On Friday, July 25, 2025 at 7:30:04 AM UTC-6 John Clark wrote:
On Fri, Jul 25, 2025 at 7:00 AM Alan Grayson <agrays...@gmail.com> wrote: *> Can you write the spin state UP as a superposition of LEFT and RIGHT states, * *Yes.* *> and explain the physical reason that is possible?* *>>If we're working with spin-1/2 particles like an electron then the UP and DOWN states form one complete basis, while LEFT and RIGHT states form another complete basis. Since both are bases for the same two-dimensional Hilbert space, any state in one basis can be expressed as a linear combination of states in the other basis. But if you've not actually made a UP vs Down measurement then the particle is still in a superposition of UP and DOWN, and if you then make a measurement of Left vs Right then there's no way to ever know if the particle was ever originally UP or DOWN. That is very weird but that's the way nature behaves. * *> My problem is I can't imagine the geometry. AG* *Think of up-down as being the x-axis and right-left being the orthogonal Y-axis. An unmeasured electron is in a superposition, not necessarily 50-50, of up-down and left-right. If you knew exactly where that unmeasured electron should be on those two axes then you would know it's exact position and momentum, but that is impossible because if you measure the exact up-down then you have no idea of the left-right, and if you measure the left-right exactly then you have no idea of the up-down, although you can make approximate measurements of both. * * John K Clark See what's on my new list at Extropolis <https://groups.google.com/g/extropolis>* But before the measurement in the SG experiment, the electron is entirely in the Y-axis? What's the logic for inferring a superposition in this situation? AG -- 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 view this discussion visit https://groups.google.com/d/msgid/everything-list/cbaae467-1736-49cc-80b9-899cb3024672n%40googlegroups.com.
