On 12/11/2012 9:53 AM, Jason Resch wrote:
On Tue, Dec 11, 2012 at 12:48 AM, meekerdb <[email protected] <mailto:[email protected]>> wrote:On 12/10/2012 10:01 PM, Jason Resch wrote:On Mon, Dec 10, 2012 at 1:35 PM, meekerdb <[email protected] <mailto:[email protected]>> wrote: On 12/10/2012 10:16 AM, Jason Resch wrote:On Mon, Dec 10, 2012 at 10:30 AM, meekerdb <[email protected] <mailto:[email protected]>> wrote: On 12/10/2012 2:56 AM, Bruno Marchal wrote:But why isn't "It's a probabilistic world and it obeys the Born rule." a good explanation. I'm all for finding a better explanation, i.e. a deterministic one. But simply postulating an ensemble of worlds to make the probabilities "deterministic" in arbitrary way doesn't strike me as any improvement.It is, as it explains interference, without adding something not well defined (apparatus, observer) not obeying QM (like with the collapse needed to get one physical reality).That sounds like prejudice against probabilistic theories. The interference is inherent in the complex Hilbert space states. The interference happens in one world. As Omnes says, you don't need 'collapse' you just need to accept that you have calculated probabilities. That's what probability means - some state is actualized and others aren't. How does Omnes explain the EPR experiment without collapse? It seems you need to give up not only determinism, but also locality. Also, what do you think Omnes would predict as the outcome for Deutsch's proposed experiment: In Deutsch's thought experiment, an atom, which has a determinate spin state in one axis, 'left' for example, is passed through a Stern-Gerlach apparatus which has the possibility of measuring it in another axis, as either spin 'up' or spin 'down' in this case. This means that the atom is then in a superposition of 'up' and 'down' states from the perspective of an observer who has not yet become entangled with it. This superposition travels to the AI's artificial 'sense organ'. Here it is provided with two options, it may be detected as either spin 'up' or spin 'down'. The AI's conscious mind then records the result. The collapse approach predicts that this will cause the atom to collapse into one determinate state, with either a determinate 'up' or 'down' (but not 'left' or 'right') spin. The Everett approach predicts that the mind will branch into two, one mind will record up and one down (but neither will record 'left' or 'right'). The whole process is then reversed so that the atom emerges from the entrance to the Stern-Gerlach apparatus and the mind forgets which result it recorded. This process does not erase any of the AI's other memories however, including the memory that they did record the atom to be in a definite state. If a 'left-right' detector was placed at the entrance of the Stern-Gerlach apparatus then the collapse approach predicts that it will be detected as being in either a 'left' or 'right' state with equal probability.I think it is wrong in saying that the erasure of which-way information (which I think is actually impossible for a consciousness, artificial or otherwise) will leave the atom in an up/down state. Isn't that exactly what the quantum erasure experiment shows?Quantum erasure requires that the which-way information be eliminated from the world. Once an AI consciousness gets the result I think that implies entanglement with the world and after that the result can't be quantum erased. What theory of consciousness are you operating under? CTM or something else? I know Deutsch supposes a quantum computer AI can 'know' there was which-way information even though the which-way information was quantum erased. But I find that doubtful. And even if it's true, the 'reversal' may bring the atom back to 'left'. That is the proposed result that would prove MWI.
It doesn't prove MWI, it disproves "consciousness causes collapse"; which is a theory no one holds anymore.
If the "left" state is restored always then the universe never collapsed, it split a difference was observed, and a record of observing that difference was stored, then all information pertaining to the result is erased such that the two universes recombine (the split was undone, even though it should have collapsed because the difference was observed).
Only in a Wignerian theory of collapse where 'observed' means by some magic (AI) consciousness.
Why do you think it is impossible for a conscious process learn the result and then have that result erased as in the quantum eraser experiment?Because I think consciousness must be quasi-classical. Consciousness needs stable memory and it needs to interact with its environment - together I think that implies it must be essentially classical as a computer.In this case it has stable memory, and is able to interact with its environment, but then all traces of its memory of the which-way result are erased.
It's the 'all traces' which I think make this impossible. But I'm open to seeing the description of the quantum state evolution and how the erasure is accomplished. Has Deutsch published one?
We operate with unstable memories and forget things, and yet are still conscious. That's one of my reservations about Bruno's oft repeated assertion that he has proven that matter doesn't exist.He says matter exists, but that it is not primitive. It can be explained in terms of something more fundamental.When pressed he allows that it may exist, but only derivatively within the computations of the UD. But it seems to me likely that it, or something very like it, must exist (derivatively of not) in order that consciousness exist; that 'matter' is necessary for consciousness of a human kind to exist. I think it's appearance is probable for entities such as we who evolved.
I'm saying something more definite. That consciousness requires matter (i.e. a quasi-classical world). This would entail that a pure quantum computer (all proposed quantum computers have classical outputs - for obvious reasons) cannot be conscious.
You keep asking me about 'collapse', but Copenhagen's physical collapse is not the same as Omnes epistemic collapse. I am sorry. I don't feel I have a good understanding of what the distinction is.Omnes looks at it as a mathematical operation used in predicting experimental results. That means the 'collapse' is just a change in description, not a physical process.If it's not a physical process and only a description of appearances, it sounds more like MWI.
Is MWI just an abstract ensemble invented to give a picture of probability as sampling? Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
