[ExI] Many Worlds (was: A Simulation Argument)

Stathis Papaioannou stathisp at gmail.com
Tue Jan 8 10:17:11 UTC 2008


On 08/01/2008, Ian Goddard <iamgoddard at yahoo.com> wrote:

>  So you say Occam's 'entities' mean 'assumptions'.
> However, assumptions in a scientific theory typically
> point to physical entities. So I'm not sure you've
> made a meaningful distinction.
>
>  For example, describing the 'simplicity' criterion of
> scientific theories, Copi & Cohen cite Ptolemy's
> theory of celestial orbits versus the Copernican
> theory. The two theories were equally effective
> explanations and predictors of astronomical data. And
> *both* assumed epicycles. But according to Copi &
> Cohen, Ptolemy's model should be rejected because it
> assumed more epicycles. [1] So for each additional
> physical entity (an epicycle) there's an additional
> assumption for that entity. So saying assumptions in a
> theory are distinct from physical entities posited by
> that theory is not a clearly valid claim.

Copernicus' model is geometrically simpler than Ptolemy's, but it
actually implied a much vaster universe. That is because if the Earth
is not at the centre of the universe, the stars should appear to move
as the Earth orbits the Sun. However, the stars did not appear to move
as far as astronomers of Copernicus' time could tell, which meant
either that they were much further from the Earth than the planets
were, or that the geocentric view was correct. It was felt that God
would not be so wasteful as to put so much space between the Earth and
the stars so this was used as an argument against Copernicus' theory.

There are parallels here with quantum theory. The formalism of the MWI
is simpler but it implies that the universe is much vaster than it
appears, which seems wasteful of space and matter if not of divine
labour. Therefore, an additional bit is tacked on to the theory to
explain why the universe we find ourselves in is the one true, solid
and special universe.

>  It's worth noting further that in his 'Rule of
> Reasoning in Philosophy', Issac Newton stated what
> Cushing calls "essentially Ockham's razor" saying:
>
>   "We are to admit no more causes of natural
>   things than such as are both true and sufficient
>   to explain their appearances." [2]
>
> Now, not only do Occam's 'entities' obviously refer to
> physical entities (and as Copi & Cohen utilize their
> given example), but certainly Newton's 'causes' refer
> to countable physical causes out in the world. So here
> again Many Worlds looks to be in violation of the
> simplicity criterion, for it posits the branching off
> of a new world as the cause of an appearance, and
> again and again ad infinitum... ~Ian

Many Worlds is what is left if you remove the assumption of an an
arbitrary "collapse" of the wavefunction precipitated by an
observation. The trimmed down theory then explains all of the
scientific evidence, and as a bonus preserves realism, locality,
determinism and does not bestow on the observer any special status
compared to the rest of the universe.



-- 
Stathis Papaioannou



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