Quantum entanglement is one of the more bizarre theories to come out of the study of quantum mechanics — so strange, in fact, that Albert Einstein famously referred to it as “spooky action at a distance.”

Essentially, entanglement involves two particles, each occupying multiple states at once — a condition referred to as superposition. For example, both particles may simultaneously spin clockwise and counterclockwise. But neither has a definite state until one is measured, causing the other particle to instantly assume a corresponding state.

The resulting correlations between the particles are preserved, even if they reside on opposite ends of the universe.

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