How stable/fragile is Quantum Entanglement? with respect to time, space and various events. Space - We know that experiments have validated QE working across say 150 kms and it is generally believed that they can work across very large distances. Does gravity effect QE over large distances? Time - How long can Alice and Bob keep their entangled photons bouncing of mirrors? (if that is how entangled photons are kept trapped) The interesting part is that between the two entangled photons there is so much background noise (in the form of EM radiations, other energy forms, matter and the various fundamental forces) yet entanglement survives. Yet QE "breaks" as soon as we try to measure one of the twins and it's believed, by some, that the photons at that point get entangled with something else (like parts of the measurement apparatus). It seems as if entangled particles are "connected" via a different mechanism/channel/dimension? and hence the noise does not effect them, yet events like measurement/detection does?