No matter how far away they are, particles of energy or matter can get entangled and interact predictably with one another. This phenomenon is known as entanglement in quantum theory.

In physics, the concept of entanglement refers to how particles of matter or energy can join up and interact predictably with one another, regardless of their distance from one another. Because of this inexplicable connection that they nevertheless maintain, particles, including electrons and photons, can get entangled with one another in pairs. Correlation is the term for this procedure. Considering the spin state of an entangled particle enables one to infer that the spin of the particle's partner or pair is in the opposing direction. If one particle, for instance, is spinning up, its counterpart is spinning down. It becomes even stranger because, to human understanding of superposition phenomena, one can measure a particle that simultaneously has an uneven spin state (up and down) while having no single direction of spin before measurement.