On 13 Dec 2012, at 04:39, meekerdb wrote:

On 12/12/2012 4:01 PM, Jason Resch wrote:

On Wed, Dec 12, 2012 at 5:15 PM, meekerdb <meeke...@verizon.net> wrote:
On 12/12/2012 9:25 AM, John Clark wrote:

On Tue, Dec 11, 2012  meekerdb <meeke...@verizon.net> wrote:

On 12/11/2012 9:31 AM, Jason Resch wrote:

>>> Everett's QM is not a theory; it's just an interpretations.

>> Not quite. Deutsch's proposed experiment with reversible computation and an AI yields different results for the CI and MWI, thus they are theories which can be tested and differentiated.
> Except his proposed experiment relies on a hypothetical quantum computer that is conscious.

Yes but Deutsch argues, convincingly I thought, that the reason it's so difficult to test is not the Many World's theory's fault, the reason is that the conventional view says that conscious observers obey different laws of physics, Many Worlds says they do not, so to test who's right we need a mind that uses quantum properties.

In Deutsch's experiment to prove or disprove the existence of many worlds other than this one a conscious quantum computer shoots electrons at a metal plate that has 2 small slits in it. It does this one at a time. The quantum computer has detectors near each slit so it knows which slit the various electrons went through. The quantum mind now signs a document saying that it has observed each and every electron and knows what slit each electron went through. It is very important that the document does not say which slit the electrons went through, it only says that they went through one slit only, and the mind has knowledge of which one. Now the mind uses quantum erasure to completely destroy the memory of what slits the electrons went through. But all other memories and the document remains undamaged.

But why should I think this is possible? I'd like to see the actual mechanism or Hamiltonian that allows this.

And then the electrons continue on their way and hit the photographic plate. Now develop the photographic plate and look at it, if you see interference bands then the many world interpretation is correct.

No, it only means the 'consciousness collapses the wave-function' theory is incorrect. It doesn't follow that MWI is correct.

If observing a definite result doesn't collapse the wave function then what does?

Creating a record of it.

I think the experiment is meant to show collapse does not happen. And if there is no collapse then you have the MWI.

MWI has the same problem as decoherence theory (except it tries to ignore it): How or what chooses the basis in which the reduced density matrix becomes approximately orthogonal and what is the significance of it not being exact. Copenhagen said the choice is made by the experimenter and apparently Deutsch agrees with this because he thinks it's significant that his AI is conscious. Decoherence theory hopes to show it is some objective feature of the experiment, e.g. the Schmidt decomposition and purification has been proposed


Neither has really said how to deal with the inexactness of orthogonality, but once you assume you can ignore the off diagonal terms then QM just predicts probabilities, as Omnes says.

That works FAPP.
But there is no conceptual reason to ignore the off diagonal terms, given that they can play role physically testable. It is instrumentalist.

If you define a world by the transitive closure of interactions, then the linearity of the SWE and the linearity of the tensor product entails the existence of the many worlds. The many worlds is just the literal reading of QM applied to our world including us.

And I think QM itself, the wave, is already a literal reading of arithmetic by itself, ... but I can't convince people who believes in Something or Someone selecting their realities and not the others.



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