In reply to David Roberson's message of Thu, 17 Mar 2016 11:58:43 -0400: Hi, [snip] >Of course the EM drive ship that remains in this extreme case(actually nothing >at all if zero exhaust is present) is at rest which means it has zero kinetic >energy relative to itself. Again, this is not a problem for a normal rocket >that spits out reaction mass. In that case all the missing mass and energy >can be located by analyzing the exhaust stream. This is true regardless of >what reference frame you choose. A normal rocket obeys CoE and CoM whereas >the EM Drive ship does not.
An electric car speeding down the road will also eventually exhaust all it's stored energy, while remaining motionless in it's own rest frame (BTW everything is always motionless in it's own rest frame, that's why it's called "rest"), nevertheless it has considerable kinetic energy relative to the road. I fail to see the difference between this and the EM drive vehicle. Note that the car used it's energy to change the relationship between it's own frame of reference and that of it's surroundings. So did the EM drive vehicle. Kinetic energy always depends on the frame of reference chosen. When either vehicle starts out with a full fuel load, the "correct" frame of reference is the initial frame in which the "fuel tank" was full. If we stick to that frame instead of swapping and changing when we feel like it, then the kinetic energy gained, as the fuel is used, becomes apparent. For the EM drive ship, the "exhaust" is the universe itself. Just think of spacetime as invisible "train tracks", and it all becomes clear. (Made beautifully visible in a Dr. Who episode about the Orient Express. :) ) Acceleration requires force, and all lines of force have two ends. If one end is attached to the EM drive, then the other end must be attached to something. The only thing that would make sense is the fabric of spacetime itself. In short IMO, if it works at all, then this is how it would have to work. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html