At 06:35 PM 11/7/2009, [email protected] wrote:
First, let me state for the record that I have serious doubts that this device
works, however I'm trying to keep an open mind, and envisage a way in which it
*might* work. The reason for this is their claim to have measured 16
mN of force
and calculated 16.6 mN. That's awfully close for pure coincidence.
Indeed. I don't think it's a coincidence. It's a scam. Seriously.
Sure there could be a way that it might work. But, remember, there is
general agreement here that his theory is bogus. And if his theory is
bogus, what then is the meaning of the coincidence between theory and
result? How many runs did he do? What was the variation?
Look, this is so full of holes it's amazing you can even see the site
and the documents, i.e., that there is anything left. It's not
marginal. It's not "unknown mechanism," remember, he is claiming that
ordinary physical theory applies to this. Why would he do that?
Because if he claims unknown physics, he will not be able to snow
possible funding sources, they will be more wary.
>>I think the original author's intent was this (though I didn't study
>>it properly
>>and may have completely misunderstood):-
>>
>>The drive consumes energy at a constant rate, because we supply energy at a
>>constant rate.
>
>Who (and where) is "we"? I hate to be a stickler, but it's important
>here to become very precise. Where is the energy coming from? It
>makes a difference. It looks to me like the emdrive trick is a result
>of mixing frames of reference.
I assumed that the energy would eventually be carried on board, but that
obviously wasn't the case during their experiments.
So, energy is being supplied to the device. How? If energy is
supplied, this will create forces. Think about it. If the energy
comes from a source that is stored on board ... and it could be, this
thing for the tests only has to run for a short time, there could be
batteries that could handle it (but I see cables).
The descriptions of the demonstrations are extremely sketchy. The
force apparently causes the device to rotate on a low-friction
bearing (air bearing?). But when the device is turned off, there is
first acceleration for a time, then a fairly sharp downturn, itself
mysterious, and then rapid decline of speed, as if it were being
braked. Not what we would see from a very low friction. He presents
the data as if this were linear acceleration, it wasn't. It was
rotation, so the "distance travelled" was ... zero. There is at least
one electric motor on board, to pump the cooling water through that
big radiator. Turn that motor on, torgue is generated in the shaft to
the impeller, and the motor, if free to rotate, will spin in the
opposite direction. When did the pump turn on? If it turned on by
thermostatic control, that would explain why there was no
acceleration at first. The time of the start of acceleration, though,
was *before* the cavity reached frequency lock.
Suppose the spinning of the assembly was caused by the
counter-rotation of the motor shaft and what is attached to it. What
would happen when the pump was turned off? The rotation would stop as
the pump rotor slowed down and stopped. Conservation of angular
momentum. If part of you spins one way, suspended in space you are,
then part of you must spin the other way, so that the sum of angular
momenta remains constant.
How much force is generated by a motor? I'm going to guess that it
could be a lot more than 16 mN! Hold decent sized motor in your hands
and turn it on, good chance it twists itself out of your hands! Feel
an electric drill when you spin it up. You can feel the force.
>Heat is the kinetic energy of individual particles or photons.
>Kinetic energy requires a frame of reference. What's the frame? If it
>is the "craft," which is where the energy conversion is taking place,
>and there is no interaction ("reactionless") or emission of energy
>(the same)
> then there is no kinetic energy at all, unless it is
>entirely internal, i.e., heat or rotary inertia or oscillatory
>inertia, or other contained forms of kinetic energy. Inside the "black box."
Heat is obviously internal, however that's only the waste, not the main
component. If this thing works at all, then I see it working as follows:
"Waste" is a bit confusing. It's chaotic motion, but it's still
kinetic energy. From the stationary frame, the sum of the kinetic
energy of all the particles is the kinetic energy of the whole
object, and the momenta of all the particles, vector summed, is the
momentum of the object.
