Timeline for Entanglement and simultaneity
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
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| May 28 at 6:36 | comment | added | Martin | It's not useless, because it allows for very good predictions. That is all we care about in a physics, everything else is philosophy. There have been many attempts to make a better theory where the states "represent reality" (most notably Bohm's theory), but none of them can come close to what regular quantum mechanics can do. That doesn't mean there aren't a lot of physicists who care about the ontological underpinnings of quantum mechanics - there are - but those do NOT determine the usefulness of a theory. | |
| May 26 at 18:05 | comment | added | Juan Perez | But if the state is just "our knowledge" and changes on state don't imply physical changes, then doesn't that mean quantum mechanics is useless since it doesn't represent reality? If you say QM is a physical model, then the state needs to represent reality. And changing the state of A by measuring B needs to imply a real physical change. Otherwise QM is just useless... | |
| Dec 23, 2014 at 23:46 | comment | added | Martin | If the state is ontic, we have to deal with the "collapse" somehow. As far as I know, a completely Lorenz-invariant ontic theory is unknown, hence the question is not settled yet. I might be mistaken on that point, though, I'm not extremely well versed in quantum foundations. | |
| Dec 23, 2014 at 23:44 | comment | added | Martin | @neuronet: The problem you are having boils down to this: Is the wave-function epistemic or ontic. If it is epistemic, then it only represents our knowledge. As such, your problem vanishes, since there is no problem at having different knowledge in different reference frames (then, every reference frame would have a state according to its knowledge). Since the measurement outcomes are the same, nothing changes. | |
| Dec 23, 2014 at 22:25 | comment | added | neuronet | "Only if you are in a specified reference frame, it looks like there is an immediate influence of one particle on another." yes, and this was the question...what reference frame(s)? I think the answer, as it stands, needs work (for one, within the formalism of nonrelativistic QM, with state vector reduction there is change at two locations at hte same time). Is there an expert on relativistic quantum theory here? | |
| Dec 23, 2014 at 15:52 | comment | added | senderle | I think you could put this in a different way and say that this isn't true temporal simultaneity, but a kind of logical simultaneity. So for example, you might say that the instant you accept that the Peano axioms are true, you simultaneously accept that all the theorems they prove are also true. But that's not something that actually happens in time; it's a logical, not a physical consequence. | |
| Dec 23, 2014 at 14:34 | comment | added | neuronet | @Martiin But when you make a measurement at point A, doesn't the mathematical description of what is happening at point B also change? State vector reduction doesn't just have a local influence, does it? | |
| Dec 23, 2014 at 14:13 | vote | accept | Bob | ||
| Dec 23, 2014 at 13:25 | comment | added | HolgerFiedler | This is a clear message. The uncertainty is in our knowledge about which particle is in which state. the particles are entangled since they are produced together. Perhaps somebody learned it by an other way, but the result of both thoughts are the same. So we not use the easier one? | |
| Dec 23, 2014 at 12:43 | history | answered | Martin | CC BY-SA 3.0 |