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Null energy condition

  1. Jun 14, 2005 #1
    What is null energy condition?
    I'm not sure whether this is the right forum to post but I come across this word when reading article about wormholes.
  2. jcsd
  3. Jun 14, 2005 #2


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    The null energy condition means that:

    [tex]T_{\mu \nu} A^{\mu} A^{\nu} \geq 0[/tex]

    With A a null vector. For a perfect fluid, it can be proven that this implies:

    [tex]\rho + p \geq 0[/tex]

    I think that for [tex]\inline{\rho > 0}[/tex], the violation of the NEC is equivalent to a violation of the DEC (dominant energy condition). A perfect fluid that violates the DEC has faster than light effects, see https://www.physicsforums.com/showthread.php?t=78361
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