Because the Dune series is set on multiple planets, the problem of space travel arises.  How can all these species interact with one another on a regular basis when their planets are light years apart?  This problem is solved quite succinctly in Dune through the folding of space. 

In Heretics of Dune, the fifth book in Frank Herbert’s series, more ships from a greater array of planets have access to folding space travel.  In Herbert’s fantasy, this means greater competition for available resources, which were previously isolated due to space travel time constraints. 

Also, spying becomes a much more viable pastime, as separate colonies can now go in person to see new developments on distant planets, and return home to relay this reconnaissance efficiently. 

Much of the method behind folding space is not written about explicitly in the Dune series, but its basic concept is clear: space can be “folded” in order to create a “wormhole” that transports a ship from one distant point in space to the next, within a fraction of the time. 

Surely this is an impossible feat in present day science…