On 30/11/2017 10:18 pm, Quentin Anciaux wrote:
2017-11-30 12:08 GMT+01:00 Bruce Kellett <[email protected] <mailto:[email protected]>>:On 30/11/2017 9:53 pm, [email protected] <mailto:[email protected]> wrote:On Wednesday, November 29, 2017 at 10:40:36 PM UTC, Bruce wrote: On 30/11/2017 5:31 am, John Clark wrote: On Tue, Nov 28, 2017 at 10:59 PM, Bruce Kellett <[email protected]> wrote: > I see no reason all the Everett worlds have the same physics, > Everettian worlds follow from assuming that the Schrödinger equation applies everywhere without exception, so that all physical evolution is unitary. A change in the underlying physics -- such as a change in the value of fundamental constants, Planck's constant or Newton's constant for example -- would not be unitary, so cannot occur in MWI. Why can't it be unitary?? Show me why if Newton's constant had any value other than 6.754* 10^-11 m3 kg^−1 s^−2 the sum of all quantum probabilities would no longer add up to exactly 1. If you can really do that then you've just derived Newton's constant directly from first principles and you should but a ticket to Stockholm right now because you're absolutely certain to win the next nobel Prize. Although unitarity does mean that probabilities always sum to unity, that is a consequence of unitary evolution, not a definition of it. A unitary transformation is one that can be reversed: so the unitary operator U can be written as exp(-iH), for example, and the complex conjugate (or the adjoint for hermitian operators) is the inverse transformation.* * * Considering the evolution of the wf, if there exists a DE that describes the collapse process, would it necessarily be nonlinear? Is nonlinear a problem; that is, what is the downside to nonlinear? How would it effect the issue of hidden variables? TIA, AG *Collapse would be non-linear and non-unitary -- intrinsically non-reversible. This is not necessarily a problem since there are plenty of non-linearities in physics. It has nothing to do with hidden variables. How could that be compatible with delayed choice experiment ?
Non-locality. As Zeilinger says: "Any explanation of what goes on in a specific individual observation of one photon has to take into account the whole experimental apparatus of the complete quantum state consisting of both photons, and it can only make sense after all information concerning complementary variables has been recorded."
arXiv:1206.6578 Bruce
Quentin
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