Quantum entanglement is one of the strangest phenomena of quantum physics, so strange that there is not yet one explanation of how it works, yet we have already found out how to take advantage of that phenomenon. The following video animation is a powerful tool for you to understand what quantum entanglement is, in a very comprehensible way.

## Quantum Entanglement: A Mysterious Connection

Quantum Entanglement refers to the enigmatic phenomenon in which pairs or groups of particles become interlinked in such a way that the quantum state of one particle cannot be described independently of the others. When entangled, particles maintain this deep connection regardless of the distance between them, instantaneously responding to changes in one another’s state. This peculiar behavior transcends classical physics, provoking intense curiosity and becoming a foundation for emerging quantum technologies, such as quantum computing and cryptography.

## Bell Inequality: Testing the Limits of Quantum Theory

The Bell Inequality, formulated by physicist John Bell in the 1960s, serves as a mathematical tool to investigate the validity of local hidden-variable theories—those which attempt to explain quantum correlations through unseen, classical mechanics. By devising experiments that test the correlations between entangled particles, Bell’s theorem reveals when these correlations surpass the constraints imposed by classical physics. This finding provides strong evidence for the fundamentally non-local and quantum nature of our universe, as it demonstrates that no local hidden-variable theory can account for the observed correlations in entangled particles.

## The EPR Paradox: Unsettling the Quantum Realm

The EPR Paradox, named after its creators—Albert Einstein, Boris Podolsky, and Nathan Rosen—emerged in 1935 as a powerful critique of the prevailing understanding of quantum mechanics. The trio’s thought experiment involved entangled particles separated by vast distances, and according to quantum mechanics, the measurement of one particle’s properties would instantaneously determine the other’s. This apparent “spooky action at a distance” troubled Einstein, who believed it violated the principles of locality and realism. The EPR Paradox spurred intense debate and research, ultimately leading to the formulation of Bell’s theorem and the discovery that the universe appears to embrace the strange, counterintuitive behavior exhibited by entangled particles.

Extensive information about: Bell’s Theorem | Quantum Entanglement | EPR Paradox

Video creator & source: Eugene Khutoryansky