Einstein-Podolsky-Rosen paradox

The Einstein-Podolsky-Rosen (EPR) paradox is a thought experiment highlighting how two particles can become linked in such a way that measuring one instantly reveals information about the other, no matter the distance between them. This suggests a kind of "instant communication" that seems to defy the speed limit set by the speed of light, challenging our understanding of locality and realism in physics. Einstein found this unsettling, believing it indicated incomplete understanding of quantum mechanics. The paradox has since led to deeper exploration of quantum entanglement, a phenomenon now experimentally confirmed and fundamental to quantum physics.