Ask yourself the question "How does a photon propagate?". It clearly moves
through space, apparently continually "pushing off" (reacting) against space
time (the vacuum/aether if you prefer) itself, just as in the case
of a wave in
water, the molecules react against one another.
Eek! My bogosity alarm just exploded, couldn't handle it. You can
think like this if you wish, but, remember, this isn't physics as we
know it, at all. Reacting or pushing against the vacuum? Remember,
it's all space, it's all fields. If there is action, there is
reaction. If there is momentum created in one direction, there is
momentum created in the opposite direction. In what? Well, here, in
space itself. Right? But wait a minute! What does the "momentum" of
space mean? We can define the momentum of a mass, or of an
electromagnetic wave, but the momentum of space?
Now suppose that this device makes use of that reaction force
between the photon
and the vacuum (virtual particles from the vacuum, if that's your thing), to
"get a grip" on the vacuum.
Yeah, that's what I thought. That's how one can imagine a
"reactionless" drive working. Except that it's a trick. It's not
reactioness at all, it's acting on space, which, to be acted upon, must react.
Though this "grip" may be tiny, they amplify it by
using resonance, i.e. some part of it is multiplied by the number of
times that
the energy bounces back and forth before being lost as heat. Momentum is
conserved, because it is shared with the vacuum, essentially with the whole
universe (and maybe more, depending on your definition of universe).
Absolutely. Which is why we can be quite sure that Shayner is running
a con. Talk about spooky action at a distance! Grabbing the universe
and accelerating it, cool idea. Of course, it's really big, so you
wouldn't perceive the acceleration of the universe, you would just
feel your own acceleration. Note: fixed frame of reference, relative
to the center of mass of the universe. What is your velocity with
respect to that center of mass?
>It's a bit depressing to see the arguments defending the emdrive.
In my previous post I wasn't really trying to defend it, just trying
to explain
what I thought Shawyer was saying.
This post OTOH is more of a defense. BTW last time that this device
was a topic
of conversation on Vortex I was on the side of the prosecution. I can see both
reasons why it may work, and reasons why it might be unlikely to.
The real proof
of the pudding is in the eating. IOW all our arguments are pretty much
irrelevant. It either works in practice or it doesn't.
Put the thing in a weightless environment (preferably in a vacuum), fire it up
under it's own power, and see what happens.
Sure. However, from the arguments and evidence Shayner presents,
there isn't any reason to think it would do anything at all, and
really doing that experiment to eliminate all possible interactions,
no matter how small, would be quite difficult. Read "expensive."
His explanation depends on his being able to dismiss the effect of
the radiation on the side walls as "negligible." Okay, *how*
negligible? Remember, the net force that he *calculates* --
supposedly -- is very small compared to the energy he's pumping into
that cavity.
>I've said, if someone has developed a method of reactionless force,
>which is what the emdrive claim is, boiled down, and has demonstrated
>it, there would be enormous implications to basic physics, and,
>indeed, conservation of momentum is violated.
It's only "reactionless" in the sense that there is no reaction mass. That
doesn't necessarily mean that it isn't pushing/pulling against "something".
Sure. But he does in fact posit that it isn't pushing against
something. If it's generating microwave energy and kicking it off in
one direction, that's pushing. Against the microwave photons,
basically. Momentum imparted to emdrive vehicle equals momentum
imparted to microwave radiation, or any kind of radiation.
He is *not* positing that he's pushing against space. He's really
running a variation on the Dean drive scam, which I remember as a
teenager, I used to read Analog, even before it was Analog.
>Just take two
>snapshots: the situation before the emdrive is turned on, and the
>situation after it is turned off. Conservation of momentum is with
>respect to a particular non-accelerated frame of reference, and with
>respect to any contained system, any "black box" that is not
>absorbing or radiating anything, or where the radiation is balanced.
>Soppose we arrange the emdrive and power source a faraday cage inside
>a sphere, such that the temperature of the sphere is uniform (done
>with heat-sinking and radiation inside the sphere), and the sphere is
>of uniform material. Likewise the environment is arranged to be
>uniform in radiation pressure against all sides of the emdrive sphere.
