On 5/22/2018 3:46 PM, [email protected] wrote:
On Tuesday, May 22, 2018 at 10:41:11 PM UTC, [email protected] wrote: On Tuesday, May 22, 2018 at 10:06:39 PM UTC, Brent wrote: On 5/22/2018 6:39 AM, [email protected] wrote:I'm OK with getting rid of the projection operator. Are you now claiming information is lost or inaccessible in these orthogonal subspaces and therefore quantum measurements cannot be reversed?They are inaccessible to the people of any one world of the MWI. No! Irreversible FAPP! Think heat bath or Bucky Balls. https://en.wikipedia.org/wiki/Quantum_decoherence <https://en.wikipedia.org/wiki/Quantum_decoherence> Examples of non-unitary modelling of decoherence Decoherence <https://en.wikipedia.org/wiki/Decoherence> can be modelled as a non-unitary <https://en.wikipedia.org/wiki/Unitary_operator> process by which a system couples with its environment (although the combined system plus environment evolves in a unitary fashion).^[4] <https://en.wikipedia.org/wiki/Quantum_decoherence#cite_note-Lidar_and_Whaley-4> Thus the dynamics of the system alone, treated in isolation, are non-unitary and, as such, are represented by irreversible transformations <https://en.wikipedia.org/wiki/Irreversibility> acting on the system's Hilbert space <https://en.wikipedia.org/wiki/Hilbert_space>, H {\displaystyle {\mathcal {H}}} {\mathcal {H}}. Since the system's dynamics are represented by irreversible representations, then any information present in the quantum system can be lost to the environment or heat bath <https://en.wikipedia.org/wiki/Heat_bath>. Alternatively, the decay of quantum information caused by the coupling of the system to the environment is referred to as decoherence.^[3] <https://en.wikipedia.org/wiki/Quantum_decoherence#cite_note-Bacon-3> Thus decoherence is the process by which information of a quantum system is altered by the system's interaction with its environment (which form a closed system), hence creating an entanglement <https://en.wikipedia.org/wiki/Quantum_entanglement> between the system and heat bath (environment). As such, since the system is entangled with its environment in some unknown way, a description of the system by itself cannot be made without also referring to the environment (i.e. without also describing the state of the environment).Notice that this doesn't explain how one gets to a single result.I did, but you're avoiding the key point; if the theory is on the right track, and I think it is, quantum measurements are irreversible FAPP. The superposition is converted into mixed states, no interference, and no need for the MWI.
You're still not paying attention to the problem. First, the superposition is never converted into mixed states. It /approximates/, FAPP, a mixed state/in some pointer/ basis (and not in others). Second, even when you trace over the environmental terms to make the cross terms practically zero (a mathematical, not physical, process) you are left with different outcomes with different probabilities. CI then just says one of them happens. But when did it happen?...when you did the trace operation on the density matrix?
I still don't get it -- why you and Bruce keep resorting to the MWI to deny reversible FAPP, when both of you have huge disrespect for the MWI. AG
I have huge disrespect for Donald Trump. Theories of physics I regard with relative equanimity.
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