autumn colors, but where the little village of Rutter's Fort stood on that other line of probability, the white towers of an apartment-city rose—the living quarters of the plant personnel.
The rocket that was to take him to headquarters was being hoisted with a crane and lowered into the firing-stand, and he walked briskly toward it, his rifle and musette slung. A boyish-looking pilot was on the platform, opening the door of the rocket; he stood aside for Verkan Vall to enter, then followed and closed it, dogging it shut while his passenger stowed his bag and rifle and strapped himself into a seat.
"Dhergabar Commercial Terminal, sir?" the pilot asked, taking the adjoining seat at the controls.
"Paratime Police Field, back of the Paratime Administration Building."
"Right, sir. Twenty seconds to blast, when you're ready."
"Ready now." Verkan Vall relaxed, counting seconds subconsciously.
The rocket trembled, and Verkan Vall felt himself being pushed gently back against the upholstery. The seats, and the pilot's instrument panel in front of them, swung on gimbals, and the finger of the indicator swept slowly over a ninety-degree arc as the rocket rose and leveled. By then, the high cirrus clouds Verkan Vall had watched from the field were far below; they were well into the stratosphere.
There would be nothing to do, now, for the three hours in which the rocket sped northward across the pole and southward to Dhergabar; the navigation was entirely in the electronic hands of the robot controls. Verkan Vall got out his pipe and lit it; the pilot lit a cigarette.
"That's an odd pipe, sir," the pilot said. "Out-time item?"
"Yes, Fourth Probability Level; typical of the whole paratime belt I was working in." Verkan Vall handed it over for inspection. "The bowl's natural brier-root; the stem's a sort of plastic made from the sap of certain tropical trees. The little white dot is the maker's trademark; it's made of elephant tusk."
"Sounds pretty crude to me, sir." The pilot handed it back. "Nice workmanship, though. Looks like good machine production."
"Yes. The sector I was on is really quite advanced, for an electro-chemical civilization. That weapon I brought back with me—that solid-missile projector—is typical of most Fourth Level culture. Moving parts machined to the closest tolerances, and interchangeable with similar parts of all similar weapons. The missile is a small bolt of cupro-alloy coated lead, propelled by expanding gases from the ignition of some nitro-cellulose compound. Most of their scientific advance occurred within the past century, and most of that in the past forty years. Of course, the life-expectancy on that level is only about seventy years."
"Humph! I'm seventy-eight, last birthday," the boyish-looking pilot snorted. "Their medical science must be mostly witchcraft!"
"Until quite recently, it was," Verkan Vall agreed. "Same story there as in everything else—rapid advancement in the past few decades, after thousands of years of cultural inertia."
"You know, sir, I don't really understand this paratime stuff," the pilot confessed. "I know that all time is totally present, and that every moment has its own past-future line of event-sequence, and that all events in space-time occur according to maximum probability, but I just don't get this alternate probability stuff, at all. If something exists, it's because it's the maximum-probability effect of prior causes; why does anything else exist on any other time-line?"
Verkan Vall blew smoke at the air-renovator. A lecture on paratime theory would nicely fill in the three-hour interval until the landing at Dhergabar. At least, this kid was asking intelligent questions.
"Well, you know the principal of time-passage, I suppose?" he began.
"Yes, of course; Rhogom's Doctrine. The basis of most of our psychical science. We exist perpetually at all moments within our life-span; our extraphysical ego component passes from the ego existing at one moment to the ego existing at the next. During unconsciousness, the EPC is 'time-free'; it may detach, and connect at some other moment, with the ego existing at that time-point. That's how we precog. We take an autohypno and recover memories brought back from the future moment and buried in the subconscious mind."
"That's right," Verkan Vall told him. "And even without the autohypno, a lot of precognitive matter leaks out of the subconscious and into the conscious mind, usually in distorted forms, or else inspires 'instinctive' acts, the motivation for which is not brought to the level of consciousness. For instance, suppose, you're walking along North Promenade, in Dhergabar, and you come to the Martian Palace Café, and you go in for a drink, and meet some girl, and strike up an acquaintance with her. This chance acquaintance develops into a love affair, and a year later, out of jealousy, she rays you half a dozen times with a needler."
"Just about that happened to a friend of mine, not long ago," the pilot said. "Go on, sir."
"Well, in the microsecond or so before you die—or afterward, for that matter, because we know that the extraphysical component survives physical destruction—your EPC slips back a couple of years, and re-connects at some point pastward of your first meeting with this girl, and carries with it memories of everything up to the moment of detachment, all of which are indelibly recorded in your subconscious mind. So, when you re-experience the event of standing outside the Martian Palace with a thirst, you go on to the Starway, or Nhergal's, or some other bar. In both cases, on both time-lines, you follow the line of maximum probability; in the second case, your subconscious future memories are an added causal factor."
"And when I back-slip, after I've been needled, I generate a new time-line? Is that it?"
Verkan Vall made a small sound of impatience. "No such thing!" he exclaimed. "It's semantically inadmissible to talk about the total presence of time with one breath and about generating new time-lines with the next. All time-lines are totally present, in perpetual co-existence. The theory is that the EPC passes from one moment, on one time-line, to the next moment on the next line, so that the true passage of the EPC from moment to moment is a two-dimensional diagonal. So, in the case we're using, the event of your going into the Martian Palace exists on one time-line, and the event of your passing along to the Starway exists on another, but both are events in real existence.
"Now, what we do, in paratime transposition, is to build up a hypertemporal field to include the time-line we want to reach, and then shift over to it. Same point in the plenum; same point in primary time—plus primary time elapsed during mechanical and electronic lag in the relays—but a different line of secondary time."
"Then why don't we have past-future time travel on our own time-line?" the pilot wanted to know.
That was a question every paratimer has to answer, every time he talks paratime to the laity. Verkan Vall had been expecting it; he answered patiently.
"The Ghaldron-Hesthor field-generator is like every other mechanism; it can operate only in the area of primary time in which it exists. It can transpose to any other time-line, and carry with it anything inside its field, but it can't go outside its own temporal area of existence, any more than a bullet from that rifle can hit the target a week before it's fired," Verkan Vall pointed out. "Anything inside the field is supposed to be unaffected by anything outside. Supposed to be is the way to put it; it doesn't always work. Once in a while, something pretty nasty gets picked up in transit." He thought, briefly, of the man in the black tunic. "That's why we have armed guards at terminals."
"Suppose you pick up a blast from a nucleonic bomb," the pilot asked, "or something red-hot, or radioactive?"
"We have a monument, at Paratime Police Headquarters, in Dhergabar, bearing the names of our own personnel who didn't make it back. It's a large monument; over the past ten thousand years, it's been inscribed with quite a few names."
"You can have it; I'll stick to rockets!" the pilot replied. "Tell me another thing, though: What's all this about levels, and sectors, and belts? What's the difference?"
"Purely arbitrary terms. There are five main probability levels, derived from the five possible outcomes of the attempt to colonize this planet, seventy-five thousand years ago. We're