speed of "transmission" in quantum entanglement when we "collapse the wave-function" via observing one of the entangled photons: is the transfer of the collapse information instantaneous (to the twin photon) or a few/many orders of magnitude of speed of light? lets say we observe one of the entangled photons (A) to be spin up. we know that the other photon (B) will be spin down. let's say both the photons are (time-space) separated by 10 light years. how long does it take for photon B to be spin down (collapse into a definite state) once photon A has been observed to be spin up? is the "transmission of the wave function collapse from one photon to its twin photon" instantaneous or so fast that it appears to be instantaneous? in other words how fast does the collapse of the wave function travel in a "bi-photon"?