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Action without reaction

  1. Jan 14, 2008 #1
    Here's an apparent violation of the action and reaction law:

    [crackpot link deleted]

    How can it be? Surely EM waves exert forces on objects all the time, nothing new to action without reaction (EM waves are not like sound waves where there is a medium and the medium experiences the reaction).

    But then, all forces in the universe have a delay between action and reaction, because there is always a distance between the interacting charges or masses or whatever it is for the strong and weak nuclear force.
    Last edited by a moderator: Jan 15, 2008
  2. jcsd
  3. Jan 14, 2008 #2


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    Staff: Mentor

    There is no convincing evidence that ion lifters don't just accelerate ions in the air. I'll wait for discussion with the other mentors, but I consider this a crackpot idea.
  4. Jan 14, 2008 #3
    Alright but wait a sec, I think this page was not intended to prove that his flying machine exhibits antigravity, just that EM forces can occur without a simultaneous reaction.

    It happens all the time, EM waves arriving to a radio receiver exert forces to the electrons in the antenna. These electrons experience force without simultaneous reaction.
    Last edited: Jan 14, 2008
  5. Jan 14, 2008 #4

    Ben Niehoff

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    This paradox is resolved by assigning a "hidden momentum" to the EM field itself. This can be done in a consistent way such that momentum is always conserved (i.e., whatever momentum you put into the fields, you can get back out of them again).

    Note that since the electrons experience forces, they must accelerate. And since they must accelerate, they must radiate. I think calculations of the photons thus radiated would show that they carry away momentum that balances whatever is gained by the CM of the electron-electron system. Thus, any thruster designed on this principle would work by means of shooting photons out the rear.
  6. Jan 15, 2008 #5
    Apparently the lower foil is not connected to anything! :rolleyes:

    Only the upper wire is connected to high voltage.

    How can there be continuous current, charge flow, if the circuit is not closed?
  7. Jan 15, 2008 #6


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    Staff: Mentor

    Whatever direction he wants to introduce it from, it doesn't matter. It's still a violation of conservation of energy.
    Not true. EM radiation has to be emitted by something, so the reaction force is on the object emitting the radiation. This is the principle by which a solar sail works.

    Thread locked, crackpot link deleted.
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