This is a physics question but since it is on a 'universal' scale, I will ask it here. Quantum entanglement. I was watching a panel discussion with Leonard Suskind and others leading theoretical physicists....also watched a Nova program presented by David Green, etc. In both there was a variation of a comment that two entangled particles would act entangled whether they were in the next room or across the Universe. A question. Since no particles have been measured at any significant distance apart, how do we know this? Is it just a general assumption? How do we know that on a cosmological scale that the relationship between two entangled particles wouldn't diminish by (just hypothetical example) 1% over a trillion kilometers and eventually reduce to nothing? Or that entanglement just suddenly ceases (like a half life) a billion light years distance?