If anyone here knows, how is quantum entanglement testing done? For instance, it is said that two entangled particles could be far apart, as in light years apart and their entangled state would still be intact. There is some discussion that information could be exchanged at rates faster than the speed of light. I've seen discussion that dissects the possibilities and shows that it can't be done. However, how is the claim backed up that two entangled particles can remain entangled even though they are light years apart? No one is able to separate an entangled pair by light years so is this just extrapolating from much smaller distances? In other words, is it just that the testers know of nothing that should unentangle the particles even should they be light years apart?