In Dune the popular method of traversing through another dimension (or something like that) is used yet again. Not anybody can travel at lightspeed, however. They have to pay high prices to an organization called the Spacing Guild (no -- not the kids who are spacing out in study hall, a different kind of Spacing Guild). This organization is made up of what is probably a new branch of humankind (see extraterrestrials in Dune) that has mutated from excessive use of the drug commonly called melange, a product of the sandworms on the planet Dune.

Since machines that seem remotely intelligent to anyone have been destroyed and banned from future use by the Bulterian jihad, Guild Navigators must resort to using melange. When taken in great quantities, this drug gives the user limited prescience (the ability to see the future, think of it this way: pre = before, science = knowledge). This allows the Guild Navigators to maneuver through this "other dimension" (for lack of a better name) without hitting anything that is "reflected" into the "other dimension".

Remember kids: don't do drugs! You'll turn into a fish-like Guild Navigator with no ships to navigate! (OK, not really, but you get the point).