> Il 16 novembre 2018 alle 10.19 agrayson2...@gmail.com ha scritto: > > > > On Thursday, November 15, 2018 at 2:14:48 PM UTC, scerir wrote: > > > > > > > > > > > Il 15 novembre 2018 alle 14.29 agrays...@gmail.com ha > > scritto: > > > > > > > > > > > > On Thursday, November 15, 2018 at 8:04:53 AM UTC, scerir > > > wrote: > > > > > > > > > > > > > > Imagine a spin-1/2 particle described by the state psi > > > > = sqrt(1/2) [(s+)_z + (s-)_z] . > > > > > > > > If the x-component of spin is measured by passing the > > > > spin-1/2 particle through a Stern-Gerlach with its field oriented along > > > > the x-axis, the particle will ALWAYS emerge 'up'. > > > > > > > > > > > > > > Why? Won't the measured value be along the x axis in both > > > directions, in effect Up or Dn? AG > > > > > > > > > > "Hence we must conclude that the system described by the |+>x state > > is not the > > same as a mixture of atoms in the |+> and !-> states. This means > > that each atom in the > > beam is in a state that itself is a combination of the |+> and |-> > > states. A superposition > > state is often called a coherent superposition since the relative > > phase of the two terms is > > important." > > > > .see pages 18-19 here https://tinyurl.com/ybm56whu > > > > > > Try answering in your own words. When the SG device is oriented along the > x axis, now effectively the z-axix IIUC, and we're dealing with > superpositions, the outcomes will be 50-50 plus and minus. Therefore, unless > I am making some error, what you stated above is incorrect. AG >
sqrt(1/2) [(s+)_z +(s-)_z] is a superposition, but since sqrt(1/2) [(s+)_z +(s-)_z] = (s+)_x the particle will always emerge 'up' > > > > > > > > > > > > > > > > > > > > > > > In fact (s+)_z = sqrt(1/2) [(s+)_x + (s-)_x] > > > > > > > > and (s-)_z = sqrt(1/2) [(s+)_x - (s-)_x] > > > > > > > > (where _z, _x, are the z-component and the x-component > > > > of spin) > > > > > > > > so that psi = sqrt(1/2)[(s+)_z +(s-)_z] = (s+)_x. > > > > (pure state, not mixture state).. > > > > > > > > AGrayson2000 asked "If a system is in a superposition > > > > of states, whatever value measured, will be repeated if the same system > > > > is repeatedly measured. But what happens if the system is in a mixed > > > > state?" > > > > > > > > Does Everett's "relative state interpretation" show how > > > > to interpret a real superposition (like the above, in which the > > > > particle will always emerge 'up') and how to interpret a mixture (in > > > > which the particle will emerge 50% 'up' or 50% 'down')? > > > > > > > > > > > > > > > > > > > > -- > > > 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 everything-li...@googlegroups.com. > > > To post to this group, send email to > > > everyth...@googlegroups.com. > > > Visit this group at > > > https://groups.google.com/group/everything-list > > > https://groups.google.com/group/everything-list . > > > For more options, visit https://groups.google.com/d/optout > > > https://groups.google.com/d/optout . > > > > > > > > > > > > > > -- > 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 everything-list+unsubscr...@googlegroups.com > mailto:everything-list+unsubscr...@googlegroups.com . > To post to this group, send email to everything-list@googlegroups.com > mailto:everything-list@googlegroups.com . > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
