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originally posted by: GetHyped
a reply to: BrianFlanders
If you have any better ideas, by all means share them with the academic community.
originally posted by: Aliensun
a reply to: 0bserver1
"Getting us to the Moon in four hours," would be delivering a mush of human remains there. Let's see, there is the acceleration and the deceleration. That would create mush on the rear bulkhead and on the front bulkhead if I'm not mistaken.
originally posted by: Bedlam
I found Annila's explanation to be sort of hard to swallow as well, if it's strictly a photon drive, then you ought to get more thrust by simply removing the cone and turning up the microwaves.
Well, you might need some sort of impedance matching horn. But that's the general idea.
originally posted by: mbkennel
...as it is wildly larger than classical electromagnetic momentum in some experiments.
Light at microwave lengths is the fuel that's being fed into the cavity ... and the EM drive exhausts backwards paired photons," he says. "When two photons travel together, but having opposite phases, then the pair has no net electromagnetic field, and hence it will not reflect back from the metal walls, but goes through.
originally posted by: glend
a reply to: Bedlam
Wouldn't the cone be needed to direct waves that produce the photons backwards else the escape of photons in all directions wouldn't produce any directional thrust.
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.
originally posted by: TheBadCabbie
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.
originally posted by: Bedlam
Except that can't be the explanation.
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)
Thus if the EM wave travelling in a tapered waveguide is bounced between two reflectors, with a large velocity difference at the reflector surfaces, the force difference will give a resultant thrust to the waveguide linking the two reflectors. If the reflectors are separated by a multiple of half the effective wavelength of the EM wave, this thrust will be multiplied by the Q of the resulting resonant cavity, as illustrated in fig 1.