>
>This is all done in free fall in deep space, so that gravitational
>fields are uniform. So the emdrive-sphere starts in the center of our
>experimental space, no connections or contacts or interactions between them.
>
>In our frame of reference, the experimental space, the net momentum
>of the emdrive sphere begins at zero. The emdrive has a timer which
>turns it on for a period then shuts it off, and the internal
>components settle to zero motion (except for heat). What is the net
>momentum of the emdrive sphere? If it is not still zero, then
>conservation of momentum has been violated.
See above.
>
>Yet Shawyer claims that conservation of momentum is not violated. He
>is obviously contradicting his claim of acceleration!
No, see above.
If it ends up accelerated, to conserve momentum, something was
accelerated in the opposite direction. Emission of photons counts.
So, are photons emitted? He essentially claims, no.
>
>> If we assume that the energy that goes into
>>propelling the vehicle is converted into kinetic energy (of the
vehicle), then
>>the *power* required is the time differential of kinetic energy i.e.
>>d(1/2*m*v^2)/dt. This is d(1/2*m*v^2)/dv * dv/dt, i.e. m*v*a (where a =
>>acceleration).
>
>If we assume that pigs are fishes, then we can all breathe water.
...only if we are pigs. ;^)
Yup. Mammals, essentially.
>Kinetic energy of the vehicle exists in our ("stationary") frame of
>reference. If the vehicle accumulates kinetic energy in our frame,
>then, sure, this energy must have come from some source, presumably
>the power source inside the emdrive system.
I believe that is what the inventor is claiming.
He has the force that is causing the acceleration come from within
the accelerated object. What is the agent of this force, and what is
it acting on? As to theory, he calculates radiation pressure on the
two sides of his cavity, and he calculates that the integrated
pressure over the surfaces differ, predicting in his demonstration
model This is a math problem, and how accurate is the math? The real
key is the pressure on the sides. That's where, I believe, the math
gets hairy. Further, what is the exact pressure on the ends?
>
>Now, imagine a larger black box, it encloses our frame which encloses
>the emdrive system. Call our frame the "room," perhaps it's a space
>station experimental lab. And there is a hole in the wall of our lab.
>And the emdrive shoots out that hole. What happens to the lab? Does
>the lab move in the opposite direction?
No/yes, because the reaction is shared with the vacuum itself, not
just with the
lab. IOW the lab does move, but only in as much as the universe as a whole
moves, which is to say immeasurably small. Though I guess this does raise the
issue of the speed with which the reaction force can be transmitted
through the
fabric of spacetime.
It raises the question of action at a distance, and without any
intermediary agency. No photons. If he creates a magnetic field, and
this interacts with the magnetic field of the earth, then we have
action/reaction. The emdrive would get a shove in one direction, and
the earth would get a shove in the opposite direction. The kinetic
energy increase of the emdrive and the kinetic energy increase of the
earth would be equal, the momenta resulting from this would be equal
and opposite, in a frame which includes the earth and the emdrive.
Is he creating a field that can interact with the environment? He
could be. Think of that air bearing as the bearing of a compass
needle. He turns the thing on, it rotates a distance, it turns it
off, it stops rotating. But if the bearing was frictionless, it would
not stop rotating when he turned it off. Suppose instead of an air
bearing, he has it suspended from the ceiling by a rope. Get it
rotating as fast as the video shows, would it stop as quickly as he
shows in the graph? You would not see that curve. Something is
actively deaccelerating it. What?
Most likely, my guess, if the whole thing isn't fake, is that it's
the pump and the water circulating in the cooling system. Turn the
motor on and the emdrive will rotate. But this could be ruled out if
the cooling system were always on. Other sources for suspicion would
be the cables providing power.
>Regardless of internal
>mechanism, in the larger frame, we have a object, the lab, which has
>ejected a bit of mass.
