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I If the universe is a simulation, on what does it run?

  1. Aug 23, 2015 #1
    If digital physics is true and physical reality consists of computations, then what could possibly be the computational platform, i.e. where could the computations be run on? What are possible answers explored in digital physics?
    Last edited: Aug 23, 2015
  2. jcsd
  3. Aug 23, 2015 #2
    Let's wait for God to answer this one.
  4. Aug 23, 2015 #3
    :smile:... No, but seriously... What could the platform possibly be? In the literature so far I have encountered up til now only 2 options: (1) That our universe is a simulation run on a physical computer designed by some advanced civilization (the Matrix scenario, explored by Nick Bostrom). (2) Mathematical platonism: all numbers and all computable functions simply exist in 'platonic heaven' and among those algorithms are those that instantiate our universe (Frank Tipler, Tegmark, Bruno Marchal). I wonder if there are other physicists who have different ideas about this issue.

    Option (1) is of course bogus, also because it is not consistent with a thoroughgoing digital physics. If we want to reduce physical nature to computation then it won't do to postulate a prior physical computer on which the computations are run... This type of answer is in danger of a regress: the universe is a simulation inside a simulation etc. ad inf.

    Option (2) is interesting but of course very speculative. It stands or falls with the acceptability of mathematical platonism.
  5. Aug 23, 2015 #4


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    Gold Member

    If unicorns existed, how long would their horns be?
  6. Aug 23, 2015 #5
    If all of physics is a simulation then the simulating platform must itself be a simulation and so on ad infinitum ...
    Unless the chain eventually stops with something that is 'the real thing' and is not a simulation.
    In that case though there is no reasonable argument at all to make as for why things are simulations in the first place.
  7. Aug 23, 2015 #6


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    That question cannot, even in principle, be answered by experiment or the methods of empirical science. Thus, it has the same status as Phind's rhetorical question (which was, I expect, the point he making by asking it) and is out-of-scope for Physics Forums.

    This thread is closed.
  8. Aug 23, 2015 #7


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    Staff: Mentor

    In an offline conversation, someone suggested that "dozens of respectable physicists are discussing digital physics" and therefore that this thread should not be closed.

    The PhysicsForums rules discourage philosophical speculation, even when it is supported by respectable physicists. Physicists have as much right to think and write about philosophical questions as anyone else, but these writings remain out of scope for PF. Furthermore, there is a very wide gap between discussing the methods of digital physics (which will stand or fall based on whether it produces effective tools for describing the universe) and the status of mathematical Platoism.

    The thread will remain closed.
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