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.