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Many years ago I encountered a paper-magazine article in
Person A described an idea, which others said, "That won't work
because ..." --and then Person A took that objection and turned
into a paradox. I never found the solution to the paradox, and
long since forgotten the
name of Person A. However, because
Idea is not widely known, and also because I came up with a
modification of the paradox, here:
. . . . . .
. . . . . .
. . . . . .
^ . . . . .
e . . . . v
The above set of dots is supposed to represent SOME of the
of a magnetic field passing through your screen (toward you and
away from you). The "e" is an electron, and the "^" symbol
indicates the initial direction of the electron's motion, across
It is well-known that in this situation the electron's direction of
motion will become curved, as it interacts with the magnetic
field --perhaps it arrives back where the letter "v" (a down-
located. What Person A originally came up with was an idea
depended on the assumption that if the electron "acts" by
one way, the overall magnetic field --or at least the source of
should "react" by rotating, thereby balancing the Action.
Person A was told that no such reaction occurs. Perhaps the
reaction is actually accommodated by the "bremsstahlung"
radiation emitted as the electron's path curves through the
magnetic field (see link). However, here is the Paradox:
Look again at that ASCII sketch above. Consider the electron
"gun" that shoots that electron into the magnetic field. We are
doing this in Outer Space, and the gun is attached to the space-
ship. There will be Action and Reaction with respect to the Law
of Conservation of Momentum, as the electron goes one way and
the gun (and ship) goes the other. Well, when the electron
around and impacts at the location of the "v" (which is cool,
because in Space you don't want to accumulate an electric
on your space-ship), there is ANOTHER transfer of Momentum,
the electron is absorbed. This transfer ALSO causes the ship to
move in the same way as when the gun fired!
The NET result is that the ship appears to be moving
reactionlessly! What is the solution to that paradox?
Meanwhile, here is my modification, which DOESN'T CARE if the
magnetic field tries to rotate or not:
. . . . . . _ _ _ _ _ _ _ _ _ _ . . . . . .
. . . . . . _ _ _ _ _ _ _ _ _ _ . . . . . .
. . . . . . _ _ _ _ _ _ _ _ _ _ . . . . . .
^ . . . . . _ _ _ _ _ _ _ _ _ _ . . . . . ^
e . . . . v _ _ _ _ _ _ _ _ _ _ v . . . . e
Ignore the horizontal lines, which are there only to show the
separation of two sets of magnetic field lines. You need to
of the magnetic field as circular, and this sketch cross-
it, with the field going into your screen on one side, and coming
out of your screen at the other side --and going back in again at
the first side.
Thus we can fire two electron guns, and the electrons in both
beams curve in a BALANCED way, and we STILL get the double-
Action of space-ship propulsion! (We can actually mount a lot
electron guns around the "ring" of the magnetic field.)
So, do we ACTUALLY get propulsion ONLY from the
Or do we actually get the double-tap of Momentum as each
electron leaves, and then curves back to impact? Maybe we get
Finally, what if we used proton guns instead? The double-taps
would be greater, and the bremsstrahlung would be less!
As mentioned in the main text. [Vernon, Jun 03 2015]
This news item triggered my remembering of that old paradox, since it involves electrons leaving a spacecraft. [Vernon, Jun 03 2015]
Mechanical Electret Magnet
As mentioned in an annotation. [Vernon, Jun 04 2015]
||I have an incomplete understanding of the physics involved,
||I believe the issue is that the magnetic field doesn't
experience a reaction force, but it does induce an electrical
reaction force in the magnet. Regardless, the magnetic field
source does experience a reaction force.
||[MechE], thanks, but what of the propulsion
Questions/Possibilities in the Idea? Is there any other
propulsion besides the action/reaction of bremsstrahlung?
||Poo, [MechE] beat me to the answer.
||That was too easy. Set us a hard perpetual motion or reactionless drive challenge, at least!
||There is a fundamental error in the reasoning behind
||Once I've read it, I'll figure out what it is.
||So, person V, you fire electrons and get a little push.
Whether you get a double push or not, how much energy did
you use up to fire the electrons and why didn't you use that
energy to propel yourself and your ship in another way?
||" There is a fundamental error in the reasoning behind this idea. Once I've read it, I'll figure out what it is "
||I would suggest two things, of which 0, 1 or 2 may be
||First, I am not sure that the electron returning to the
"v" will impart a downward motion to "v". If "v" is
part of the same spaceship that fired the electron,
then it (the v) will have a positive charge on it.
