Forgive the slight shift of topic, gang, but I have an "in story" techno-babble (or would that be a spice-babble?) question.
Like several of us in this discussion, I read the novels before seeing the Lynch adaptation. Actually, I felt motivated to read the original novel when I learned the film project was finally underway. (There were several false starts including one that would have involved H.R. Giger providing the major designs...and we did get a few paintings from that failed attempt.) I was 21 or 22 at that time. I can't remember whether I read the next two in the series before or after I saw the movie. Hey, I'm 50 now and I've always been a tad absent minded, anyway. I'll be lucky to remember my own name by the time I hit 60.
Sorry, going on a tangent within my own post. Back to the point.
David Lynch gives viewers the impression that melange gave the Guild Nagivators the literal ability to "fold space" (as the phrase goes). In effect, they are biological "jump drives" or "warp engines". And it's the melange discovered on Arrakis that gave them this ability. Well, that's the impression he gave me.
But I inferred a very different concept from the books. The Spice doesn't give the Navigators the ability to teleport themselves and a portion of their surroundings (namely, the Guild highliners and their contents). Rather, it just gives them the ability to far enough into the near future to know where they need to be. They relay this information to "armies" of Second and First Stage Navigators who interpret this information into mathmatical formula, numbers that allow them to manually "tune" hardware akin to particle colliders. When finally activated, these colliders or engines creates a space-time distortion that teleports the highliner from star system A to star system B in the wink of an eye. Before the Butleran Jihad, the "tuning" (read: programming) of the engines was done by computers. Afterwards, when computers were outlawed, huge numbers of humans "hopped up" on Spice solved the equations and adjusted settings upon "dumb" hardware. When fully "tuned", somebody would "throw the switch" and the ferry would vanish from orbit around Corrino (or wherever) and reappear high over Arrakis.
But some with whom I've communicated feel the Navigators invoked the granddaddy of mentally assisted teleportations. If so, how did they do it before Arrakis was discovered and the infamous Spice?