On Nov 3, 2009, at 7:59 PM, Abd ul-Rahman Lomax wrote:
At 07:01 PM 11/3/2009, Horace Heffner wrote:
The model by which the device is said to work looks bogus. I think if
they knew why and how it actually works they could produce a much
better W/a ratio. The device applies force to vacuum elements.
Their theory predicts a change in acceleration with velocity. I think
this is nonsense. Either the device doesn't work at all in space or
its thrust, as perceived by the occupants, does not vary with
velocity.
The only way that the thrust could vary with velocity would be if
it depends on velocity through a material or velocity through a
field of some kind.
I didn't make the claims. See:
http://www.emdrive.com/theorypaper9-4.pdf
for the theory,
http://www.emdrive.com/
for the company.
They show a curve of acceleration vs velocity. It has nothing to do
with anything external. Therefore I think it is bogus. I've done
enough work in this area to believe it is possible to couple to
vacuum inertia though, and that means the possibility of reactionless
EM drives.
A 1 g device should be able to accelerate right on beyond c, and thus
go anywhere in the universe.
The occupants would feel the 1 g
acceleration though, and that is a good thing.
The time to light speed T2 at 1 g is:
T2 = c/g = 3.057x10^7 s = 0.968735 years = about 11 months 20 days
Eh? No, "g" is a measure of acceleration,
Well duh.
but the acceleration produced in a reference frame by a constant
force reduces as the velocity approaches c, while, at the same
time, that acceleration is experienced as the same by the occupants
of the ship, who are now experiencing time dilation and the other
nifty effects of approaching light speed. They never get to light
speed, just closer and closer and closer. The accumulated potential
energy keeps rising.
I'm totally familiar with that pablum. You don't understand. This
is from the reference frame of the ship, which accelerates at a
constant rate g, from the passenger point of view, with no reaction
mass. We have v = a*t, so t = v/a = c/g from their point of view.
I have no idea what this might mean in terms of what would happen if
they should hit some atoms along the way though, as the atom apparent
mass might be infinite. Also, the mass presented to the incoming
atoms would be infinite. A practical case of the irresistible force
and the immovable object paradox?
They would become more and more irresistible, but, unfortunately,
so would anything they hit as their velocity approaches c, and with
time dilation, they will cover a lot of space in cross-section
where there might be something. In any case, the fuel that must be
consumed to continue to accelerate like that .... how big are they,
including fuel?
Read the reference if you have any serious interest. The emdrive.com
page has a branch to a theory page and FAQ I think.
And then how much force is exerted by the drive? The bigger they
are the lower the acceleration for a constant fuel consumption...
Getting significant mass close to c ... forget about it.
Not in the passenger reference frame. They experience constant
acceleration. It is the universe that starts acting weird from their
perspective.
Ah, I wasted a few perfectly good minutes on this.
This is actually a valid line of inquiry. There is a fun book on the
subject, titled "Unconventional Flying Objects, a scientific
analysis", Paul Hill, ISBN 1-57174-027-9. Paul Hill was an ex NASA
Scientist. The book is forwarded by Edgar Mitchell, Apollo 14 Astronaut.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
