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Metrics, +++- vs +++-

  1. Apr 12, 2011 #1
    Metrics, +++- vs +++--

    There are reasons why our space is 3D. In 2D all systems are bound, in 4D they are unstable.

    What 'reasons' are for having 1D time vs 2D time? I don't want to go deep into the AP stuff; just may some constraints one might know like 'Maxwell equation wont be consistent' etc.
  2. jcsd
  3. Apr 13, 2011 #2


    Staff: Mentor

    Re: Metrics, +++- vs +++--

    With 2 timelike dimensions you could have closed timelike curves even in flat spacetime. I don't think we would have causality in such a universe.
  4. Apr 13, 2011 #3
    Re: Metrics, +++- vs +++--

    hm, interesting, you're right.
    Yes, if there are 2 "times", t and u, then null path can be defined as
    s^2 = t^2 where u=0 for example,
    which makes lightspeed 'instantaneous' in some directions of time.
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