On Mon, Dec 10, 2012 at 10:30 AM, meekerdb <meeke...@verizon.net> 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. If the Everett approach is correct then the atom will be in the same state that it was in before the measurement, it will still have a 'left' spin. --- http://www.thestargarden.co.uk/EvidenceOfParallelWorlds.html Jason -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to firstname.lastname@example.org. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.