Therefore, as the electron approaches the "v", it will
be attracted to the incoming electron, and will be
pulled upward, not knocked backward.
||[MaxwellBuchanan], remember that the electron,
despite losing some energy as radiation when it curves,
is coming back to the ship with most of its original
energy-of-motion. To the extent that the electron
attracts the ship at point "v" (actually intended to be
something of a down-arrow, while the "^" was
something of an up-arrow), and slows the ship down,
the electron is also attracted, and speeds up. THOSE
two motions balance out as impact happens.
||But where is the balancing-out of the rest of the
electron's momentum, that it had as it finished its
curve? Somehow we would have to imagine that the
magnetic field, in causing the electron to curve, is
pulling the ship backward, by almost TWICE as much as
the ship received in terms of impulse when the electron
gun fired. (The "almost" relates to the bremsstrahlung.)
||After all, the ship is NOT supposed to be able to move in
an overall way if the electron was attached to a rubber
band, and was thrown away from the ship, and got
pulled back. So (discounting the bremsstrahlung) the
ship shouldn't move in an overall way if the electron
comes back courtesy of the magnetic field.
||But that "almost TWICE as much" just doesn't seem very
reasonable to me...and so we might have a paradox, as
mentioned in the main text.
||[cudgel], the answer to your question is, "This is the
HalfBakery, where we don't do things the obvious way."
//Where we don't do things the obvious way.//
||so where does the idea, that a magnetic field will not be affected while it's bending the path of an electron, come from ?
||From the Mind of [vernon]?
||[FlyingToaster], see what [MechE] wrote? The FIELD
doesn't react; the SOURCE of the field reacts.
||Relevant to that is something I wrote in another Idea
recently. Use the third link to see it; read the
introductory stuff, and then skip to the first "variation"
of that Idea. The FIELD is not affected when the source
of the field rotates in the manner described.
||In this Idea, however, the source of the magnetic field
is probably bolted to the space-ship. It is somewhat
circular in shape, and with electron (or proton) guns
equally spaced all around the circumference of that
shape, at least SOME of the forces the magnet-source
would experience are cancelled-out!
||That's why I wrote in the main text, "DOESN'T CARE if
the magnetic field tries to rotate or not". We still have
a mystery, or a paradox, to solve, to keep the "double-
taps" in this Idea from allowing propulsion via a
violation of the Law of Conservation of Momentum.
||Would a yoyo work? Two force vectors, one linear and one spin. The spin would allow the yoyo to return via it's tether. Sorry, the text made me start thinking things that return when thrown.
||Rather than moving through space, why not just move the
space around you like the Dark Matter drive aboard the Planet
||Bremsstrahlung radiation is a bit of a red herring.
Yes, you will produce some radiation and yes this
will theoretically contribute to the total
momentum equation, however the radiation from
this setup will be very low frequency and have
VERY little momentum. I expect it would be
orders of magnitude more effective to provide
your propulsion using LEDs pointed behind you,
which is orders of magnitude less effective than
ion propulsion. Basically, Bremsstranhlung is so
small that it can be completely ignored in this
||The magnetic field in the area shown will change
as the electron passes. It could be considered
accurate to say that the magnetic field produced
by the magnetic doesn't change, however a
moving electron will create a magnetic field of it's
own, and if you measure the magnetic field, it will
be the sum of the field from the moving electron
and the field from the magnet. The magnetic field
from the electron will cause a force on in the
||Assuming the center of mass of the magnet is in
the middle of the first picture and is firmly
attached to the ship, electron gun, and electron
target, the following sequence will occur:
||When the electron is fired, the ship will be
accelerated down (relative to the computer
screen) and start rotating counterclockwise. As
the electron is turned to go to the right, the
downward motion of the ship will stop (reaction
to topping the upward motion of the electron)
and the ship will be moving to the left. Rotation
is not affected much depending on the path of
the electron relative to the center of mass. As
the electron is accelerated to be going down, the
ship will stop moving left and start moving up.