No, the lab didn't "eject" the "bit of mass" i.e. there was no force acting
purely between object and lab as there would have been had there been e.g. an
explosive release of compressed gas between the two.
From the outside, we don't see what happened between the large
object and the mass that flies out of the opening. What we know is
that there was this "craft" sitting there, not moving, say it's on a
frictionless surface, we don't know what's going on inside. Maybe
there is a gyroscope in there spinning madly, and this object was on
it, and the thing broke apart, flinging the object out (the
"emdrive") Or maybe the emdrive was "flying under its own power" My
question is what happens to the "lab." Does it remain still or does
it recoil? You are saying that there is no force acting between the
emdrive and the lab. Fine. That's a reactionless drive (unless the
force acting on the emdrive is reactive to force from something
outside the lab, or a field that includes the lab).
Shawyer is redefining fundamental physics, *really* fundamental
physics, based on? A very unclear and inconclusive "demonstration,"
performed after years of work and some significant funding. Dean
demonstrated the Dean Drive. People saw it reduce its own apparent
weight on a scale. He convinced lots of people, in fact. The force he
"demonstrated" was substantially larger than what Shawyer is claiming.
I'm not exactly claiming impossibility. Our understanding of the laws
of physics can be defective. But what I keep pointing out is that he
isn't claiming some new physics or some new effect, he's claiming
that traditional physics applies, though he then does some
hocus-pocus with relativity.
Every force has two ends. In this case one end is connected to the object,
however the other end is connected to the fabric of spacetime
itself, not to any
particular object.
Great. Nice trick if you can pull it off. Notice he's not claiming
this. At all. Nor is it necessary to postulate this to explain his
experimental results. If there were a solid experiment, one not so
full of obvious possibilities and mysteries (i.e., the exact nature
of the demonstration), then perhaps speculation about such a thing
would be appropriate.
Suppose Fleischmann had found excess heat as weakly as this? Would we
be worrying about what could possibly explain it? Only when the
experimental results, ones that appear to open the door to a major
revision of thinking, rise out of the noise, clearly, is it
worthwhile going there.
[...]
In this case I thinks it's more a matter of a force between an object and
literally *everything* else. Consider two hockey pucks on the ice. One of them
could move by pushing off against the other (which is essentially the only way
we know), or one could hammer a nail into the ice, and push off against that
(while the other complains bitterly about breaking the rules ;^). If
this device
works at all, then I suspect it is by hammering a nail (or at least a small
tack) into the ice.
Right. In which case it is not reactionless, it is reacting on a
field or the ether or something like that. So there is, then, kinetic
energy in the ether. What the hell does that mean?
>A system can't push itself, and, to my knowledge, no
>exception is known at any scale. He's claiming an exception, based on
>some very shaky math and a very shaky experiment, with very little
>detail provided and, given the length of time involved, very little
>publication and no independent confirmation of even his small
>reported effect. And the experimenter is a microwave engineer who
>would not necessarily have any expertise in or experience with
>calculating radiation pressure.
All good reasons why this may not work.
Essentially, there is no reason to expect that it would work, nor
that he has demonstrated that it works. And strong reason to be
utterly skeptical. His experimental results, such as he has skimpily
reported, don't seem to support his conclusions. He's got practically
nothing to show, yet he is already anticipating progress way beyond
this level, with confident predictions of much higher forces being developed.
>Consider this: in the waveguide, microwave energy is being reflected
>back and forth. There will be pressure against the walls of the
>guide, all the walls. normally, the pressure inside a cavity will be
>equal, unless there is an outside force acting (such as gravity,
>which would increase the pressure at the bottom and decrease it at
>the top, generating a force equal to that of gravity on the contents.)
>
>He claims that the pressure on the sides of the waveguide or cavity
>can be neglected.
This bothers me too, and was actually the basis of my previous objections, and
I'm afraid I don't really understand his explanation of why this is
not a valid
objection, though I get the sense that it has to do with the change in
refractive index due to the introduction of a dielectric into part of the
device, which apparently removes the symmetry.
