# Re: Time

```Bruno,

>From what assumptions could a probability ultimately be derived? It
seems that a coherent theory of the probability of future events is
needed (otherwise the passing of time could be white noise), but I do
not see where such probabilities could come out of more basic
assumptions. To reason about the future, we assume that we are in a
randomly chosen computation-- but then we are already using some
probability distribution.```
```
Evolution is at the root of our ability to predict probabilistically.
We use one probability distribution over another because it helps us
survive. However, this is not good enough of an answer in the
multiverse: every possible form survives anyway. To keep talking about
evolution, we would need to talk about which forms are more common in
the multiverse. But to count how common forms are, we would need some
measure over the multiverse, which could give us a probability
distribution in the first place. So every possible argument seems
circular.

So, I don't need all the details of your derivation of a probability
(though I'm interested); but what assumptions can you get a
probability distribution from?

-Abram

On Fri, Dec 19, 2008 at 2:56 PM, Bruno Marchal <marc...@ulb.ac.be> wrote:
> Hi Abram,
>
> I agree mostly with Brent's reply. Other precision should appear in my
> explanation of the UDA to Kim, and in my answer to Ronald (Sunday).
>
>
> Le 19-déc.-08, à 00:18, Abram Demski a écrit :
>
>
> [Sorry if this is a duplicate, I think that I did not send correctly
>
> the first time.]
>
> Bruno, everyone,
>
> I've decided that it will be more productive/entertaining to post my
>
> various concerns as a new topic.
>
> What is time?
>
> Third person sharable time could be an illusion. It seems to me that QM +
> General Relativity could lead to the idea that there is no real "physical
> time". With MEC this is a direct consequence of the UDA.
> First person time, or subjective, akin to Bergson notion of "duration" can
> be explained in the AUDA. It appears that the formal notion of first person
> leads naturally toward a temporal logic. Like in Plotinus, the "soul" is the
> creator of time.
>
>
>
>
> I'm going to ask a bunch of questions; for the sake of brevity, I'm
>
> going to skip my arguments (which would mostly be reasons why
>
> particular answers don't work). I'll argue once someone replies.
>
> If all possible universes exist, does that mean every possible moment,
>
> or every possible timeline of moments? If "moments" is the answer,
>
> then how are the moments connected? How would it matter, since the
>
> moments already are what they are? If "timeline" is the answer, then
>
> there is a similar question of how it matters.
>
>
> What do you mean by "how it matters"? It is a bit like free will. It exists
> because from our points of view we cannot know the "end of the novel".
> That ignorance, and thus free will is preserved by the mechanist hypothesis.
> It is even made intrinsical.
>
>
>
> If there is a physical universe, then is there some sort of basic
>
> physical connection behind time?
>
> Open and difficult problem for the physics you can extract from comp. Of
> course, if there is a primary physical universe, we have to resolve the
> problem of marrying QM and GR before being able to answer your question.
> Very difficult question.
>
>
>
>
> If the universe is mathematical in nature, then what is the
>
> mathematical connection between moments? What sort of mathematical
>
> connection counts as time?
>
>
>
> I would say that it is logic-mathematical connections. With MEC those
> relations eventually originates with the natural number successor relation.
> I will say a bit more sunday in my answer to Ronaheld. The problem is that
> it is hard not being a bit technical here. You have to understand the
> mathematical concept of computation, and then to understand that those
> computations exists in arithmetic, and indeed are accessible through proof
> in a very tiny part of arithmetic: the theorems of Robinson Arithmetic (RA).
> RA is Peano Arithmetic *without* the induction axioms.
> PA is the lobian machine. And RA generated all the histories which notably
> contain all the Lobian machines. RA simulates PA like I can simulate
> Einstein's brain, or a Chinese brain. This is a subtle point where people do
> sometimes the Error of Searle with his Chinese Room.
>
>
>
>
> If (as was recently suggested, in connection with relativity) time
>
> cannot really be divided into individual moments, then what is it?
>
>
> It is an ordering on machine knowledge states, and/or observation states.
>  It is a very complex ordered structure (should be isomorphic to the lattice
> of open sets in a complex topological space and/or Hilbert Space). I
> approach the math of those spaces with the modal logic of self-reference and
> their intensional variants.
>
>
>
> Why do we experience time passing?
>
>
>
> Each of our knowledge state are relative state generated by "a most probable
> computation" (generated by the UD, or living in arithmetic). Mainly by
> ignorance, we feel our knowledge being divided into a sort of
> past-certainty, and sort of future-uncertainty. Those things can be
> described by modal logic. I argue all those modal logic arise from
> self-reference in arithmetic.
>
>
>
>
> Is it legitimate to think as if the next moment we experience will be
>
> chosen randomly in some sense?
>
> Yes. I believe everyone in this list agree with this, but differ on the
> distribution law, the relative or absolute nature of the probabilities, and
> about the nature of the events on which the probability bears on.
> In the case of comp, I argue (through UDA+AUDA) that our next experience is
> chosen randomly on the set of all computations going through our actual
> state which have been generated by the UD, or are "living" in that tiny
> arithmetic.
> There are 2^aleph_0 histories. The measure should be non constructive (thus
> physics cannot be entirely described by a program or machine)
>
>
> Does probability or randomness have a
>
> role to play in the flow of time?
>
>
> I would say yes, given that once a universal machine observes itself it
> separates a growing "past" from a growing "future".
> There is a sort of self-diffraction: the better a machine observes itself,
> the bigger is the set of possible futures (consistent continuations of
> computations) she gets.
>
>
> In connection with UDA: what is the meaning of a first-person
>
> probability due to uncertainty of the future?
>
> I will explain this soon to Kim. I suggest you ask in the case this remains
> unclear, or if you have objection. It is not possible to explain this
> shortly.
>
> Is there any sense in
>
> which such estimates can be more or less accurate if all possible next
>
> moments do in fact occur?
>
>
> All what we have to do consists in finding discrepancies between the theory
> and the observations. I bet QM is correct, so I tend to bet that the comp
> estimation of the possible moments will give the same estimation than QM.
>  This would explain where QM comes from. This remains to be seen of course,
> but formally, preliminary modest results are going in that direction. Bits
> and Qubits comes from each other.
> Hope this short answer to difficult questions can help. I will say more to
> Ronald Sunday, and I invite you to follow the KIM thread where I explain
> UDA. And perhaps then I can explain AUDA with the amount of technical
> details demanded.
>
> Bruno
> http://iridia.ulb.ac.be/~marchal/
>
> >
>

--
Abram Demski

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