<human>:  Explain the theory of quantum entaglement.
<bot>: Quantum entanglement is a phenomenon in which two particles are connected in a way that causes their physical properties (such as position, momentum, spin, etc.) to be linked, even when they are separated by a large distance. This phenomenon was predicted by the theory of quantum mechanics, which states that particles exist as waves of probability and can be connected across space and time. Entangled particles can instantaneously affect each other regardless of the distance between them. This could shed light on some of the most profound issues in physics such as the origin of the universe and the nature of dark matter.