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Bell's theorem demands that you give up locality or realism. Either is fine; historically speaking it's just been easier to give up realism. Of course physicist

by Herring 17y ago

Bell's theorem demands that you give up locality or realism. Either is fine; historically speaking it's just been easier to give up realism. Of course physicists found a way to keep both (by splitting the observer up), & MWI's increasing popularity reflects this. In my view it's useless to argue about interpretations. Last I checked they had the same predictions.

Estragon 17y ago
In my view it's useless to argue about interpretations. Last I checked they had the same predictions. Not true at all. If the superposition in the QM formalism merely represents our ignorance about the system's state, rather than an objective reality, then QC loses the massive parallelism which is supposed to make it so much more efficient than classical computation.
- Herring 17y ago
  Well nobody argues the wave function represents our ignorance about the system's state. It's certainly not in the Copenhagen interpretation anyway. The wave function sacrifices realism.
  - Estragon 17y ago
    In the Copenhagen interpretation, the wave function represents our ignorance of what the system's state will become when observed, but it's taken as an accurate description of the system's actual state prior to observation. That is the point of the "Schroedinger's cat" paradox: that under the Copenhagen interpretation, the cat actually is in a superposition of alive and dead states, until someone looks in the box. Quantum computation crucially depends on the objective reality of this superposition. It seems likely to me that the superposition in the formalism actually just represents our ignorance of the system's state, not the state itself.
    - Herring 17y ago
      > It seems likely to me that the superposition in the formalism actually just represents our ignorance of the system's state, not the state itself. Again, nobody argues that. It's possible to experimentally distinguish between the two situations (Bell's theorem). This is a bit of a strawman. Besides the wave function is a complex vector. It can't represent ignorance. You have to take |ψ|2 to get a real value.

by Herring 17y ago

Estragon 17y ago

In my view it's useless to argue about interpretations. Last I checked they had the same predictions. Not true at all. If the superposition in the QM formalism merely represents our ignorance about the system's state, rather than an objective reality, then QC loses the massive parallelism which is supposed to make it so much more efficient than classical computation.

Herring 17y ago
Well nobody argues the wave function represents our ignorance about the system's state. It's certainly not in the Copenhagen interpretation anyway. The wave function sacrifices realism.
- Estragon 17y ago
  In the Copenhagen interpretation, the wave function represents our ignorance of what the system's state will become when observed, but it's taken as an accurate description of the system's actual state prior to observation. That is the point of the "Schroedinger's cat" paradox: that under the Copenhagen interpretation, the cat actually is in a superposition of alive and dead states, until someone looks in the box. Quantum computation crucially depends on the objective reality of this superposition. It seems likely to me that the superposition in the formalism actually just represents our ignorance of the system's state, not the state itself.
  - Herring 17y ago
    > It seems likely to me that the superposition in the formalism actually just represents our ignorance of the system's state, not the state itself. Again, nobody argues that. It's possible to experimentally distinguish between the two situations (Bell's theorem). This is a bit of a strawman. Besides the wave function is a complex vector. It can't represent ignorance. You have to take |ψ|2 to get a real value.