When the electron hits the target, it will stop the
upward motion of the ship as well as the rotation.
||At this point, the ship will have moved ever so
slightly to the left, but the center of mass of the
combined electron/ship system will still be in the
same place. The position in the up/down
direction will be the same as at the start. The
ship will have achieved some rotation. If you
combine two of these as you suggest, you will
eliminate the rotation and slight movement to the
left and now the spaceship will just slightly
oscillate down and up for each pair of electrons
you fire. If you fire a continuous stream of
electrons you can avoid the annoying oscillations
and your ship will remain perfectly stationary.
||So, what Vernon has described here is not a
reactionless drive, but driveless reaction?
||[scad mientist], so you are saying that what I previously
wrote in an earlier annotation, "we would have to
imagine that the magnetic field, in causing the electron
to curve, is pulling the ship backward, by almost TWICE
as much as the ship received in terms of impulse when
the electron gun fired" --that indeed is what actually
||I'm not surprised, but I did say something about feeling
doubtful of the numbers. It's one of those things where
I'd really like to see the experiment performed, to get
||I might mention that I was aware that bremsstrahling
was not a huge factor (but didn't want to ignore it AS a
factor), and that phenomenon would be much less of a
factor if protons were the ammunition, instead of
electrons. Also, I was focusing on individual particles
only to more-clearly present the problem. Obviously, if
the double-taps could work as a propulsion system, we
would want steady streams of particles getting shot
from the "guns".
||I am skeptical that we are saying the same thing
because I fail to see anything mysterious here.
||I guess I do agree that the spaceship is receiving
acceleration in the same direction from both the
firing and catching of the electron. I think this is
what you are referring to as a double-tap.
However the gradual acceleration in the
forward/backward direction as the electron moves
around the curve exactly matches the acceleration
from this "double-tap".
||Replace your electron gun with a potato cannon.
Replace your magnetic field with a string tethering
the potato to a spot half way between the cannon
and the target. On the ship you feel the double
tap of the cannon firing and the potato splatting,
but in between there a half-wobbling in the
opposite direction as the potato swings around.
||What is the potato-on-a-string equivalent of bremsstahlung radiation?
||Well, if you put some negative charge on the potato
and launch it REALLY fast... but as I said above, the
effect of Bremsstrahlung in this application is so
small that it is irrelevant, with electrons or
||Sure but there must be some equally minuscule effect on the potato that we can similarly carefully ignore, such as friction heat loss inside the string from its elastic deformation?
||Also how do you tie the potato to the string? What kind of knot do you use?
||What is this nonsense about fields rotating. Also, the
magnetic source and the electron experience a reciprocal
action, both pulled together, the net gain is zero.
||//What is this nonsense about fields rotating.//
||I've seen rotating fields on aerial photos, especially in
the US. The fields are huge and circular, and have a
horizontal water-spraying arm fixed over them,
||I don't understand how they get the field to rotate,
but it makes sense because every part of the field
passes under the sprinkler in turn.
||The water should be carbonated, the CO2 will be released
when the water hits the ground, the plant's will like that.
||That explains why carbonated beverages are so
popular with couch potatoes.
||I can't see how you can simultaneously throw your
electron and attract it back, whilst moving Vinint to
Vfinal position due to ship move.
||The secret is in the spinning fields.
||// This is what happens when one confuses "random"
with "profound." //
||[notexactly] On the very rare case, the random is profound.
||Then mankind designs, purifies and understands the hell out of it and the very special becomes common place.
||It may be a recipe for lamb stew written in
Swahili for all I know but I'm going to pretend I'm smart
enough to think it works. [+]
||The magnetic force is not the field source.
The reaction is no horse and has no sense of course.
You believe this is an issue of Morse,
and, regardless, electrical fields with no remorse.
The curve that the electron carves through the ship
creates a pointless shape that reminds me of a whip
that finds its way through a nonsensical quip
but may make sense after a sip,
which in the meantime, I'll have to skip.
||The radiating words resonate beyond my own,
reasonably, returning to where they were thrown
while making no sound and reaching the throne
of my sad scientists and other kings of the zone.
Don't ask me what notion I had in mind,
because I may answer your motion in kind
of a mixed-up coffee grind
with Brem's strah lung or anything else I find.
I wish I really understood
what is bad and what is good
but when the planet is hit by CO too
it will be happy, as it should.
And now that all to say has already been sad
coming back to the ship will make me glad
despite the minuscule deformation of lightly clad
Dark Matter in a continuous stationary lamb stew
(which in Swahili spells Bad.)