Hi Bruno and Friends,

    I have some comments and questions interleaved below.
  ----- Original Message ----- 
  From: Bruno Marchal 
  To: everything-l...@googlegroups.com 
  Sent: Friday, December 19, 2008 2:56 PM
  Subject: Re: Time

  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).
  I will just add general remarks to Brent's reply.

  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.


    Is this conclusion following ideas like those of Julian Barbour? Lee Smolin 
in several papers thas shown quite convinsingly that Barbour's theory has some 
serious problems. For instance see:  


    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 


    How are we sure that GR needs to be "quantized" at all? We have, with QM, a 
very good theory covering all notions of "interactions" in terms of their 
energy, charge, spin, etc; why is it necessary to "quantize" geometry? What is 
geometry is a derivative quantity and not a primitive? After all, In Bruno's 
model our observed universe is derived from NUMBERS...

    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.


    Here is where I have a serious difficulty with Bruno's idea (all the while 
I must admit that I am in awe of its elegance) it is the fact that all notions 
of "observable" quantities in QM are coded in terms of complex numbers ( 
http://en.wikipedia.org/wiki/Complex_number ) as "amplitutes" 
(http://en.wikipedia.org/wiki/Amplitude)- which have no notion of a unique 
successor relation - until after a particular notion of a physical world in 
introduced to allow for the operation of "reduction of the wavefunction" or 
what ever equivalent procedure implements the Born's rule: 

    Thus QM tells us that the Universe is Complex valued and thus we have a 
severe problem in that there is no unique  and a priori ordering of events from 
which to derive a first person notion of time or a "flow of events".
              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.


    Does not this property of being " isomorphic to the lattice of open sets in 
a complex topological space and/or Hilbert Space" make my point that there does 
not exist a unique ordering?! A simple and visualizable proof of this is seen 
in that a 2 dimensional Euclidian Plane does not have a unique line or subset 
that would seperate one portion of the Plane from another; or in English: there 
does not exist a unique way to cut a piece of paper into two pieces.

     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.


    But substituting an Asymetry between events for 1st person time does 
nothing to further our questions. Unless there is a means to derive a notion of 
a measure or an ordering from primitive arithmatic (that is not that of Natural 
numbers!) we are still where we started on this excursion. :(

    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)


    Given all of that, does there not still remain the need for a measure with 
which to "order" the histories? It almost seems that the nature of the 
isomorphism elaborated upon above leadws dirrectly to a "NoGo" theorem here... 
Since no unique ordering can exist on a complex

    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.


    Does this "self-diffraction" not relie in some way on some from of measure? 
If the measure is arbitrary and not derived, all we have, AFAIK, is an example 
of a random walk... 
          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 




    I will continue to read the posts. ;)

Kindest regards,

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