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Does superpostion imply many worlds?

by I2004
Tags: imply, superpostion, worlds
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I2004
#1
Dec25-12, 04:06 PM
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The fact that objects exist in superpostion which means they exist in multiple postions(proven fact), doesnt this automatically imply many worlds?

ignoring collapse interpretations, can there be any single world interpretations of quantum superpostion?
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Simon Bridge
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Dec25-12, 04:41 PM
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The "superposition" in question is of statistics not the object itself.
I2004
#3
Dec25-12, 05:32 PM
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Quote Quote by Simon Bridge View Post
The "superposition" in question is of statistics not the object itself.
but how does superpostion that is statistical show the physical effects as in quantum interference?

Simon Bridge
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Dec25-12, 05:50 PM
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Does superpostion imply many worlds?

The same way any statistics show physical effects.
StevieTNZ
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Dec25-12, 05:51 PM
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I would question that superposition is of statistics. Each individual system is in a superposition.

No - superposition does not imply many-worlds.
Simon Bridge
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Dec25-12, 06:10 PM
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What is the superposition discussed a superposition of if not of the wave-functions - distributions of probability amplitudes which is to say of a statistical construct?

I have been a bit glib though.
For more detail see:
http://vega.org.uk/video/subseries/8

I'm intregued though - how would you, then, support the conclusion that "superposition does not imply many worlds"?
Simon Bridge
#7
Dec25-12, 06:33 PM
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Perhaps we shuld be more careful - there are, after all, three distinct questions here:

1. does superpostion imply many worlds?
Certainly quantum superposition and interference effects are part of the motivation of the Many Worlds interpretation of QM - so the one can be said to imply the other ... however, see 3 below, Many-Worlds is not the only interpretation as any reading of course materials will quickly show.

2. The fact that objects exist in superpostion which means they exist in multiple positions (proven fact), doesnt this automatically imply many worlds?

It is not clear what is meant by "objects ... exist in multiple positions" - does this mean at the same time? Perhaps an example of what is meant would be useful here?

The superposition in question is of position wave-functions - these are distributions of probability amplitudes related to the probability that a particle is in a number of positions rather than the actual position of the particle.

3. ignoring collapse interpretations, can there be any single world interpretations of quantum superpostion?
Well ... if we ignore alternative interpretations, we are left with Many Worlds - yes. I don't think this is what was intended though.

I think there is a basic misunderstanding here which StevieTNZ has touch upon: the math is not the object. When we say "a particle is in state Y" we mean that the things we are interested in about it are described by state-vector Y.

Any state vector can be described as a superposition of other vectors.
We choose the particular representation to suit the math we want to do - we could choose a representation in which the particle is in a pure state rather than a superposition. In which case, the same argument implies a "single world" event.
StevieTNZ
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Dec25-12, 10:01 PM
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We can also utilize Many-Minds instead of Many-Worlds.

By superposition, I interpret that to be potential ("classical) states rather than an actual state existing in all three physical configurations (e.g. three different positions) at one time ("classically").
haael
#9
Dec26-12, 02:57 AM
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Quote Quote by I2004 View Post
The fact that objects exist in superpostion which means they exist in multiple postions(proven fact), doesnt this automatically imply many worlds?
If the quantum mechanics unchanged applies to the macroscopic world, then yes, many worlds is the only possible interpretation.

Quote Quote by I2004 View Post
ignoring collapse interpretations, can there be any single world interpretations of quantum superpostion?
Yes, provided that something changes in the way from the microscopic to the macroscopic world. It is possible that objects of certain size (i.e. exceeding Planck mass) cannot exist in superposition. Or at least the usual linear equations of QM break and some nonlinearity is introduced.

Many worlds interpretation may be summarized in a simple statement: linear equations of quantum mechanics rule the macroscopic world.


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