Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
I think this would be a great thing to not do.

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.



Electron Propulsion

Involving a mystery associated with curved electron beams
  [vote for,

Many years ago I encountered a paper-magazine article in which Person A described an idea, which others said, "That won't work because ..." --and then Person A took that objection and turned it into a paradox. I never found the solution to the paradox, and I've long since forgotten the name of Person A. However, because the Idea is not widely known, and also because I came up with a slight modification of the paradox, here:

. . . . . .
. . . . . .
. . . . . .
^ . . . . .
e . . . . v
The above set of dots is supposed to represent SOME of the "lines" 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 the field-lines.

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- arrow) is located. What Person A originally came up with was an idea that depended on the assumption that if the electron "acts" by curving one way, the overall magnetic field --or at least the source of it-- 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 curves around and impacts at the location of the "v" (which is cool, because in Space you don't want to accumulate an electric charge on your space-ship), there is ANOTHER transfer of Momentum, as 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 think of the magnetic field as circular, and this sketch cross- sectioning 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 of electron guns around the "ring" of the magnetic field.)

So, do we ACTUALLY get propulsion ONLY from the bremsstrahlung? Or do we actually get the double-tap of Momentum as each electron leaves, and then curves back to impact? Maybe we get BOTH?!!

Finally, what if we used proton guns instead? The double-taps would be greater, and the bremsstrahlung would be less!

Vernon, Jun 03 2015

Bremsstrahlung http://en.wikipedia...wiki/Bremsstrahlung
As mentioned in the main text. [Vernon, Jun 03 2015]

News Item http://www.newscien...t.html#.VWxezbzOjRk
This news item triggered my remembering of that old paradox, since it involves electrons leaving a spacecraft. [Vernon, Jun 03 2015]

Mechanical Electret Magnet Mechanical_20Electret_20Magnet
As mentioned in an annotation. [Vernon, Jun 04 2015]


       I have an incomplete understanding of the physics involved, but:   

       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, Jun 03 2015

       [MechE], thanks, but what of the propulsion Questions/Possibilities in the Idea? Is there any other propulsion besides the action/reaction of bremsstrahlung?
Vernon, Jun 03 2015

       Poo, [MechE] beat me to the answer.   

       That was too easy. Set us a hard perpetual motion or reactionless drive challenge, at least!
pocmloc, Jun 03 2015

       There is a fundamental error in the reasoning behind this idea.   

       Once I've read it, I'll figure out what it is.
MaxwellBuchanan, Jun 03 2015

       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?
cudgel, Jun 03 2015

       " There is a fundamental error in the reasoning behind this idea. Once I've read it, I'll figure out what it is "   

normzone, Jun 03 2015

       I would suggest two things, of which 0, 1 or 2 may be true.   

       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, Jun 03 2015

       [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.
Vernon, Jun 03 2015

       [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.// [marked-for-tagline]
Vernon, Jun 03 2015

       so where does the idea, that a magnetic field will not be affected while it's bending the path of an electron, come from ?
FlyingToaster, Jun 03 2015

       From the Mind of [vernon]?
pocmloc, Jun 04 2015

       [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" part 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.
Vernon, Jun 04 2015

       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.
wjt, Jun 04 2015

       Rather than moving through space, why not just move the space around you like the Dark Matter drive aboard the Planet Express ship?
Duck Lagrange, Jun 04 2015

       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 situation.   

       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 magnet.   

       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.
scad mientist, Jun 04 2015

       So, what Vernon has described here is not a reactionless drive, but driveless reaction?
MaxwellBuchanan, Jun 04 2015

       [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 happens.   

       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 the numbers!   

       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".   

       Thank you.
Vernon, Jun 04 2015

       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.
scad mientist, Jun 05 2015

       What is the potato-on-a-string equivalent of bremsstahlung radiation?
pocmloc, Jun 05 2015

       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 potatoes.
scad mientist, Jun 05 2015

       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?
pocmloc, Jun 05 2015

       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.
WcW, Jun 05 2015

       //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, radially.   

       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.
MaxwellBuchanan, Jun 05 2015

       The water should be carbonated, the CO2 will be released when the water hits the ground, the plant's will like that.
bs0u0155, Jun 05 2015

       That explains why carbonated beverages are so popular with couch potatoes.
MaxwellBuchanan, Jun 05 2015

       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.
wjt, Jun 05 2015

       The secret is in the spinning fields.
WcW, Jun 06 2015

       Relevant tagline:   

       // This is what happens when one confuses "random" with "profound." //
notexactly, Jun 14 2015

       [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.
wjt, Jun 16 2015

       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. [+]
Voice, Jun 17 2015

       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.)
pashute, Sep 27 2023


back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle