Historical research guide · 0716 · 2015
Theory of a Mach Effect Thruster I
Heidi Fearn · Adam Zachar · Keith Wanser · James Woodward
In one minute
A Mach effect thruster is a stack of ceramic capacitor discs driven hard at its mechanical resonance which, its builders report, pushes without throwing anything overboard. Heidi Fearn and her colleagues at Cal State Fullerton — with James Woodward, whose idea it is — set out both halves of the case. The hardware: lead-zirconium-titanate discs bolted to a brass reaction mass, run at 39.3 kilohertz and 234 volts on a torsion balance that resolves a tenth of a micro-newton, giving a clear two-micro-newton thrust that reverses when the device is turned round in its cage. The theory: Mach’s principle, that a body’s inertia is its gravitational interaction with all the rest of the mass-energy in the universe. Accelerate a body whose internal energy is changing and its mass fluctuates; push while it is heavy, pull while it is light, and the result is steady thrust with no propellant. They derive Woodward’s mass-fluctuation formula twice — once from linearised Einstein gravity, once from the fully Machian Hoyle-Narlikar theory.
Connection
Chapter 3 says inertia is a field effect rather than a property matter simply has, and this is what that claim looks like when someone builds it into a bench instrument: if the vacuum and the distant mass of the universe set a body’s inertia, then a body whose energy content is changing has an inertia you can modulate. Chapter 8 cares about the consequence — thrust with no reaction mass — and about the number, which is micro-newtons on a balance that resolves a tenth of one.
From the source
The Mach effect thruster is a propellantless space drive that uses Mach’s principle to produce thrust in an accelerating material undergoing mass-energy fluctuations. The operating idea is to push on the object while it is more massive and pull back while it is less massive, which produces a steady linear acceleration detectable in the laboratory. The devices run on 100 to 200 watts of electrical power and produce thrusts of a few micro-newtons.Abstract; Sect. 1, Introduction
The device is a stack of lead zirconium titanate dielectric discs acting as capacitors, bolted to a reaction mass inside a Faraday cage on a torsion balance capable of measuring forces of 0.1 micro-newtons. Driven at its 39.3 kHz resonance with 234 volts, drawing about 270 watts, it produced a clear thrust of approximately 2 micro-newtons during the 14-second pulse of a 32-second run. Simply charging and discharging a capacitor produces no Mach effect: the capacitor must also be undergoing bulk accelerations of the kind produced by electrostriction.Sect. 2, The MET Experiment; Figs. 1 and 3
Two obvious artefacts are excluded by construction. Thermal expansion cannot produce the thrust because six stainless steel bolts hold the stack under compression and the aluminium and brass expand faster than the PZT, so the crystal stack is compressed rather than pushed. Dean drive vibration cannot produce it either, because such a signal would not reverse when the device is rotated 180 degrees in its cage — and the reported thrust is the difference between forward and reversed runs, which cancels every non-reversing signal.Sect. 2, paragraph following Fig. 4
Woodward’s mass fluctuation formula follows from linearised general relativity. Writing Einstein’s field equations in the weak-field Maxwell-like form using Forward’s correspondences, taking the time component, and then using the momentum form of the geodesic equation — which, unlike the coordinate geodesic, does not cancel the mass and so permits a time-varying mass — yields a Poisson equation for the potential carrying two extra terms: the second time derivative of the mass over the mass, and the square of the first time derivative over the mass squared.Sects. 3.1 and 3.2, Eqs. (1) to (21)
The same mass-fluctuation terms come out of the Hoyle-Narlikar theory of gravitation from first principles. That theory replaces every mass term with a direct particle interaction, so the mass of a particle arises solely from its interaction with the rest of the universe; its Lagrangian is symmetric and can be written in half-retarded and half-advanced mass waves; and it reduces to Einstein’s field equations in the limit of a smooth fluid distribution of matter plus a conformal transformation. Taking the extra terms alone reproduces Woodward’s formula apart from a numerical factor of four thirds.Sects. 3.6 and 3.7, Eqs. (26) to (44)
The standing objection to Hoyle-Narlikar theory, raised by Hawking in 1965, was that the advanced field would carry infinite energy in an expanding universe, because retarded waves are red-shifted and advanced waves blue-shifted. The authors report this resolved by the accelerating expansion, which creates a Rindler horizon that acts as a cutoff for the advanced wave integral, removing the divergence.Sect. 3.7, final paragraph
The way in
https://doi.org/10.4236/jmp.2015.611155How to cite it
Heidi Fearn, Adam Zachar, Keith Wanser, James Woodward (2015) Theory of a Mach Effect Thruster I doi:10.4236/jmp.2015.611155