Robin's example of the electric car is different than the EM drive since it
allows the evaluation of the conservation of momentum. The road increases
its momentum in the opposite direction the car does. In the EM case there
is no apparent conservation of momentum--at least I do not know how to
calculate it. Does the entire space time existence change its momentum?
Maybe Robin could identify how momentum is conserved in the EM drive.
Bob Cook
-----Original Message-----
From: mix...@bigpond.com
Sent: Thursday, March 17, 2016 1:26 PM
To: vortex-l@eskimo.com
Subject: Re: EXTERNAL: Re: [Vo]:Re: EM Drive(s)
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
