Quantum Measurement. The spooky point is usually that, in the right circumstances, when you then send these particles to opposite sides on the universe, executing a measurement on a single will instantaneously affect the outcome of the measurement on another, even if there is usually no data exchanged among them. https://directoryindexer.com/listings12758116/quantum-of-the-seas-the-5-second-trick-for-quantum-theory