Relativistic time exists only for embedded observers (observed rate of change in an observer's environment, relative to its own rate of change). I don't know how to make global continuous time work without making the universe hypercomputational.
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I intended to refer to the time of the computation, not of the observer (the latter is much later in the understanding of the model). You mentioned a succession of states, step by step, that time I was asking about. Step by step -> discrete. But finite or infinite?
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I do not know how to get evidence for that. If a universe is deterministic and has finite size, it becomes periodic if you let it run for long enough, and an embedded observer cannot find out when it started, if it had a starting point.
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Ok, I‘m fine with that kind of circular time (up to isomorphism).
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A periodic universe might offer some evidence for its periodicity though!
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Might. Btw., do you see arguments for reversible computation? (The less it is reversible, the hidden its past is. Hm. Thats actually a kind of reversibility from inside. Better I take that back, and think about it before :-) )
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A periodic universe is reversible. Our universe appears to be reversible: You cannot delete information. Entropy reflects the increasing cost of observers to keep track of increasing history.( Note that reversible does not have to mean symmetric.)
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I see. I didn‘t think about this implication of periodicity. Doesn‘t really sound like what I mean with reversability, but that‘s not your problem :-)
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The definition of reversible computation is that every state can have only exactly one possible preceding state. This way, you can construct an inverse rule, and derive the past from the present (if you have full information).
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Yes, and in case of periodicity this is given, even (and this was what I learned from your tweet) if this reversibility is not a property of the step-function alone, but of the step-function and the (subset of) states that are possible in this universe.
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You can also have a deterministic or indeterministic infinite memory universe that is reversible and not periodic, and an indeterministic finite memory universe that is not periodic.
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