Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

White space drive & casimir cavities?

  1. Dec 29, 2012 #1

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Had this directed to my attention:
    How NASA might build its very first warp drive
    I'm guessing the popular science press is overhyping again.

    I see a brief mention in the article about "negative vacuum energy" and the possibility of "Casimir cavities" being "a way forward" ... which seems to be the extent of the physics mentioned.

    Isn't "negative vacuum energy" a form of unobtainium?

    I did see this discussion of energy densities re Casimir effect.
    I just know people are going to ask me about this - so discussion welcome. What is White on about? What is he actually doing at NASA?
  2. jcsd
  3. Dec 30, 2012 #2


    User Avatar
    2017 Award

    Staff: Mentor

    The casimir effect allows to get energy densities below the energy density of the vacuum. If the energy density of the vacuum is 0*, this corresponds to a negative energy.

    *it has to be some very small value, otherwise the expansion of the universe would look different.
  4. Dec 30, 2012 #3

    George Jones

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  5. Dec 30, 2012 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    "one may be tempted to denote these geometries as 'exotic' solutions of the Einstein field equation, as they violate the energy conditions and generate closed timelike curves"
    -- Francisco S. N. Lobo: arXiv:0710.4474v1 [gr-qc]

    One may indeed :)
    (actually quite a neat overview - thanks)

    I'd imagine that having one leg of a Michealson Morely Interferometer through a Casimir cavity (the only experimental evidence mentioned) would produce a fringe shift. We would normally treat the vacuum energy as zero when we use the Einstein equations wouldn't we? Of course it isn't - so how firm is the idea that the Casimir effect produces the kind of "negative energy" that we would otherwise associate with exotic matter distributions?

    Meantime - reading references....
    It still feels like spin-doctoring to me.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook