On Monday, October 15, 2018 at 9:40:39 PM UTC+11, [email protected] wrote: > > > > On Sunday, October 14, 2018 at 5:08:42 PM UTC, smitra wrote: >> >> On 14-10-2018 15:24, [email protected] wrote: >> > In a two state system, such as a qubit, what forces the interpretation >> > that the system is in both states simultaneously before measurement, >> > versus the interpretation that we just don't what state it's in before >> > measurement? Is the latter interpretation equivalent to Einstein >> > Realism? And if so, is this the interpretation allegedly falsified by >> > Bell experiments? AG >> >> It is indeed inconsistent with QM itself as Bell has shown. Experiments >> have later demonstrated that the Bell inequalities are violated in >> precisely the way predicted by QM. This then rules out local hidden >> variables, therefore the information about the outcome of a measurement >> is not already present locally in the environment. >> >> Saibal >> > > What puzzles me is this; why would the Founders assume that a system in a > superposition is in all component states simultaneously -- contradicting > the intuitive appeal of Einstein realism -- when that assumption is not > used in calculating probabilities (since the component states are > orthogonal)? AG >
I think because of interference. Consider the paradigmatic double slit, with the single electron going through it. It sure looks like the electron was in two place at once, doesn't it? I'm not sure what you mean by "that assumption is not used in calculating probabilities". If you take a sum-over-histories approach it's explicitly assumed the electron went via all possible paths. I don't see what the orthogonality of the basis vectors (and hence component states) has to do with the question of interpretation of superposition. Clearly the system will be measured in only one state, and this is what the orthogonal vectors represent. However the quantum state itself typically spans more than one dimension of the vector space - that's what a superposition is. However I think when physicists say that the superposition is in all states simultaneously, it's only in a manner of speaking - a way of conveying the mathematical situation in natural language that is inherently classical. Reading Born's exchange of letters with Einstein (I'm proud to say Born was my great grandfather), it's clear that Born had a conception of QM that was still very realistic in the Einstein sense. Though they disagreed significantly and somewhat heatedly, Born still seems to have regarded QM probabilities as classical probabilities in disguise. I don't think he would ever have endorsed the notion that a particle is truly in all of the states of the superposition simultaneously. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
