Tractor beam

A tractor beam is a device with the ability to attract one object to another from a distance. The concept originates in fiction: the term was coined by E. E. Smith (an update of his earlier "attractor beam") in his novel Spacehounds of IPC (1931). Since the 1990s, technology and research has laboured to make it a reality, and have had some success on a microscopic level. Another method to realize tractor beams is based on the use of biaxial birefringent media. Less commonly, a similar beam that repels is called a pressor beam or repulsor beam. Gravity impulse and gravity propulsion beams are traditionally areas of research from fringe physics that coincide with the concepts of tractor and repulsor beams.

A force field confined to a collimated beam with clean borders is one of the principal characteristics of tractor and repulsor beams. Several theories that have predicted repulsive effects do not fall within the category of tractor and repulsor beams because of the absence of field collimation. For example, Robert L. Forward, Hughes Research Laboratories, Malibu, California, showed that general relativity theory allowed the generation of a very brief impulse of a gravity-like repulsive force along the axis of a helical torus containing accelerated condensed matter. The mainstream scientific community has accepted Forward’s work. A variant of Burkhard Heim’s theory by Walter Dröscher, Institut für Grenzgebiete der Wissenschaft (IGW), Innsbruck, Austria, and Jocham Häuser, University of Applied Sciences and CLE GmbH, Salzgitter, Germany, predicted a repulsive force field of gravitophotons could be produced by a ring rotating above a very strong magnetic field. Heim’s theory, and its variants, have been treated by the mainstream scientific community as fringe physics. But the works by Forward, Dröscher, and Häuser could not be considered as a form of repulsor or tractor beam because the predicted impulses and field effects were not confined to a well defined, collimated region.

The following are a summary of experiments and theories that resemble repulsor and tractor beam concepts:

In July 1960, Missiles and Rockets reported Martin N. Kaplan, Senior Research Engineer, Electronics Division, Ryan Aeronautical Company, San Diego, had conducted experiments that justified planning for a more comprehensive research program. The article indicated such a program, if successful, would yield either “restricted” or “general” results. It described the “restricted” results as an ability to direct an anti-gravitational force towards or away from a second body.

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