Re: Many-worlds (was Re: [sl4] Re: Uploads coming first would be good, right?)

From: Stathis Papaioannou (
Date: Fri Mar 06 2009 - 18:23:15 MST

2009/3/7 Matt Mahoney <>:

> It is impossible for an observer inside the universe to know its state.
>> To give another example, a computer program with an
>> observer that branches into two processes, one where the observer sees
>> heads and the other where he sees tails, will be completely
>> deterministic viewed from outside, but it will seem to the internal
>> observer that he has a 1/2 chance of seeing heads or tails, even if he
>> has full access to the source code and the data.
> The program will estimate a probability that depends on how it was programmed. It cannot have full access to the source code and data by the above theorem.

The irreducible randomness of the first person perspective does not
come from an inability of an observer to fully know the universe's
state. It is easy to imagine special cases where the observer knows
everything relevant about the experiment: at 10 AM I will be
duplicated, one of the copies will see heads and the other copy will
see tails. In the case of a classical coin toss in a non-branching
universe, assigning a probability of 1/2 to heads is due to partial
ignorance: I know how a series of past coin tosses have turned out,
but I don't know how this particular one will turn out, for if I did I
would assign heads a probability of either 1 or 0. But in the former
example although I know exactly what is going to happen, I don't know
what I'm going to experience.

Stathis Papaioannou

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