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Quantum Foam Clarification

  1. Jun 11, 2008 #1
    Initially I want to let everyone know that I came across these forums recently after searching for further information regarding various topics of theoretical physics, quantum mechanics, etc. and am astounded by the wealth of information here. I am very new to these ideas and am just beginning to grasp all the concepts involved.

    My question is regarding quantum foam. I understand what is meant by the term (to the best of my ability at least). The way I understand it, as we talk about spacetime at a sub-Planck level, the 'smoothness' of it as described by General Relativity is replaced by a turbulent array of particles that crate enough energy (and therefore mass) to curve spacetime in drastic and decidedly 'unsmooth' ways.

    First, is this admittedly simple explanation close in describing quantum foam?

    Second, why does this happen? Is it because as distances get smaller and smaller, the corresponding wavelengths of particles (in the particle-wave duality sense) get shorter and shorter thereby creating more energy and therefore curving spacetime more dramatically?

    Again, this is all very new to me. I was a government/history guy in college, never took any sort of high level physics class. Feel free to rip apart anything I've said.
  2. jcsd
  3. Jun 11, 2008 #2


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    Can you get sub-planck level. I thought any particles smaller than Planck's Length would have so much energy that they are in side a black hole.
  4. Jun 11, 2008 #3
    Everything you say sounds correct. However, as to what happens to spacetime at short distances remains pretty much armchair speculation even by the best minds of our time. Don't believe anyone who says otherwise =)

    There are two reasons to believe that spacetime isn't smooth. One has to do with virtual particles that exist for very short times and have very large energies. If you think of quantum particles in classical spacetime, then, as you said, these heavy particles should curve space and create mini black holes*. The second has to do with the inconsistency of the idea of quantum particles interacting with classical spacetime, and so we expect that spacetime itself should behave quantum mechanically.

    * No one really knows how to quantize gravity, and so we don't know what gravity does at such short distances. It might not resemble anything like a black hole.
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