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Gravitational waves and negative energy.

  1. Jul 18, 2006 #1
    I was wondering whats the link between gravitational waves and negative energy, i heard that 'in the presence of large gravitational fields, negative energy fields are rather common' from one of michio kaku's book. whats the link between gravitational fields and gravitational waves/ gravity and gravitational waves.
    edit: can negative matter ever fall into a black hole? i don't think they can because theyre repelled by matter but if they did, because they have antigravity, would they reduce the strength of a gravitational field some how antigravity cancelling gravity?
    Last edited: Jul 18, 2006
  2. jcsd
  3. Jul 19, 2006 #2
    I think that was Michio Kaku's "Parallel Worlds", where he was talking about a donkey in a hole. In layman's terms, you have to expend energy to climb out of the hole, so you can view the hole as a negative energy location. Then if you mentally replace the hole with a "gravitational field", you can perceive this as a "negative energy field". Maybe one of the experts will step in here for some precise advise.

    PS: I don't like the word field myself, because we're talking about a location with properties, and "field" tends to assign a physical existence to the properties rather than the thing or region that has the properties.

    PPS: I don't know about negative matter. And I'm not a fan of parallel universes.
    Last edited: Jul 19, 2006
  4. Jul 19, 2006 #3
    yea! a reply
    Im keeping an open mind about all things untill I understand most stuff even the most strangest, wakyest ideas. That's kinda why i didnt mention the title of the book, I know some people won't want to get involved in anything relating to such ideas.
  5. Jul 19, 2006 #4


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    I'm not sure I can tell you anything that you can't find in the book. Classical GR has in the past assumed that there is no such thing as "negative energy" in many important theorems. Quantum mechanical effects such as the Casimir force, and cosmological observations such as "dark energy", suggest that negative energy probably does exist, even though it's pretty weird.
  6. Jul 19, 2006 #5
    My high school physics teacher said something about "gravity being negative energy" but I never fully understood his point. This clarifiess alot. Thanks.
  7. Jul 22, 2006 #6
    If negative matter means antimatter, then it probably has as much inertia/energy/weight as normal matter.. rather than cancelling some of the black hole's mass, it would add to that mass (sure, annihilating with whatever matter it encounters, but only to radiate the equivalent mass-energy.. and since radiation can't escape either..)
  8. Jul 23, 2006 #7


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    Antimatter is not negative matter! So the rest of your statement seems correct.
  9. Jul 23, 2006 #8


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    If negative energy could exist on its own, then it probably could not fall into a black hole. Because negative energy is predicted to be gravitationally repulsive, it should be just as impossible for such energy to enter a black hole as it is for normal energy to exit one.

    However, there is no theoretical way for negative energy to exist except as part of a system which posses a greater amount of positive energy, and that system as a whole could fall in through the Event Horizon.
  10. Jul 24, 2006 #9


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    There's a sneaky point here. If we somehow had a "lump" of negative energy, it would have a negative mass. While it is true that negative mass would be repelled by positive mass, it would also have an inertia equal to minus mv (by the equivalence principle), thus it would move in an opposite direction to the applied force, i.e. it would fall "down" just like normal matter.

    Some forms of "negative energy" do appear to exist (the casimir force, the cosmological constant), but there are not any known sources of "big lumps" of such energy with a total negative mass.

    Negative energy also should not be confused with antimatter, which is expected to have a postive mass just like everything else.
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