Hocus-pocus. His explanation was designed to not be understood.
That's what has led me to the conclusion that he's running a con. If
he really was a "brilliant scientist" or even "brilliant engineer,"
he'd be able to explain much more clearly. Instead, it appears to me
with increasing clarity, his explanations are designed to confuse. He
deflects a valid objection by introducing yet another mystery, yet
another unclarity that makes the understanding of the system more
complex. Conservation of momentum is easy to understand, and from it,
you can make exact calculations. If the cavity is closed, energy is
not emitted from it as radiation except as heat (which, by the way,
could provide some thrust if the surfaces of the cavity don't radiate
equally, that's "reaction" from the emission of radiation), then
conservation of momentum tells us that no matter what hocus-pocus
happens inside, the center of mass of the cavity won't accelerate
unless an external force acts upon it. It could *move*, but only by
shifting matter inside, and, by the same token, it could move a
*tiny* amount with radiation inside, but that movement would not only
be tiny, it would also be very rapidly oscillatory. It's really the
same as with moving matter about inside the craft. The center of mass
remains inertial, no accelerating, but the outside will move. It
can't move, though, more than the internal cavity size, i.e, the
interior space where the mass could move about. (Imagine, as a limit,
a very large mass that's contained internally. A little piece of a
neutron star, eh? You shove against this piece and that moves the
piece not at all. But it looks like it does, inside; what you are
moving is the craft, and the maximum distance you can move it this
way is from one end to the other, so your craft would move just that
far as seen from the outside. So ... if the craft moves more than
that, and if we could know that nothing has been emitted and there
are no field interactions, then we do have something outside normal
physics going on.
That this object rotates a little distance on an air bearing, showing
odd behavior no consistent with steady thrust, quite simply, isn't
impressive. I can think of experiments that would be much more
impressive, if the cavity does develop thrust, even if the thrust
were as small as he states.
>Now, look at a photon, and let's suppose Q is
>infinite, the walls of the cavity are perfect reflectors. Now
>consider a microwave photon, it has momentum. It is reflected from
>the side, a glancing blow (i.e., low-angle reflection). This will
>create a force on the side. If the side is oriented in the direction
>of the photons, this pressure would be minimal, but that would imply
>that the cavity is the same size at both ends (assuming the ends are
>parallel planes).
That was my argument exactly, last time around.
And you were right then. What I'm pointing out is that Shawyer's web
site and papers are patent blarney. If someone has a coherent theory
that is unconventional, fine. Then he deserves a chance to prove it
through experiment, or at least experimental design. If someone has
an experiment with anomalous results, inexplicable without a major
revision of conventional wisdom, then, fine.
Shawyer has neither of these. He has a bogus theory that he claims
predicted a tiny effect, not reliably measured. How did he calculate
the thrust? Where was the center of mass of his emdrive system, it's
a damn complicated thing, with all kinds of stuff on it that has no
discernable purpose.
>Shawyer seems to assume constant radiation pressure
>per unit area, but neglects the sides, so, of course, he ends up with
>a net force in the direction of the larger area. In fact, if somehow
>"friction" with the sides were avoided, if the waves or photons could
>be conducted with no pressure on the sides, the pressure per unit
>area on the smaller end cap would increase. Such that there is no net force.
>
>More likely, there is some of both effects taking place; there is
>pressure on the sides, and so there is a force acting on the sides
>that partially balances out the force acting on the large top endcap,
>and there is increase of pressure on the smaller endcap; my guess is
>that the latter could be a small effect. If I imagine water waves,
>focusing the wave on a small area could increase the pressure, indeed.
>
>There are many possible explanations for some force to be detected in
>Shawyer's demonstrated; any time you have a large mass and lots of
>power, relatively subtle effects that might ordinarily be disregarded
>or considered negligilbe, can be seen if you start to make very
>subtle measurements. Dean drive. The effect of vibration on
>scales.... Heat and effects on air....
