41
Physics, Astronomy & Cosmology / Re: Quantum Entanglement and Interstellar Communication.
« on: 02/12/2023 17:54:05 »
A couple of clarifications, based on my limited knowledge of the issue.
Anyway, your wording implies that the unmeasured particle actually has a spin orientation, which most interpretations deny.
All that said, the glove analogy (a classical example) still satisfies pretty much all of the above points. I separate the gloves in envelopes unopened, When one is opened, that person instantly knows the contents of the other envelope. It's a epistemological thing, not a metaphysical one. The glove system is classical, so metaphysically, there is in fact a left glove in this envelope and a right in the other. No superposition. We just don't know which is which.
Quantum systems go further than that. The EPR paradox showed that quantum entanglement cannot be classical like the gloves. I'm not going to attempt to explain that since I'd get it wrong. Look up the paradox or Bell's theorem if you want the detail. They are probably well beyond what Zero want's to know. They are beyond my capability to convey correctly without just copying text from a website.
We will assume that the property we are going to look at is the spin of the particles.We are measuring the spin relative to some particular axis. Only if both measurements use the same axis will the measurements be fully correlated. If perpendicular axes are used, there will be no correlation. If something between is used (45 degrees say), there will be partial correlation.
The 2 particles are separated by 10 million miles. Each location has a detector that will measure the particles spin direction (up or down).
Quote
5. Once either particle is measured they are no longer entangled.Sort of. The measuring system is effectively entangled with the unmeasured particle, which is why you can know what the measurement will be if it ever gets done. I think if you measure a particle along the same axis twice in a row, you'd get the same result, so in that way of looking at it, the two particles remain entangled, but the entanglement is now restricted to the axis that has been chosen, so a subsequent measurement along a perpendicular axis isn't going to be correlated with the unmeasured particle.
Quote
6. Once you measure the orientation of your particle you instantly know the orientation of the other particle.You instantly know the outcome of a measurement of the other particle along the same axis, regardless of if it has already been done or will be done (a frame dependent distinction). The far guy of course knows none of this, so from his point of view, the outcome is still totally random.
Anyway, your wording implies that the unmeasured particle actually has a spin orientation, which most interpretations deny.
All that said, the glove analogy (a classical example) still satisfies pretty much all of the above points. I separate the gloves in envelopes unopened, When one is opened, that person instantly knows the contents of the other envelope. It's a epistemological thing, not a metaphysical one. The glove system is classical, so metaphysically, there is in fact a left glove in this envelope and a right in the other. No superposition. We just don't know which is which.
Quantum systems go further than that. The EPR paradox showed that quantum entanglement cannot be classical like the gloves. I'm not going to attempt to explain that since I'd get it wrong. Look up the paradox or Bell's theorem if you want the detail. They are probably well beyond what Zero want's to know. They are beyond my capability to convey correctly without just copying text from a website.
The following users thanked this post: Zer0