Interpretation of quantum mechanics
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 possibility of a large range of interpretations of quantum mechanics becomes clearer once it is observationally and mathematically demonstrated that no theory of small-scale physics can have all of the properties one would like quantum mechanics to have.
One intuitively would like a physical theory
- 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 hidden variables that determine this outcome;
- that predicts only one universe.
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 have been taken as indicating that quantum mechanics is correct. The experiments are known to have "loopholes", however, so the question remains open, with attempts to devise "loophole-free" experiments continuing. Another possibility which is also under investigation is that Bell's theorem itself 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 |
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".
List of physics topics : Quantum mechanics, Quantum indeterminacy, Bell's theorem, Bohm interpretation, Copenhagen interpretation, Many-worlds interpretation, Quantum computation, Unsolved problems in physicsSee also