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Is it possible to have an xy plane with z as time?

  1. Mar 3, 2014 #1
    Shortly after the Big Bang was there an extremely brief period of time when the universe consisted of an xy plane with z as time, the third dimension? In other words did a three dimensional universe predate a four dimensional universe?
  2. jcsd
  3. Mar 3, 2014 #2


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    Do you have any reference for this idea?

    There is a concept (especially pursued by Professor Steven Carlip) that at very short scales (Planck length), the number of dimensions decreases (spontaneous dimension reduction). However, I have no idea of this is what you are referring to. Also, z is just a letter of the alphabet. If z functions as time, you might as well call it t (or Bob for that matter; it doesn't matter what you call it).
  4. Mar 4, 2014 #3
    No--I do not have a reference for that idea. Yes---that is what I meant about the third dimension being time. I was not familiar with the work of Professor Steven Carlip and can only speculate that these dimensions may even be shorter than the Planck length.
  5. Mar 4, 2014 #4


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    I know that Carlip has worked on 2+1-dimensional gravity as a simple model for both classical and quantum gravity, but I can't find any mention that he thinks it has any connection to reality, even at the Planck scale.
  6. Mar 4, 2014 #5


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    I am referring to a more recent line of his work. See:

    [edit: more on this line of research]
    Last edited: Mar 4, 2014
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