It means that a system in a superposition is in one of the states defining the superposition, but we don't know which one. Brent alleged it is "exactly wrong". I'd like an argument why that's the case, if it is. Does it follow from Bell experiments? TY, AG
Can we say that the observable has a DEFINITE value between two measurements? 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'. 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 psi = sqrt(1/2)[(s+)_z +(s-)_z] = (s+)_x. Now let us imagine that the state psi = sqrt(1/2)[(s+)_z +(s-)_z] is not a pure state but a mixture. In this case we might also think that - before measurement - the particle has a DEFINITE value, of the z-projection of the spin, let us say say [(s+)_z] OR [(s-)_z]. But, in this case, measuring the x-component of the spin, we would find 50% 'up'and 50% 'down'. But the real outcome says 100% 'up'. -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/432172729.282549.1728808022591%40mail1.libero.it.
