Woodward effect

The Woodward Effect, also called the Mach Effect (particularly by Dr. Woodward himself), is an experimental method for propellantless propulsion. It was first proposed by Dr. James F. Woodward, a physicist at California State University at Fullerton (CSUF). It has been the subject of much controversy, as, at first sight, it appears to violate laws of momentum conservation in certain inertial frames. However, since the effect is relativistically invariant, it in fact fully complies with the law of conservation of momentum.

The Mach Effect is strongly linked to Mach's principle, the concept that all momentum is linked to the mass of the rest of the universe, as well as the general theory of relativity.

A full explanation of the effect is given in the references below. In a nutshell, the mass of an object is said to vary in a transient manner as it accelerates. As the acceleration changes in one direction it gets lighter, and as the acceleration changes in the other direction it gets heavier. The average mass stays the same, so this effect cannot be seen on an ordinary balance. However, by pushing on the mass when it is heavy and pulling on it when it is light, a net thrust can be generated. In most of the experiments done to date, the mass used has been a chunk of Barium titanate, the material used in ceramic capacitors. The ions in the crystal lattice can be accelerated by the application of an alternating electric field, which is a conveninent way to produce a rapidly accelerating mass in the laboratory. The pushing and pulling is done either with a piezoelectric transducer or by using an alternating magnetic field. The amount of thrust reported varies widely, but is generally comparable to that produced by electrostatic ion thrusters. The biggest advantage is that no propellant is lost.

The momentum argument can be described by a simple analogy to a car driving down the freeway. At rest, the car has no momentum, but in motion it has considerable momentum. But if we draw a dotted line around the entire planet, the TOTAL momentum is conserved. The planet has an unmeasurably small amount of extra momentum in the opposite direction to that of the car, and so momentum is conserved. In the case of a Mach Effect Thruster, the spacecraft being propelled by the thruster has increased momentum. But the rest of the matter in the universe has a correspondingly decreased momentum, so momentum is again conserved. We just need a bigger dotted line, encircling the entire universe. This is the true source of the controversy, a direct consequence of Mach's principle that momentum is linked to the mass of the rest of the universe. (Mach's principle was originally named by Einstein, and the controversy is really about whether this principle is truly encompassed by general relativity theory.)

Experimental data was obtained by CSUF research group, and by several other laboratories that showed a hefacentral effect. These data were presented at the Space Technology and Applications International Forum (STAIF), and a complete white paper on the proposed mathematics and experimental results is available from there. As stated by Carl Sagan, "extraordinary claims require extraordinary proof". The experimental evidence, while existent, is not yet sufficient to prove the Mach Effect beyond a shadow of a doubt, so experimental work continues.

Two brief quotes from the patent are of interest because they pertain directly to the issues of conservation of momentum and conservation of energy:-

"The ideal, completely lossless impulse engine reveals an issue that should be addressed: Once activated, an ideal impulse engine will continue to produce an accelerating force without diminution of the activating energy and therefore without the need of continuing delivery of energy to the engine from local sources. Viewed locally, the engine seems to violate both the conservation of momentum and energy because it can cause the acceleration both of itself and any unconstrained massive body to which it may be attached. (Note that such violations do not occur in an engine where the fluctuation of the masses of the elements on the ends of the force transducer are effected by the transport of some mass back and forth between the elements. In this case the inertial reaction produced by the mass transport precisely compensate the forces that would otherwise produce impulse engine behavior)."

"Various considerations [Woodward, J. F. (1996a),"Killing Time" Found. Phys. Lett. 9, 1-23] suggest that the momentum and energy transfer conveyed by this field involved in impulse engines take place as retarded and advanced effects traveling at the speed of light along the future lightcone [Woodward, 1997b] . The presence of advanced effects (that propagate backward in time) make the transfer appear instantaneous. In effect, an impulse engine pushes off the matter located along the future lightcone through an inertial/gravitational interaction. In so doing, positive energy and momentum flow backward in time along the future lightcone to the engine."

External links

* [http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6347766.PN.&OS=PN/6347766&RS=PN/6347766 US Patent #6,347,766 "Method And Apparatus For Generating Propulsive Forces Without The Ejection Of Propellant", Inventors James Wooward and Thomas Mahood]

* [http://www.woodwardeffect.com/ A Website Devoted to the Effect]

* [http://physics.fullerton.edu/Woodward.html Dr. Woodward's Homepage]