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A Universe from Nothing

  1. Dec 23, 2011 #1
    I am sure by now many of you have viewed the "A Universe from Nothing" lecture given by Lawrence Krauss on YouTube or are familiar with its context.

    Much controversy has been stirred up as a result. I am interested in having a few things explained to me.

    1. The term 'nothing' refers to what exactly? A quantum vacuum I believe, but is this true? Isn't a quantum vacuum a sea of energy governed by physical laws and therefore something rather than nothing. Please elaborate.

    2. Quantum Uncertainty. Is this description correct: Pairs of qualities such as energy, position and velocity cannot be exactly determined simultaneously. The more precisely determine a particles velocity the less precisely we know its location, therefore, a particle could be located in more than one position.

    3. We observe virtual particles popping in and out of existence all the time. Where exactly are they coming from? The quantum vacuum? Are there really uncaused?

    4. I read a few articles written by physicists who said its a highly speculative notion that we can take what happens to virtual particles and apply it to our Universe. Is this true?

    If you have any other information that relates to this subject that you would like to add I would appreciate it.

    I realize I put much out there and many of you might prefer not to put in the time to answer my questions. If you could at least take on 1 or two of them I would appreciate this.

    Thanks!
     
  2. jcsd
  3. Dec 23, 2011 #2

    phinds

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    yes that's correct.

    no, it's not that a particle IS in more than one position, it's that you don't KNOW its position until it's measured.

    The most striking example of this is an electron going through a slit in a 2-slit experiment hits the phosphor detector screen at a particular point, BUT at any arbitrarily small amount of time BEFORE it hits the detector, you have no idea where it was and it almost certainly was NOT next to the place where it hit the detector. In classical physics, this is nonsensical. Welcome to the quantum world.
     
  4. Dec 23, 2011 #3
    It refers to the total energy of universe, which in that interpretation is exactly zero, thus the tittle "universe from nothing". It is essentially the case of getting something out of nothing by splitting it to equal and opposite parts, so that they exactly cancel out. Energy in matter and radiation is positive, and energy in gravitational fields is considered as negative. Those two exactly balance out to zero.
     
  5. Dec 23, 2011 #4

    apeiron

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    Yes, even the most extreme versions of "something from nothing" quantum cosmology, like Vilenkin's tunneling wave function story, still need a something that pre-exists. Such, as for example, the laws of physics.

    Vaas did a good overview paper...http://arxiv.org/ftp/physics/papers/0408/0408111.pdf

     
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