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Does energy need to be released for spacetime curvature?

  1. Mar 18, 2015 #1
    My question is related to M. Alcubierres paper on the warp drive within general relativity. I was wondering about the realizability of this, setting the three energy conditions aside for the moment.
    Assuming the highest energy density known to me as an energy source, namely something like matter-antimatter fuel cells, is it necessary to actually release the energy in form for instance of annihilation processes in order to obtain curvature ?
    More precisely, how would I implement the stress-energy tensor in this scenario and how does it change between reaction, i.e. annihilation, and the bare storage of matter ?
  2. jcsd
  3. Mar 18, 2015 #2


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    Science Advisor

    The stress-energy tensor is a teonsor on the space-time manifold, so it doesnt' change! Or if you want to be a bit less rigorous you can think that the change is included in it as it is define on the whole space-time.
  4. Mar 18, 2015 #3


    Staff: Mentor

    No. Energy and matter always cause spacetime curvature. But it might not be the kind of curvature you are looking for. The kind of curvature you need for the Alcubierre metric is not the kind that any sort of ordinary matter or energy generates. So it doesn't matter how much ordinary matter or energy you collect; it won't give you what you want. You need what is often called "exotic matter", i.e., something that violates the energy conditions. You can't just fire up the matter-antimatter generator and make exotic matter; there is no known process that will produce it if it's not already present. And there isn't any already present anywhere that we observe. (Many physicists think there can't be any.)
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