the Einstein–Podolsky–Rosen paradox

The Einstein–Podolsky–Rosen (EPR) paradox is a thought experiment that questions the completeness of quantum mechanics. Proposed in 1935, it describes a scenario where two particles are entangled, meaning their properties are linked regardless of the distance between them. If one particle is measured, the other instantly reflects that measurement, suggesting faster-than-light communication. Einstein saw this as a problem, arguing that if quantum mechanics allowed this, it implied "spooky action at a distance." The EPR paradox raises fundamental questions about reality, measurement, and the nature of information in quantum physics, challenging our understanding of how the universe operates.