An "EPR paper" refers to a scientific article that discusses the Einstein-Podolsky-Rosen (EPR) paradox, which was introduced in 1935 by Albert Einstein, Boris Podolsky, and Nathan Rosen. The paper aimed to highlight what they perceived as the incompleteness of quantum mechanics by presenting a thought experiment involving entangled particles. The EPR paper argues that if quantum mechanics is complete, then it implies "spooky action at a distance," where the measurement of one particle instantaneously affects another, regardless of the distance separating them. This concept has sparked extensive debate and research in the field of quantum physics, leading to further developments in our understanding of quantum entanglement.