EmDrive - Cheap Spaceflight and Hovercars

This could rewrite the physics books if true.. but I still have some doubts. Though the inventor seems to be getting plenty of grants and interest from government agencies.

www.emdrive.com...

And from here..

www.eureka.findlay.co.uk...

A reactionless force motor, designed for space use, has the potential to drive objects on until they reach speeds close to that of light. Upon first inspection it looks as if it cannot possibly work, however one of the UK's leading engineers has developed a prototype which has been endorsed by academics and government alike.....

.......the Emdrive is a resonating bottle full of microwaves. Because microwaves are a low frequency form of light, their behaviour is governed by Einstein's Theory of Special Relativity. And while microwaves and other forms of electromagnetic radiation may be thought of as very fast moving particles, they also have to be thought of as waves. At the same time that the constituent particles are moving at light speed, or their phase velocity, energy is transferred by the wave aspect travelling at group velocity. Group velocity is the result of waves of different wavelengths interacting with each other. According to Einstein, the phase velocity of electromagnetic waves is the speed of light in the appropriate medium whatever happens and in whatever moving frame of reference the observer happens to be; group velocity, however, varies. Group velocity can be any speed from stationary to light speed (with a few physicists suggesting the additional possibility of faster than light). This varies the level of momentum imparted when striking an impenetrable barrier, and thus the force exerted on it. Hence, it is possible to have a bottle full of electromagnetic waves exerting more force on one end than the other, whereas this is not possible for anything else that an engineer would normally be expected to encounter.

Ummm... ok~ I got the part where it says it uses microwaves... but ummm...in simple English~ How does it work? don't have time to visit the links atm, as I'm just heading out the door now to go home.. Hopefully will have some time tonight to take a peek

Otherwise... interesting

The physics of this is actually sound, though only if you are a subscriber of the standard model.

What is happening is there is pressure differential between the way particles captured within a confinement act versus the wave function that is propagated outwards beyond a barrier of some kind. The resulting pressure differential creates a forwards thrust.

Although this level of thrust would be on par with ion thrusters...

Like the ion thrusters the EM thrusters relies on a tiny constant force of acceleration. Over time the force will add to the velocity of the object and theoretically it could reach a % of light speed.

Though to say that it would be a significant % of light speed is a little misleading.

It would take such a vast length of time to build up speed, we would all be dead and our sun would have gone super nova before this engine had a chance to build enough speed to be anywhere near even 20% light speed.

And the chances are that even before then it would have met it's doom by coliding with some object as this tech goes in only one direction....

Here is an image of the prototype.

Anyway... if you want to read up more on this you can go here..

A Theory of Microwave Propulsion for Spacecraft

Principle of Operation

At first sight the idea of propulsion without propellant seems impossible. However the technology is firmly anchored in the basic laws of physics and following an extensive review process, no transgressions of these laws have been identified.

The principle of operation is based on the well-known phenomenon of radiation pressure. This relies on Newton’s Second Law where force is defined as the rate of change of momentum. Thus an electromagnetic (EM) wave, travelling at the speed of light has a certain momentum which it will transfer to a reflector, resulting in a tiny force.

If the same EM wave is travelling at a fraction of the speed of light, the rate of change of momentum, and hence force, is reduced by that fraction. The propagation velocity of an EM wave, and the resulting force it exerts, can be varied depending on the geometry of a waveguide within which it travels. This was demonstrated by work carried out in the 1950’s. (CULLEN, A.L. ‘Absolute Power Measurements at Microwave Frequencies’ IEE Proceedings Vol 99 Part 1V 1952 P.100)

Hope that helps,

All the best,

NeoN HaZe.

[edit on 23-4-2007 by Neon Haze]

Well .. here we are in 2015 - Almost exactly 8 years later and NASA has confirmed that this could work ..

S&F

a reply to: Neon Haze

I'm glad you qualified the standard model bit. I am not so much a fan - I think the universe is much simpler at the core - have you seen this model? You need to watch a few lectures without emotion to get on his train - he disses a few rather notable people along the way, but to a large degree justifiably.
I would love his take on this subject.

originally posted by: x08
Ummm... ok~ I got the part where it says it uses microwaves... but ummm...in simple English~ How does it work? don't have time to visit the links atm, as I'm just heading out the door now to go home.. Hopefully will have some time tonight to take a peek

Otherwise... interesting

Dr White has a working theory but really right now it's just a theory. it predicted results and experimental data supported that theory though that is not enough to say the theory is true. right now Dr White and Mr Paul and the rest of his team are appalled at the sensationalized nature of articles on thier work.

they are working on improving the signal to noise ratio of thier experiments to beat down the theories of spurious signals to more completely rule out objections to thier research. thier immediate goal is to get a reliable thrust of 100 micronewtons necessary to send it to Glen Research Center for replication due to the sensitivity limits of Glenn's torsion balance. They are also working towards a replication of the superconducting version of the EM drive which will approach or surpass 1 newton.

thats about 9/10s of a pound of thrust. thats a long ways off from the thrust needed to lift something off the surface of the earth but even micronewtons is enough to reasonably power in space applications.