the walls and camouflaged. You don’t want to emphasize possible danger to the cash customers, eh? Some technic might get annoyed and make trouble.”
“Some day,” said Ryerson, “they’ll reduce the energy margin needed; and they’ll figure how to reproduce a Frank tube, rather than manufacture it. Record the pattern and recreate from a matter bank. Then anyone can afford to ride the beams. Interplanetary ships, even air and surface craft, will become obsolete.”
Maclaren made no answer. He had sometimes thought, more or less idly, about the unrealized potentialities of matter-casting. Hard to say whether personal immortality would be a good thing or not. Not for the masses, surely! Too many of them as it was. But a select few, like Terangi Maclaren—or was it worth the trouble? Even given boats, chess, music, the No Drama, beautiful women and beautiful spectroscopes, life could get heavy.
As for matter transmission, the difficulty and hence the expense lay in the complexity of the signal. Consider an adult human. There are some 1014 cells in him, each an elaborate structure involving many proteins with molecular weights in the millions. You had to scan every one of those molecules— identify it structurally, ticket its momentary energy levels, and place it in proper spatio-temporal relationship to every other molecule—as nearly simultaneously as the laws of physics permitted. You couldn’t take a man apart, or reassemble him, in more than a few microseconds; he wouldn’t survive it. You couldn’t even transmit a recognizable beefsteak in much less of a hurry.
So the scanning beam went through and through, like a blade of energy. It touched every atom in its path, was modified thereby, and flashed that modification onto the transmitter matrix. But such fury destroyed. The scanned object was