This view is however rather sharply contrasted by the loss of unitarity in quantum measurements, such as those I discussed in my Nov 2012 and Feb 2013 updates. So which is it? Is the world deterministic or not? Perhaps nobody knows, but I'll mix the deck a little bit.

Evolution of a wavefunction in a completely quantum mechanical system is unitary, this means that such a system is in priciple perfectly deterministic. Modern physics knows two major nonunitary cases. The measurement problem - the wave function collapse (exemplified by apparently indeterministic radioactive decay for example), and the black hole information paradox. Now it seems that at least Stephen Hawking and Leonard Susskind believes that black hole information paradox is or will be resolved in favor of information not being lost (this implying determinism).

If indeed there is no such thing as black hole information paradox then perhaps is it also true that wavefunction collapse will not lose information either and is fundamentally deterministic. How could it be? Didn't Bell's theorem kill all hope of determinism? Perhaps not, it only killed all hope of local hidden variables theories, but perhaps the hidden variables aren't local... and perhaps the ways in which the perfect description can be found has to do with the Holographic principle and black holes. Wouldn't that be something beautiful?

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