4 ms·

As an non expert, aren't there ontological interpretations too? You say QM is epistemic, but is that referencing the Copenhagen Interpretation as commonly taugh

by meroes 6y ago

As an non expert, aren't there ontological interpretations too? You say QM is epistemic, but is that referencing the Copenhagen Interpretation as commonly taught? I know probability and unpredictablity don't go away, but MWI is closer to an ontologic theory no? I mean as far as science can claim to be ontological. And similarly for nonlocality. Is it only ontological? I feel like many worlds would say one thing vs copenhagen. And how do non traversible string theoretic wormholes reprsenting entanglement a la Susskind fit in if the theory can only be about epistemic knowledge.

Filligree 6y ago
The Schrodinger equation has no random terms. Accordingly, quantum mechanics isn't probabilistic. If you take it literally, it describes a universe which constantly splits (from a classical perspective), resulting in apparent randomness because you only remember one branch, but you exist in all of them. That's many-worlds. The pilot wave interpretation adds "Also, only one of them is real; the rest get 'computed' by reality, but any people you think it's computing are philosophical zombies." The Copenhagen interpretation states that all but one branch spontaneously cease to exist once a physicist looks at it. More or less. Really, just anything that's sufficiently coupled to the environment; physicists are a sure way to ensure that. The choice of which branch remains is random. Nobody really believes the Copenhagen interpretation, but it gives correct predictions so long as you don't try to explain why any of that should happen. ... Mostly. There's a cottage industry of trying to prevent decoherence in larger and larger objects, which makes it look less and less reasonable as the list of exceptions grows.
- meroes 6y ago
  While yes the SE is 100% deterministic, no outcome of an experiment is predetermined beyond giving probabilities. That's part of the mystery, where to insert the probability. Is it subjective or objective?
Kednicma 6y ago
As a fellow non-expert, I use tables like [0] to help keep everything straight. Yes, the Copenhagen interpretation says that the wavefunctions we manipulate are epistemic; they exist in our mind and on the blackboard but not necessarily IRL. The epistemic toy theory [1] makes this concept very concrete, although note that that theory has hidden local variables and thus doesn't correctly implement Bell/KS/Free Will. Yes, MWI is quite ontic; it's probably the most ontic that a QM interpretation can be, since it insists that all possibilities exist. Just like modal realism, MWI is the most extreme of the phrasings in that direction. Non-locality sadly isn't negotiable anymore. Bell's inequalities have been violated in laboratories well enough to my satisfaction [2], so theories that can't handle it need to be fully rejected. I'm not sure what's left; maybe the transactional interpretation? [0] https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#Comparisons https://en.wikipedia.org/wiki/Interpretations_of_quantum_mec... [1] https://arxiv.org/abs/quant-ph/0401052 https://arxiv.org/abs/quant-ph/0401052 [2] https://en.wikipedia.org/wiki/Bell_test_experiments https://en.wikipedia.org/wiki/Bell_test_experiments
- meroes 6y ago
  You say nonlocality isn't negotiable but I think one of Bell's assumptions isn't met in MW, namely single outcome of experiment. I think this is shown in that table as the local dynamics column. But then without nonlocality nor hidden variables, I truly am at a loss how quantum computers even work according to MWI. But I know this area gets so complex so fast.

by meroes 6y ago

Filligree 6y ago

The Schrodinger equation has no random terms. Accordingly, quantum mechanics isn't probabilistic. If you take it literally, it describes a universe which constantly splits (from a classical perspective), resulting in apparent randomness because you only remember one branch, but you exist in all of them. That's many-worlds. The pilot wave interpretation adds "Also, only one of them is real; the rest get 'computed' by reality, but any people you think it's computing are philosophical zombies." The Copenhagen interpretation states that all but one branch spontaneously cease to exist once a physicist looks at it. More or less. Really, just anything that's sufficiently coupled to the environment; physicists are a sure way to ensure that. The choice of which branch remains is random. Nobody really believes the Copenhagen interpretation, but it gives correct predictions so long as you don't try to explain why any of that should happen. ... Mostly. There's a cottage industry of trying to prevent decoherence in larger and larger objects, which makes it look less and less reasonable as the list of exceptions grows.

meroes 6y ago
While yes the SE is 100% deterministic, no outcome of an experiment is predetermined beyond giving probabilities. That's part of the mystery, where to insert the probability. Is it subjective or objective?

Kednicma 6y ago

As a fellow non-expert, I use tables like [0] to help keep everything straight. Yes, the Copenhagen interpretation says that the wavefunctions we manipulate are epistemic; they exist in our mind and on the blackboard but not necessarily IRL. The epistemic toy theory [1] makes this concept very concrete, although note that that theory has hidden local variables and thus doesn't correctly implement Bell/KS/Free Will. Yes, MWI is quite ontic; it's probably the most ontic that a QM interpretation can be, since it insists that all possibilities exist. Just like modal realism, MWI is the most extreme of the phrasings in that direction. Non-locality sadly isn't negotiable anymore. Bell's inequalities have been violated in laboratories well enough to my satisfaction [2], so theories that can't handle it need to be fully rejected. I'm not sure what's left; maybe the transactional interpretation? [0] https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#Comparisons https://en.wikipedia.org/wiki/Interpretations_of_quantum_mec... [1] https://arxiv.org/abs/quant-ph/0401052 https://arxiv.org/abs/quant-ph/0401052 [2] https://en.wikipedia.org/wiki/Bell_test_experiments https://en.wikipedia.org/wiki/Bell_test_experiments

meroes 6y ago
You say nonlocality isn't negotiable but I think one of Bell's assumptions isn't met in MW, namely single outcome of experiment. I think this is shown in that table as the local dynamics column. But then without nonlocality nor hidden variables, I truly am at a loss how quantum computers even work according to MWI. But I know this area gets so complex so fast.