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Something From Nothing

  1. Feb 9, 2014 #1
    First time visiting and posting here but I feel there is likely no better place to ask such a question.

    I understand virtual particles can become real particles in empty space that gravity is introduced into. Gravity will lower the net energy of the universe allowing (or maybe forcing) the virtual particles that are popping into existence everywhere to stay a little longer and become real, permenant particles in order to rebalance the energy to zero and make the space stable (if that is an accurate way of looking at it)

    My question is this: would the process of introducing gravity into "empty" space, thus forcing the spontaneous transition from virtual to real status of the present particles, cause an increase in temperature/radiation?

    The reason I ask is because I watched a Krauss lecture and got to imagining the following scenario. A "bulk" in which gravity resides and permeates is where our universe pops into existence and expands within. Gravity, perhaps due to being a "closed string" or whatnot permeates the bulk but also our universe.

    In the early universe there is no positive energy to balance out the negative energy being introduced into it by the gravity within which it is expanding and to compensate matter starts coming into existence. I'm wondering if this might be a viable model but it is untenable with the background radiation however, unless this process produces radiation/heat.

    And if it does it seems like it would lead to the requisite almost uniform distribution of matter. The gas would come out mostly uniform because the virtual particles are everywhere and would transition into "real" status almost uniformly but each individual virtual particle has its own unique random velocity before it transitions so the following real particles would be uniform with but a random assortment of velocities.

    Lastly, an apology as I am not formally educated on these matters, nor do I have a degree of any kind to speak of, and I am sure to most that frequent these forums my views are ignorant. I thank you for your patience and help in setting me straight.

    Last edited: Feb 9, 2014
  2. jcsd
  3. Feb 9, 2014 #2
    Hi Jeff, nice question. My view would be that you would need a lot of matter to be there already for this to work. Gravity is quite a weak force so for the energy to balance you would need a lot of it to create a particle. We talk about the process you describe occurring near black holes, but they are very massive indeed!
  4. Feb 9, 2014 #3


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    Remember that a black hole introduces a gradient in the gravitational field. The larger the gradient, the easier it is for virtual particles to become real. In the very early universe the gravitational field was very very even since large, compact objects hadn't formed yet. So gravity wasn't causing the creation of new particles and anti-particles.
  5. Feb 9, 2014 #4
    The Universe from nothing model doesn't require a large gravity anisotropy such as a black hole. Nor any previous matter. The form of virtual particles created is similar to the false vacuum process. In false vacuum the false vacuum region is the lowest energy state. The true vacuum is the normal energy state ie( universe). The two regions are separated by a barrier of some form. In this models case that barrier is the Higg's field. One particle of a virtual particle pair moves from the false vaccum to the true vacuum via quantum tunneling. This leaves behind one particle which becomes real.

    Another similar process is Parker radiation, which is virtual particle production due to an inflation of the universe. All three models only require two dissimilar regions separated by some form of barrier for quantum tunneling to occur. The earliest particles occur usually through the Heisenburg uncertainty principle or similar quantum processes. A true state in quantum mechanics due to the uncertainty principle will not remain a pure state leading to virtual particle production.
  6. Feb 9, 2014 #5
    I'm sorry Drakkith and Jilang, by stating that I understand gravity can cause virtual particles to become real particles I am not referring to Hawking radiation. I was referring to the fact that the net energy value of space is zero, and if you reduce the energy value of empty space (space filled with no matter, only virtual particles) below zero by introducing gravity, then it will rebalance back to zero by creating matter via the mechanism of virtual particles changing states to real particles.

    The gravity isn't coming from matter within our universe in this model. It is coming from the bulk. The hyphothetical extra-spatially dimensional area outside of our universe that our universe is within. String theorists and even standard model physicists like Lisa Randal work on models such as these, in which case gravity is a closed loop or closed string, meaning that it might not be "attached" to our universe and can freely occupy our universe and the bulk, unlike the other forces.

    So in an early universe expanding in such a gravity-filled bulk, the gravity entering the young, expanding universe would lower its net energy value and cause the creating of matter by yanking it into existence from virtual particles right? And if so, and if this process generates heat/energy...who knows?

    Thank you Mordred, I am not familiar with this Parker radiation and will look into it. It might shed some light for me too.
  7. Feb 9, 2014 #6


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    How can you have gravity if you don't have any energy in space to begin with?
  8. Feb 9, 2014 #7
    Jeet you would be better off studying false vacuum first. Although it lacks aspects needed to be a finalized workable model. Its methods are used in current models. Such as chaotic eternal inflation. The problems I mentioned with the false vacuum is no graceful exit. Once it starts you can't stop it. As well as no reheating phase.

    However the process described from false vacuum leads up to our current models. This makes it a better choice to understand the universe from nothing model.
  9. Feb 9, 2014 #8
    Thank you Mordred I will do that.

    Drakkith. Gravity being tied to matter/energy and resides only within our universe is the common view. Some theoretical models have been proposed that deal with gravity differently. String theory (which I am not a fan of) allows models where the source for gravity is not within our universe but come into it from a bulk that our universe is within. I mentioned Lisa Randal above, and she explained such models that she and a colleague worked on in her book Warped Passages. So to answer your question where would the gravity come from: it would come into the universe from the bulk. Or in the case of a model Lisa was working on, from a nearby brane (separate universe) that is next to us in the bulk.
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