The apparent "spooky action at a distance" of quantum entanglement, where particles separated by vast distances instantaneously influence each other's properties, has puzzled scientists for decades. According to the principles of quantum mechanics, information cannot be transmitted faster than the speed of light, so how does this instantaneous correlation happen?
The currently accepted explanation for quantum entanglement is that it is a fundamental property of quantum systems and is a consequence of the way quantum mechanics describes the behavior of particles at the microscopic scale. This phenomenon has been extensively tested and confirmed through various experiments, and its predictions have been found to be in excellent agreement with experimental observations.
The key points to understand about quantum entanglement are:
Non-locality: Quantum entanglement is a form of non-locality, meaning that the correlations between entangled particles exist instantaneously regardless of the distance separating them. This seemingly contradicts our classical intuition, where information cannot travel faster than light.
No communication: Despite the appearance of instantaneous influence, quantum entanglement cannot be used to transmit information faster than the speed of light. The entangled particles themselves do not carry any useful information until measured, and the outcome of any measurement is inherently random and cannot be predicted in advance.
No hidden variables: The concept of hidden variables suggests that there might be unknown properties or information carried by particles that determine their behavior. However, in the mid-20th century, physicist John Bell proposed and subsequently experimental tests (Bell tests) have shown that certain correlations between entangled particles violate the inequalities that would be expected if hidden variables were responsible for the observed behavior. These tests have consistently supported the predictions of quantum mechanics, indicating that there are no hidden variables that govern quantum entanglement.
The prevailing interpretation of quantum entanglement is that it represents an intrinsic non-local connection between entangled particles. When two particles become entangled, their quantum states become linked in such a way that the state of one particle is directly related to the state of the other, regardless of the distance between them. However, this entangled state cannot be used to transmit information, and its true nature remains one of the profound mysteries of quantum mechanics.