Nick Prince wrote:
Hi Brent

Perhaps Bruno could give some clarification  here. Just prior to his
conclusion on the sane paper I quoted from was this:

"So if we keep comp at this stage, we are forced to relate the inner
experience only to
the type of computation involved. The reason is that only those types
are univocally related to
all their possible counterfactuals. This entails that, from a first
person point of view, not only
the physical cannot be distinguished from the virtual, but the virtual
can no more be
distinguished from the arithmetical. Now DU is emulated
platonistically by the verifiable
propositions of arithmetic. They are equivalent to sentences of the
form ‘‘it exists n such that
P(n)’’ with P(n) decidable. Their truth entails their provability, and
they are known under the
name of Sigma1 sentence.
If comp is correct, the appearance of physics must be recovered from
some point of
views emerging from those propositions. 

Why only the atomic sentences?  Why not all true sentences?  How is "appearance" recovered?

Indeed, taking into account
the seven steps once
more, we arrive at the conclusion that the physical atomic (in the
Boolean logician sense)
invariant proposition must be given by a probability measure on those
But what gives the probability measure?  Is it just the relative frequency of occurrence of the atomic sentences in the UD output up to a given step?


physical certainty must be true in all maximal extensions, true in at
least one maximal extension (we will see later why the second
condition does not follow from the first) and
accessible by the UD, that is arithmetically verifiable. Figure 8
illustrates our main
conclusion, where the number 1 is put for the so called Sigma1
sentences of arithmetic."

It sounds as if Bruno thinks that the computations of the UD invoke
our inner experiences and also our understanding of  physics.  Both
come from arithmetical platonicism ( because thats what the UD is all
about).  So the pictures in the "film" are stiched together by the
arithmetical (computation necessity) rather than the laws of of
physics... Hmm not what I thought and said earlier!!

So according to Bruno the laws of physics come from something
intrinsic in the computation?  Not quite sure how.  I just can't
figure out any more at the moment and hope Bruno will give me a hint

Enjoying the dialogue!


On Jan 5, 10:44 pm, Brent Meeker <> wrote:
Nick Prince wrote:
OOps sorry I sent an empty post by accident.
I agree with you here.  But I am new to this field so I am uncertain
about so many things.  However, I don't understand why it is that  a
UD would know how to generate these law like sequences of states. It
may well generate all possible programs that generate all possible
universes (with different values for the physical constants say -
maybe even different laws) but I wonder why our conciousness defines
itself by "selecting" only those "consistent" extension among all the
states available that obey a certain set of  laws of physics.
I thought that a TOE should explain the laws of physics and Bruno
states in his SANE paper
" Conclusion: Physics is given by a measure on the consistent
computational histories, or
maximal consistent extensions as seen from some first person point of
But consistent in what sense?  We can't say "consistent with the laws of
physics" because that's what we're trying to explain.

Laws of physics,
in particular, should be inferable from the true verifiable atomic
sentences . Those are the
verifiable arithmetical sentences.
I understand true arithmetical sentences, but I'm not sure what
'verifiable' means?  Does it mean computable, or provable?  What's an
atomic sentence?  Is it just a finite statement, like "17 is prime"; so
it excludes infinite statements like Goldbach's conjecture?


They should be true everywhere (=
in all comp histories),
true somewhere (= true in at least one comp history), and inferred
from the DU-accessible
atomic states".
It feels a bit lie a chicken and egg situation - do we pick out the
laws or do they pick us?. But I am still working my way through this
and  and loads of other stuff, so I don't understand it yet.
On Jan 5, 6:59 pm, Brent Meeker <> wrote:
Nick Prince wrote:
Is this because you think of your stream of consciousness as somehow
like a reel of film?  All the individual pictures could be cut from
the reel and laid out any which way but the implicit order is always
there.  I can understand this because all the spatio temporal
relationships for the actors in the film remain "normal" i.e obey the
laws of physics.  
But there's the rub.  Why the laws of physics?  That's what somehow
needs to be explained.  Is there something about the UD that necessarily
generates law like sequences of states with high probability?  Doesn't
it generate just those laws we seem to find - that would be a great
discovery.  Or does it generate all possible non-self-contradictory
multiverses - in which case nothing has been explained.
Deutsch argues similarly in the Fabric of reality.
In my work I often come across the idea of a foliation of
hypersurfaces which is really a set of 3D pictures "stuck together and
stacked in the direction of the time coordinate of the world at a
given instant of time.  
But that's starting with the physics given, so the hypersurfaces and
their relation is already defined.
In MW interpretation though I guess that the
stacking is less certain as in the block universe idea but that's
another issue.  Is this analogy similar to how you feel  the "obvious"
experience of time being normal?
Nick- Hide quoted text -
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