The Brian Herbert/Kevin J. Anderson Legends of Dune prequel trilogy (2002–2004) establishes that the Holtzman effect is discovered by — and named after — scientist and inventor Tio Holtzman immediately prior to the Butlerian Jihad, some 10,000 years before the events of Dune. The technology is employed for defensive force fields capable of scrambling the gel-circuitry of thinking machines, the force of sentient computers and robots who seek to enslave and exterminate mankind. Networks of towers generating the field from the surface protect entire planets from machine attacks.
Residing on the planet Poritrin, Holtzman's career is on the wane, as he has not invented anything significant in several years. He comes across the work of Norma Cenva, a woman from Rossak; realizing her genius, he invites her to come work with him on Poritrin. The machines soon realize that their cymeks (human-machine hybrids) can slip though the planetary force fields to destroy the transmitters because they possess human brains, which are unaffected by the scrambler fields. Cenva has the idea to use the field as an offensive weapon, projecting it with portable transmitters to knock out machines and their installations. Holtzman later calculates that the field can be modified to prevent penetration from physical projectiles; Cenva agrees, correcting the flaws in his concept but noting that objects can still pass through the shield at a slow enough speed. The human forces start installing these new shields on their battleships and most ground forces. However, as it is still a new technology at the time, the shields tend to overheat with too much use and deactivate. As time passes, Holtzman discovers that the young dwarfish woman is much more creative than he, and after being upstaged by her twice, begins to dislike her. Eventually he takes credit for Cenva's mathematical theories, which lead to many practical uses for Holtzman's original discovery, including the Holtzman Drive, Holtzman Shields, suspensors and glowglobes. Cenva is also credited with the realization that hitting a Holtzman field with a lasgun beam results in a large and unpredictable explosion. Her theory is proven in the 2003 novel Dune: The Machine Crusade, when Holtzman himself is killed by the explosion from such an interaction during a slave uprising on Poritrin.
The Legends of Dune series also establishes that Cenva invents the theory of space folding in 177 B.G. during the Butlerian Jihad after years of working on Holtzman's original field equations. By 174 B.G. she had built a prototype space-folding ship, and soon she and industrialist Aurelius Venport establish a shipyard on the planet Kolhar to produce what would eventually be called heighliners. Within a decade, Venport puts the space-folding technology and shipyards at the disposal of the Jihad forces. Initially, foldspace travel is not completely accurate or safe; only about nine out of every ten heighliners make it to their final destination. Realizing that the spice melange amplifies her psychic and calculative abilities, Norma pioneers the use of massive concentrated doses to presciently perceive space/time. In 88 B.G. she discovers that this is the way to safely navigate foldspace, and essentially becomes the first Navigator. That same year, Norma's son Adrien Venport founds the Foldspace Shipping Company, which later becomes the Spacing Guild and eventually monopolizes space commerce, transport and interplanetary banking. Cenva's name is eventually forgotten by history, but she is more interested in improving defensive shields and developing foldspace travel to make it safer and more efficient. Her efforts help humanity defeat the thinking machines.
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