# [extropy-chat] Is Many Worlds testable?

John K Clark jonkc at att.net
Mon Jan 1 21:52:48 UTC 2007

```"scerir" <scerir at libero.it>

> I agree that MWI has nothing to do with consciousness
> and 'human' observation

OK.

> It seems difficult to believe that MWI has nothing
> to do with measurements. No measurements no probabilities.

It may be hard to believe but it's every bit as consistent as Copenhagen. In
Copenhagen before a measurement is made the cat is both alive and dead; in
Many Worlds the cat is either alive or dead. True, we will need a
measurement to find out which state the cat is in, but our observation will
not effect the cat.

> My question was: what about the MWI now?
> Can it explain what happens, avoiding
> the role of the consciousness/knowledge
> of the observer?

In your thought experiment in one universe a particle hits a small target
and is absorbed, in another it does not hit the target, so that is when they
split because the universes are no longer identical; one has a particle
still moving in it and one does not. If an observer does not see it hit the
small target he knows he is not living in one of the universes where it did,
if a coconut doesn't hit me on the head I know I'm not living in a universe
where it did. So What? When a conscious observer can figure out which
universe he is living in depends on how far he is from the target, if he is
looking at it, if he is thinking about it, how fast he can think, and
various other irrelevant factors.  Universes split when they become
different, they merge when they become the same, and measurement doesn't
enter into it.

Do the two-slit experiment, but instead of using film to stop the photon
after it pass the slits, let it head out into infinite space. If Many
Worlds is correct the entire universe splits into 2 when the photon hit's
the 2 slits, and never recombines. There is nothing special about you the
observer, you split just like everything else, you know that the photon went
through one and only one slit, but of course you have no way of knowing
which one.

Now let's do the more usual two-split experiment and put the film back in.
The universe splits just as it did before when it passed the two slits, but
when the photon hits the film and it no longer exists in either universe
then the 2 are identical and fuse back together again. Looking back we find
evidence that the photon (or electron) went through both slits and this
causes an interference pattern. Again there is nothing special about an
observer in this, the same thing would happen if nobody looked at the film,
or even if you used a brick wall instead of film, because the important
thing is not that the photon makes a record (whatever that is) but simply
that it is destroyed.  Mind has nothing to do with any of this so I don't
need to explain it, or measurement, or record, or observation, or
consciousness. That is a very very big advantage! Yes I have a truly
marvelous proof of all these propositions, but unfortunately the margin
of this post is too narrow to contain it.

John K Clark      jonkc at att.net

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