...more good reasons.
And in the absence of any reason to think that this thing does
*anything* but eat power and burn out klystrons, and jiggle a little,
given that it has lots of stuff going on, I'm wondering why I wasted
all this perfectly good time even considering the thing.
Remember, I thought, at first, that it was a really good joke,
perpetrated by some students. Perhaps assigned by their teacher as an
exercise in creating blarney that would convince someone unwary that
it was a real explanation.
Hey, the way that cold fusion works is that, because of the special
conditions in the palladium matrix, the normal fusion branching ratio
is suppressed and only the helium pathway remains; the excess energy,
because of the confinement of the deuterium, considered as a quantum
system, is transferred to the lattice instead of being emitted as
gamma radiation. The fusion takes place because the Coulomb barrier
is shielded by the conduction electrons in the lattice, which are
specially attracted by the deuterons as they approach, so the
electrons pull the deuterons together.
Now, where's my Nobel prize?
I simply waved away the objections! What really is happening may
resemble *some* of this explanation, but it was blarney, at least
substantially.
Turns out, though, that my understanding of Takahashi's theory -- and
apparently the understanding of those who also commented here in
response to my first questions on Vo -- was missing something. Yes,
Takahashi predicts, from the formation of the Tetrahedral Symmetric
Condensate, the formation of Be-8, which decays into two alpha
particles plus 47.6 MeV or so, but I, and apparently others, had
jumped to the conclusion that this would be two alpha particles with
23.8 MeV of energy. No, that's not what he predicts. The Be-8 nucleus
rapidly decays, all right, but the process is not directly to alpha
particles; rather the excited nucleus emits photons which are
absorbed by the lattice, in a series of transitions, before ending up
with two alpha particles with as little as a few KeV. A whole range
of energies would be expected. I forget the numbers. See his lecture
from ICCF in Rome this year.
We have experimental fact, unexplained: excess heat that is
consistent with deuterium fuel and helium ash. Hence it's reasonable
to put great effort into developing theory that could explain it.
Originally, there was careful work by Fleischmann on the calorimetry,
and add in the (erroneous) neutron reports, there was reason aplenty
for people to investigate, and investigate they did. With Shawyer's
work, there isn't yet any reason to even investigate.
>
>But, with the emdrive operating, does the acceleration we experience
>(which is precisely equivalent to the "force" acting on our emdrive
>system) decline with velocity? If so, we now have a means of
>detecting absolute motion.
You mean this doesn't happen when you drive a car? Isn't it harder
to accelerate
from 50 to 60 than from 10 to 20? If not then please explain where I
screwed up.
(Ignore the fact that friction increases with velocity).
Neither is hard, I just press on the gas pedal a little harder. Isn't
that what makes the car go? Because the gas pedal is hard and my seat
is soft, the pressure of my foot on the gas pedal more than balances
the pressure of my back against the seat, so the car accelerates.
With a constant mass and a constant force, acceleration is constant.
If the emdrive were to work, the difference in pressure between one
side and the other would not vary with the externally observed
velocity of the vehicle; if it did vary with that velocity, then we
would be violating the invariance of the speed of light -- unless
someone can propose some other mechanism for the velocity to affect
the internal operating conditions of the klystron and cavity. So the
felt acceleration would be constant, it would not decline with
velocity. No, it isn't "harder." The "push" is the same.
Suppose you have some rocket bottles. The have enough fuel in them
such that when they burn, you will go from 0 to 10 mph. (and neglect
friction, fine, and you are sliding on ice, not rolling with inertia
in the rotating wheels). Fire another four bottles, you will be at
50. One more, 60. It's the same. (If we can neglect the weight of the
fuel in the bottles. If we count that weight, it gets easier, not
harder, because there is less mass.)
Did you screw up? I don't know. Maybe I screwed up. It is always one
of the possibilities.
