Re: Many-Worlds Interpretation

Dan Fabulich (
Mon, 29 Mar 1999 16:57:26 -0500

At 10:00 PM 3/29/99 +0100, you wrote:
> Mike Lorrey wrote:
>> > Perhaps someone can clear something up for me. Does
>> > the MWI solve the observer problem? As far as I can
>> > tell it simply replaces the question, "why do I
>> > observe this state", with, "why do I observe this
>> > world".
>> It answers that question as well, by random chance.
>So it doesn't answer the question.

>From the excellent Many-Worlds FAQ:

Q25 Why am I in this world and not another?

     Why does the universe appear random?
These are really the same questions. Consider, for a moment, this analogy:

Suppose Fred has his brain divided in two and transplanted into two different cloned bodies (this is a gedanken operation! [*]). Let's further suppose that each half-brain regenerates to full functionality and call the resultant individuals Fred-Left and Fred-Right. Fred-Left can ask, why did I end up as Fred-Left? Similarly Fred-Right can ask, why did I end up as Fred-Right? The only answer possible is that there was *no* reason. From Fred's point of view it is a subjectively *random* choice which individual "Fred" ends up as. To the surgeon the whole process is deterministic. To both the Freds it seems random.

Same with many-worlds. There was no reason "why" you ended up in this world, rather than another - you end up in all the quantum worlds. It is a subjectively random choice, an artifact of your brain and consciousness being split, along with the rest of the world, that makes our experiences seem random. The universe is, in effect, performing umpteen split-brain operations on us all the time. The randomness apparent in nature is a consequence of the continual splitting into mutually unobservable worlds.

(See "How do probabilities emerge within many-worlds?" for how the subjective randomness is moderated by the usual probabilistic laws of QM.)

[*] Split brain experiments *were* performed on epileptic patients (severing the corpus callosum, one of the pathways connecting the cerebral hemispheres, moderated epileptic attacks). Complete hemispherical separation was discontinued when testing of the patients revealed the presence of two distinct consciousnesses in the same skull. So this analogy is only partly imaginary.

I like this explanation. You might not agree with MWI, but it does at least answer the questions it has set out to answer, correctly or incorrectly.



               -THEN WHAT DOES-