Reactionless drive

A reactionless drive or inertial propulsion engine (also reactionless thruster, reactionless engine, bootstrap drive, inertia drive, and space drive) is any form of pseudoscientific propulsion not based around expulsion of fuel or reaction mass.

The name comes from Newton's Third Law of Motion, usually expressed as: "For every action, there is an equal and opposite reaction." Such a drive would use a hypothetical form of thrust that does not require any outside force or net momentum exchange to produce linear motion, and therefore necessarily violates the conservation of momentum, a fundamental principle of all current understandings of physics. In addition it can be shown that conservation of energy is violated.

In spite of their physical impossibility, such devices have been often proposed in recent history and are a staple of science fiction.

Physics of reactionless drives

In a sentence: "The underlying problem [with reactionless drives] is that breaking the law of conservation of momentum shatters the entire mathematical framework [of physics]." These devices by their very nature violate the law of conservation of momentum—if a ship with such a drive existed, then any motion of that ship, unaccompanied by the motion of any other material, would cause the center of gravity of the universe to move with it. Furthermore, the total energy of the universe becomes reference frame dependent—energy can only be conserved in the presence of a reactionless drive in (at most) one reference frame, because in all other reference frames the change in kinetic energy of the ship differs from the power expended by the ship. Given that these two laws—the conservation of momentum and the principle of relativity—are so well established (and thoroughly verified) in physics, any ordinary mechanical system purporting to violate the laws is generally dismissed outright.

Swimming in Spacetime

General relativity allows a hypothetical astronaut to "swim" in curved space without using reaction mass, cf. In other words, if spacetime is flat, then an astronaut can change his or her orientation in space through certain body movements (in the same manner as a falling cat can orient itself so that it hits the ground feet-first), but no amount of this sort of exertion will change the position of his center of mass. However, if local spacetime is curved, a similar trick can be used to take advantage of this curvature; mass held in the astronaut's outstretched hands moves in a slightly different path through curved spacetime than mass at the astronaut's feet, and the resulting "force" on the astronaut can change his position. While this concept is allowed by the currently accepted laws of physics, it is not clear how or even if this effect could provide a useful means of accelerating an actual space vehicle.

Types

Oscillation thruster

An oscillation thruster (also known as a stiction drive, internal drive or slip-stick drive) uses the motion of internal masses to create a net thrust. These thrusters include either vibrational or rotating masses, in which one portion of the cyclical motion is high-speed, and the other low-speed, or alternately high and low impulse. The result is that for some of the motion a high force is generated, enough to overcome friction. However on the "return stroke" the force is not high enough, and any motion occurring in the first portion is not reset. In this way the devices "steal" working mass from their supporting surface, a fact that may not be apparent to casual observation.

Basically, an oscillation thruster works just like walking does, one mass is "thrown" backward, "thrusting" the device forward according to conservation of momentum (like a person taking a step forward), then the mass is more slowly brought forward to its initial position (like the person using their step to pull the rest of their body forward). The thruster is allowed to move forward in the first step because the mass is "thrown" back with large enough force to overcome static friction. The "thruster" doesn't move backward in the second step because static friction provides an outside force that overcomes the step (like the ground does when you're walking).

Although there have been many versions proposed, all oscillation thrusters have the following common components:

• Chassis to support a system of masses,
• Conveyor that moves the masses through an asymmetric cycle,
• Power source for the conveyor.

A crucial feature is that these internal masses go through some sort of cyclic motion where the motion in one direction is quicker than in the return direction.

Inventors of oscillation thrusters extrapolate its behavior to mean that it can work in a vacuum in zero gravity.

One of the most famous proposed reactionless drives was the Dean drive. Although Dean himself gave few indications of how his "reactionless drive" was supposed to work, it appears to be an attempt at an oscillation thruster. Other examples of oscillation thrusters are:

• The Thornson Inertial Engine
• Henry Bull’s Impulse Engine of 1935

Quantum Vacuum

Magnetoelectric materials can be electrically polarized by magnetic fields. The quantum vacuum contains randomly fluctuating magnetic fields. A sufficiently small piece of magnetoelectric material can be placed in the quantum vacuum and then rotated 180 degrees. The random magnetic fields can induce a change in electric polarization in the block of material. Somehow this change causes the combined electric and magnetic fields to push the block in one direction while they (the fields themselves, or more technically, the bosons of which these fields are composed) get pushed in the other direction. The trick doesn't work if the magnetoelectric block is too large but curiously it should work if there's a grid of millions of tiny blocks working together. This mechanism was first suggested in December 2009 and apparently has not yet been tested. The author of the original paper suggested that the mechanism could be used would be powerful enough to reorient satellites if a material with a magnetoelectric constant ten times higher than the strongest such materials known today could be found.

