3 ms·

> there can be no instantaneous influence, in the sense of a causal effect or transmission of information, from one particle to a distant entangled particle Di

> there can be no instantaneous influence, in the sense of a causal effect or transmission of information, from one particle to a distant entangled particle Didn't the Bell's theorem prove that wrong though? I.e. that there needs to be some sort of "hidden variables" for it to work?

leephillips 5y ago
More like the opposite of that. Bell’s theorem tells us that there are two choices: either QM is inherently non-local, or there are influences (hidden variables) that can operate faster than light. Although both choices are in a sense disturbing, most people realize that we have to accept the non-local option. If we do, everything still works, even if we might feel uncomfortable. If, however, we accept faster-than-light influences, nothing works.
- snarkypixel 5y ago
  Makes sense. And unless I'm mistaken, to be entangled, they have to be very close to each others at some point, right? And then we can send one of the pair far away and they'd still be entangled. I can imagine some sort of more fundamental link connecting the two, but it's still not breaking ftl
  - leephillips 5y ago
    Yes, the particles are prepared together, then separated. Experiments on entangled particles have now managed to keep them entangled while separating them by huge distances—many kilometers. Of course there is a link connecting them, which we express by saying they are “entangled”. But we may never be able to connect this with concepts that are intuitive from our experience with the classical world.
    - yourenotsmart 5y ago
      Non-locality is not just a problem of the classic world. There's no notion of it in the quantum mechanics world either. There's nothing in the math that suggests how can particles kilometers away can be connected "outside" space. And technically if they were, this would be apparent in many more ways than entanglement experiments, and it WOULD violate causality. General relativity also has no such concept as "simultaneous events" at distance. The very point of the theory is that event simultaneity is a meaningless concept at distance (any distance, but especially at large distance). So from scale cosmic to scale quantum, "non-local" is a meaningless concept, yet we have to just assume none of this matters and call the wave function collapse non-local, because that's the only way we decided the experiments make sense. So you're trying to handwave an issue away that's bigger than you admit. It implies space beyond space and time beyond time, where everything in the universe can happen simultaneously for two entangled particles regardless of where and when in that universe they happen to be. It's such an outrageous concept to introduce in this special case, with zero explanation, and without considering the larger implications it has, it honestly borders on The Avengers techno-babble about time travel in terms of how much sense it makes.
- yourenotsmart 5y ago
  Accepting the non-local option is not an ultimatum, given there are multiple competing interpretations of these mechanics, and non-locality is just ONE of them. You continue to insist the world has agreed in unison with the interpretation you personally like, but that's not the case. Do you realize many worlds doesn't require collapse?
  - leephillips 5y ago
    I’ve heard of it: https://arstechnica.com/science/2017/07/a-brief-history-of-quantum-alternatives/ https://arstechnica.com/science/2017/07/a-brief-history-of-q... Frankly, I don’t understand anything you‘re trying to say in your multiple replies to my comments, and I suggest you spare yourself any further effort in this direction.

leephillips 5y ago

More like the opposite of that. Bell’s theorem tells us that there are two choices: either QM is inherently non-local, or there are influences (hidden variables) that can operate faster than light. Although both choices are in a sense disturbing, most people realize that we have to accept the non-local option. If we do, everything still works, even if we might feel uncomfortable. If, however, we accept faster-than-light influences, nothing works.

snarkypixel 5y ago
Makes sense. And unless I'm mistaken, to be entangled, they have to be very close to each others at some point, right? And then we can send one of the pair far away and they'd still be entangled. I can imagine some sort of more fundamental link connecting the two, but it's still not breaking ftl
- leephillips 5y ago
  Yes, the particles are prepared together, then separated. Experiments on entangled particles have now managed to keep them entangled while separating them by huge distances—many kilometers. Of course there is a link connecting them, which we express by saying they are “entangled”. But we may never be able to connect this with concepts that are intuitive from our experience with the classical world.
  - yourenotsmart 5y ago
    Non-locality is not just a problem of the classic world. There's no notion of it in the quantum mechanics world either. There's nothing in the math that suggests how can particles kilometers away can be connected "outside" space. And technically if they were, this would be apparent in many more ways than entanglement experiments, and it WOULD violate causality. General relativity also has no such concept as "simultaneous events" at distance. The very point of the theory is that event simultaneity is a meaningless concept at distance (any distance, but especially at large distance). So from scale cosmic to scale quantum, "non-local" is a meaningless concept, yet we have to just assume none of this matters and call the wave function collapse non-local, because that's the only way we decided the experiments make sense. So you're trying to handwave an issue away that's bigger than you admit. It implies space beyond space and time beyond time, where everything in the universe can happen simultaneously for two entangled particles regardless of where and when in that universe they happen to be. It's such an outrageous concept to introduce in this special case, with zero explanation, and without considering the larger implications it has, it honestly borders on The Avengers techno-babble about time travel in terms of how much sense it makes.
yourenotsmart 5y ago
Accepting the non-local option is not an ultimatum, given there are multiple competing interpretations of these mechanics, and non-locality is just ONE of them. You continue to insist the world has agreed in unison with the interpretation you personally like, but that's not the case. Do you realize many worlds doesn't require collapse?
- leephillips 5y ago
  I’ve heard of it: https://arstechnica.com/science/2017/07/a-brief-history-of-quantum-alternatives/ https://arstechnica.com/science/2017/07/a-brief-history-of-q... Frankly, I don’t understand anything you‘re trying to say in your multiple replies to my comments, and I suggest you spare yourself any further effort in this direction.