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] > <javascript:>> 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 * > > So for changes in constants to be unitary, there needs to be a hermitian > operator that brings about these changes. But changes in constants only > make sense for dimensionless constants such as the fine structure constant, > and there is currently no theory as to how this would change in a unitary > manner. > > > >> > lets assume you're right, then the string theory multiverse must be larger > than the many worlds multiverse incorporating everything in Everett's > version and MORE; after all if it contains universes with radically > different laws of physics it must also contain more modest things like a > world where my coin came up heads instead of tails. > > > > > I would suggest that there is no such world. Whether a coin comes up head > or tails on a simple toss is not a quantum event; > > > Do you actually think reality can be neatly divided > > between quantum and non-quantum events? A unstable atom has a 50% chance > of decaying and producing a easily detectable high speed electron, if the > electron is detected a computer controlled robot arm turns my coin to > heads, if it detects no electron it turns my coin to tails. > > > Of course, if you set up a situation in which a quantum event is amplified > to give a difference in macroscopic outcomes, such as in Schrödinger's cat, > then you can say that the macroscopic uncertainty has a quantum origin. But > the majority of quantum events are not amplified in this way -- they simply > occur randomly in large numbers so that the expectation value is unaffected > by individual uncertainties. > > > > Also, in the Level I multiverse it is quite unlikely that the initial > conditions could differ to an extent such that everything was identical in > the two worlds up to your coin toss. > > > Quite > unlikely > events are going to happen if the number of universes is large enough, > and if there are a infinity of worlds then anything with a non-zero > probability is certain to happen in some universe. > > > Except events of measure zero. > > > > > > Worlds are not random objects, they follow the laws of physics, so given > some initial conditions, the future is determined i > > ... -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