Gyroscopic Inertial Thrusters

While the general consensus in dogmatic science insists that inertial propulsion is "impossible" one adherant to the concept (David E. Cowlishaw) operated an open internet forum on the subject from 1996 through 2003, and reported numerous proofs of physical testing, and gathered reports from over 20 others also claiming successful physical experiments in the field.

His GIT (Gyroscopic Inertial Thruster) concept reportedly broke the supposed barrier between angular and linear accelerations and momentum, by utilizing a motion profile that operated on the frame with both (angular and linear accelerations).

A variable angular velocity eccentric mass (speeding up and slowing down an off-center mass cyclically in a frame), produces BOTH angular accelerations on the frame (angular oscillation or the "twist"), AND linear oscillations on the frame (movement toward and away from a rest position in space, or the"hula").

Working models reportedly function by introducing a third motion actor to the well tested and represented variable velocity motion profile.

By introducing inverse in angular direction, but equal in torque force spin changes in the eccentric, a means to "rectify" angular accelerations to produce linear spacial displacement was achieved.

By introducing orbital spin enabled eccentric mass accelerations, that produce a torque or twisting force on the frame in angular opposition to the angular portion of the variable velocity eccentric mass accelerations, linear displacement in space was achieved by "force rectifying" the angular "twist" accelerations.

This in effect transfers negatively acting forces on the frame from the linear position changes produced by the eccentric's POINT MASS effects on the frame, into and out of "another dimension" for the negatively acting portion of the cycle.

That extra dimension is the spin axis of the eccentric orbital, storing reverse momentum from the point mass' motion on the negative side of the cycle, and releasing that stored momentum toward the forward directed portion of the cycle.

An easily grasped example is the variable velocity eccentric "dumb hammer" slinger on train tracks. This is a working example of the centrifugal thrust concept that actually works, and has been used repeatedly throughout history, often as a deceptive experimental "proof" (until you lift it off the tracks).

The deceleration toward the rear of the cart is accomplished by generating a torque or twisting force on the earth, rather than by pushing the cart backwards to slow the hammer down. On the opposite side of the cycle, speeding the hammer back up, again it does so by generating a torque through the wheels and rails, rather than pushing linearly backwards on the cart. The "imaginary" centrifugal force then pulls the cart forward.

The GIT style machines simply replace the torque exchanges with the earth, with a footloose, onboard equivalent set of torque forces, generated by the opposing torques of a spin acceleration enabled eccentric mass. This is linear spacial displacement using an orbital "angular mass" spin torque force to rectify the "point mass" tangential torque accelerations to produce a linear thrust.

The inventor is no longer publishing his advancements in this field, and his website is no longer active, however the published works are available on a European archive site: http://archive.go-here.nl/open.org/davidc/update34.htm

David E. Cowlishaw is active again, and publishing his work on facebook. A photo journal is being compiled on this web address on facebook: http://www.facebook.com/album.php?aid=30492&id=100001651110627&l=e0295f2c09

Electromagnetic tethers

At first glance, a device called the electrodynamic tether might appear to constitute a reactionless drive because it does not expel reaction mass. But it is still not reactionless, as electromagnetic fields can carry energy and momentum.

The fundamental scientific problem is one of momentum transfer. If there is no momentum transfer, the postulated device is classified as a "reactionless" drive and labelled a fraud. If there is a mechanism for momentum transfer, then the device is classed as a reaction drive and is therefore by definition not a "reactionless" drive. Tethers do have a mechanism for momentum transfer and although they do not expel reaction mass like a rocket, they transfer momentum and hence cannot be a true reactionless drive.

See also

• Perpetual motion
• Abraham-Minkowski controversy
• Stochastic electrodynamics, for related speculations in theoretical physics
• EmDrive, which consists of a resonant cavity flooded with microwave radiation
• Woodward effect a hypothesised mechanism for reactionless drives (that is not generally accepted)
• Inertialess drive
• Spindizzy, an example in science fiction
• Bernard Haisch
• Harold Puthoff

External links

• "Breakthroughs" commonly submitted to NASA - Explains Oscillation thrusters, Gyroscopic Antigravity, and Electrostatic Antigravity.
• Reactionless Propulsion (Not) at MathPages