Hendrik Casimir was a Dutch physicist. His 1948 experiment proved that when two uncharged plates are placed very close to one another, there is an attractive force between them where there should be none. Casimir theorized that neutral space, with zero energy, has quantum fluctuations which spontaneously split into regions of positive and negative energy then recombine going back to a zero energy state. The experiment has been replicated several times. When the distance between the plates is very small (sub-micron), the force is very strong.
Nobody knows what would happen if you could actually collect negative energy. The FTL drive postulated in the book assumes that you can collect enough negative energy to "punch through" the fabric of space. Since there is no space where there is no energy, it takes zero time to go from point A to point C thus allowing you to go (mathematically) faster than the speed of light without violating relativity.
The Casimir Effect and the production of negative energy has been proposed as the basis of:
PPT Throwers (very powerful cutting devices)
PPT Tunnels (a way of traveling faster than light)
PPT Transceivers (how the Vuduri connect mind-to-mind: giving rise to the Overmind)
MINIMCOM later developed several variations on using PPTs. He developed "roadgrader" fans for leveling large swatches of land. He also developed the ability to force project a continuous set of PPT tunnels allowing him to travel at nearly 1000 times the speed of light. He also developed a moving ring of PPT tunnels which allowed him to transport objects from one place to another instantaneously, similar to the transporter made famous in Star Trek. However, he got rather indignant when his method was compared to a transporter created in science fiction.
To read about this on Wikipedia, click here.