Re: being inside a universe

From: Bruno Marchal <>
Date: Mon, 8 Jul 2002 17:22:11 +0200

At 9:33 -0700 5/07/2002, Wei Dai wrote:
>On Thu, Jul 04, 2002 at 04:07:42PM +0200, Bruno Marchal wrote:
>> [Hal Finney wrote:]
>> >In general, universes are created by more than one computer
>> >program. The measure of a universe is proportional to the number of
>> >computer programs which create it.
>> Glad you say so. This is *not* true for Schmidhuber and those who
>> keep an absolute interpretation of the SSA (cf Bostrom Self-Sampling
>> Assumption). Big and slow programs are discrimate away by Juergen,
>> I argued this cannot be done a priori.
>What Hal said is compatible with discriminating against big (but not
>against slow) programs, if you consider infinite strings as programs,
>parts of which may never be read by the computer, and interpret "the
>number of computer programs which create a universe" as the proportion of
>infinite strings which output the universe, and the size of a program as
>the number of bits of the infinite string which is read.

Programs and machines are generally considered as finite. I could
interpret an (perhaps arbitrary) infinite string as an oracle, but then
you should be more precise of what it means by "create (output) a universe" ...

> > I don't think we can look into an "output" in that way. For the same
>> reason we cannot look at your sleeping brain for seeing if you are
>> dreaming about a banana. This is again linked to the 1/3 distinction.
>You're right that we can't do this very well today. We can't look at a
>brain from a third person perspective and determine exactly what it's
>experiencing, but we should be able to do it in the future with better
>technology. Even today we can get some probabilistic information about
>what the person might be experiencing. We can tell whether someone is
>awake or asleep, whether he is experiencing anger or calm, etc. If we
>allow looking at the environment around the brain and making probabilistic
>inferences, we can do even better. For example if we see a person facing
>an apple with his eyes open, then we can infer that he is probably seeing
>an apple. Similarly if I see an apple, I can infer that I'm probably in a
>universe where I'm facing an apple with my eyes open.

You are right.I am sure we will have machine capable of making the image
of a banana appearing when you are thinking into it. My use of this
analogy was incorrect, strictly speaking. What I say is that the experience
of the banana cannot be attached to the "brain behavior alone", unless you
mean by brain the entire set of computational (quantum if you want) stories
going through that comp state. This was shown by the uda (but see below):
You can attribute a mind to a machine, but it is not possible to attribute a
singular machine to your own mind, except locally and relatively.

>> I would say the flaws are both in the too much static view of a computer
>> output programs, where I think "universe" are first person emergent on the
>> running of all computations.
>What is the motivation for defining "universe" this way?

I give more than a motivation, I suggest (at least) an obligation!
First here, I could ask you how you define a universe. That's not obvious
at all. But the uda shows that my next experience is given by some average
on all possible experience in my computational neighborhoods. So that with
comp the universe, if any thing like that exists, must emerge from that
average. The difficult things is how to define that average, and eventually
this leads me to the interview of the UM.

>The third person concept of a universe as the running of a computer
>program (I agree that the running of it is a more useful concept than the
>output considered statically) is useful in simplifying decision making.
>It allows you to consider the consequences of an action in each universe
>independently, knowing that they do not interact with each other.

They do not interact, but they do interfere, by changing the relative
possible probabilities of occurence of that or this story. Quite similar
with what happens in Quantum Mechanics, where the many worlds interfere
without interacting.

>But how do you make use of your first person concept of universe? (I'm not
>sure what the concept is exactly yet, but perhaps your answer to this
>question will help.)

Remember that the UD, or the Schroedinger Wave Equation (SWE), multiplies
you "all the time". The difference between first and third person point of view
is the difference between an outside description, in which you can labelise
the multiplied observers, and the personal notes-book/memory of each observer,
who, if the multiplication has been done at the right level (existing by comp),
will not *feel* the existence of their counterparts. I use 1-person point
of view where Everett talks about subjective memory, and 3-person point of view
where Everett uses objective.

If I am duplicate, I will experience first person indeterminacy (ignorance
of what I will write in my personal diary), although
everything is determined from a third person point of view. (Comp
Do you agree with this?

Received on Mon Jul 08 2002 - 08:21:10 PDT

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