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Effective mass of a system

  1. Jan 1, 2014 #1
    I just want to know, is a technology designed to reduce the effective mass of a system possible, at least in theory?

    Within the system, everything acts as it should (it retains all chemical, physical, and structural properties), but outside, it acts as if it had a lower mass. It's not as heavy, and it doesn't take as much energy to move it.

    I know it's a long shot, but the idea is interesting, isn't it?
  2. jcsd
  3. Jan 1, 2014 #2


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    Violates conservation of momentum. Pick a frame of reference within which this system is moving. It has a certain non-zero momentum. Have it magically reduce its mass. Its momentum has changed without application of any external force.

    If you had a system with a lot of energy and allowed that energy to radiate away, then you could achieve the desired result. Conservation of momentum would be preserved because the energy that you radiate would carry away the lost angular momentum. But at that point you don't have a magic mass reducer any more. You just have a photon drive.
  4. Jan 1, 2014 #3
    Only in science fiction. In fact, your question reminds me of the science fiction / comedy movie "Explorers".
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