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Tapping the Zero Point energy

  1. May 2, 2008 #1
    Much ado has been made about using the ZPE as a source of unlimited energy. The Casimir effect between two plates being the quintessential experiment proving the plausibility of such claims. I recall months ago that physicsweb.org reported an experiment that found that the effect could even be used to move the plates apart, not just together.

    Considering such experiments, one wonders if the ZPE could actually be used as an alternative energy provider. One must also wonder then, given the convervation of energy laws of the Universe, what effect our 'tapping' of said ZPE (if at all possible) would have on the Universe. Clearly the effect would be negligible at best, but still I think its interesting to consider what effect it would have.

    Furthermore, I am curious if there has been any theory linking the ZPE to Dark energy? If you will be so kind to indulge a philosophical whim of mine, is it possible that 'tapping' the ZPE would in turn diminish the Dark energy, and consequently hinder the Universe's current accelerating expansion? Please forgive me if this last question is too sci-fi for this forum, merely think of it as an interesting thought, if not purely in the imagination.
     
  2. jcsd
  3. May 2, 2008 #2
    I think the ZPE would show up more as a cosmological constant than dark energy.
    In the absence of gravity, there's no real issue of energy conservation, so you would have a hard time "tapping" it as an alternative energy source.

    With gravity in the mix, you'd have a hard time tapping it as an alternative energy source within your local region of space.
     
  4. May 2, 2008 #3
     
  5. May 2, 2008 #4
    The cosmological constant reflects the energy in "empty space". It's a GR thing.
    By the absence of gravity I mean (a) if you try to answer your question most basically, the zero point energy is a quality of quantum field theories and makes no reference to gravity. So we should be able to answer your question in that context without using gravity. Or, (b), where gravitational effects are negligible. In other words, over distances small compared to the curvature of spacetime.

    A more complete theory of gravity + quantum mechanics would probably add some twist to this, because as it stands, the zero point energy is actually a huge, huge number. One way to make it zero, or approximately zero, is through supersymmetry, or approximately broken supersymmetry. But unless you can make the ZPE small, you have big problems. Because gravity couples to all forms of energy, having enormous amounts of energy in the vacuum leads to bad things.
     
  6. May 6, 2008 #5
    ZPE is the same force (or energy) that moves electromagnetic waves through space, and electron around nucleons, right?
     
  7. May 6, 2008 #6
    time to close this discussion
     
  8. May 6, 2008 #7
    delete.. nevermind, the post is gone
     
  9. May 6, 2008 #8
    Aaah, much better. The zero point energy is the energy of the ground state of the harmonic oscillator, which one finds to be non-zero. Actually, since only relative energy measurements are meaningful, and not absolute ones, it gets a bit tricky.

    But for something like electromagnetic radiation in a cavity, versus electromagnetic radiation in vacuum, the oscillatory modes have different zero point energies and this difference can be measured via the casimir effect.
     
  10. May 6, 2008 #9
    Still no one has answered the question. Can zero-point energy, in principle, be used as an unlimited energy source, and why/why not?
     
  11. May 6, 2008 #10
    This is probably what Nikola Tesla considered to be the "wheel works of nature".

    Where does zero point energy show up in nature?
     
  12. May 6, 2008 #11
    To answer both questions, you can't use ZPE as an unlimited energy source, in the present framework of physics, and the present framework of physics is where ZPE is discovered. Within that framework, things like conservation of energy and thermodynamics apply, and those things say you can't get something from nothing.

    The energy is there, but unless there's a lower well for it to go into, there's no extracting work from it.

    To the second question, already answered, is that ZPE shows up in the Casimir effect. A quick wikipedia-ing will dig that up.
     
  13. May 6, 2008 #12
    I suspect that real particles are created out of the zero-point-energy. And when real particles are created, this causes the gravitational field to intensify which has the effect of hindering further production of real particles. So you could only get so much energy/matter out of the ZPE before the region produced a black-hole.
     
  14. May 6, 2008 #13
    Well, ok, I do realize that the laws of QM depend on CoE, and CoE says you can't get something from nothing, but that's not really a proof.

    Also, I asked in another thread hoe ZPE doesn't violate CoE in the frame of a relativistic observer. If the idea is "if it exists for less than a Planck time, it's ok", then if I'm, say, buzzing past the Earth at .9999c, from my perspective the particle that exists for a Planck Time on earth and hence doesn't violate CoE actually exists for quite a bit longer, and therefore something from nothing actually did pop out of the vacuum.

    Where's my mistake?
     
  15. May 6, 2008 #14
    You're better off asking that question in your own reference frame. Anyway, ZPE and "virtual particles in the vacuum" are slightly different processes and you should distinguish between them. ZPE refers to the ground state energy of a non-interacting (or weakly interacting) quantum field, whereas virtual particles depend heavily on interactions and are described as 1-loop Feynman diagrams.
     
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