Interpretation of quantum mechanics
From Wikinfo
Quantum mechanics is a physical theory which is extremely non-intuitive. The equations have been very successful in predicting experimental results, but there have been a wide range of interpretations of what those equations mean.
The need for a large range of interpretations of quantum mechanics becomes clearer once it is mathematically demonstrated that no quantum theory can have all of the properties one would like quantum mechanics to have.
One inituitively would like a theory of quantum mechanics
- that is complete and not requiring any outside theory
- that is local in that the events at one point are only affected by nearby areas
- that is deterministic which is that given one set of circumstances, there is only one possible outcome
- that has no hidden variables
- that predicts only one universe
However, Bell's theorem appears to prevent quantum mechanics from having all of these properties. Which property is removed results in different interpretations of quantum mechanics.
One other possibility that has been explored is that quantum mechanics is wrong, and that the actual theory of the universe does have all of the properties that one would like a theory to have. This possiblity has been tested by numerous experiments, all of which indicate that quantum mechanics is correct. Another possibility which is also under investigation is that Bell's theorem has some loophole or hidden assumption and is not correct.
At first glance, all of the interpretations appear to produce the same physical results, which makes distinguishing between them on the basis of experiment to be impossible. Nevertheless, there is active research in attempting to come up with experimental tests which would allow differences between the interpretations to be experimentally tested.
Some of the most common interpretations are summarized here:
| Interpretation | Deterministic? | Waveform real? | One Universe? |
Avoids hidden variables? |
Local? | Avoids collapsing wavefunctions? |
|---|---|---|---|---|---|---|
| Copenhagen interpretation (Waveform not real) |
No | No | Yes | Yes | No | Yes |
| Copenhagen interpretation (Waveform real) |
No | Yes | Yes | Yes | No | No |
| Consistent Histories | No | No | Yes | Yes | Yes | Yes |
| Consciousness causes Collapse | No | Yes | Yes | Yes | No | No |
| Everett many-worlds interpretation | Yes | Yes | No | Yes* | Yes | Yes |
| Bohm interpretation | Yes | No | Yes | No | No | Yes |
*Many Worlds has no hidden variables, except for the multiple worlds themselves.
Each interpretation has many variants. It is very difficult to get a precise definition of the Copenhagen Interpretation - in the table above, 2 variants of the Copenhagen Interpretation are shown - one that regards the waveform as being a tool for calculating probabilties only, and the other regards the waveform as an "element of reality".
See also
List of physics topics : Quantum mechanics, Quantum indeterminacy, Bell's theorem, Bohm interpretation, Copenhagen interpretation, Many-worlds interpretation, Unsolved problems in physics
Other: Quarantine (novel)
External Links
References
- Adapted from the Wikipedia article, "Interpretation_of_quantum_mechanics" http://en.wikipedia.org/wiki/Interpretation_of_quantum_mechanics, used under the GNU Free Documentation License
