Entanglement is a phenomenon in quantum mechanics where two or more particles become correlated in such a way that the state of one particle is dependent on the state of the other, regardless of the distance between them. When particles are entangled, measuring the state of one particle instantly determines the state of the other, even if they are far apart. This behavior has been experimentally confirmed through various quantum entanglement experiments.
The crucial aspect of entanglement is that it does not involve classical communication or any form of direct interaction between the particles. Instead, it is a consequence of the inherent nature of quantum mechanics.
According to quantum mechanics, particles do not possess definite properties, such as position or momentum, until they are measured. Instead, their properties exist in a superposition of all possible states until an observation collapses the superposition into a specific state.
When two particles become entangled, their individual states are no longer independent but become intertwined. The entangled particles form a unified quantum system with shared properties. As a result, measuring one particle "instantaneously" determines its state, and by extension, the state of the other entangled particle, regardless of the distance between them.
However, it's important to note that entanglement itself does not allow for faster-than-light communication or transfer of information. Even though the measurement on one particle instantaneously affects the other, it is not possible to use entanglement to transmit information or communicate signals faster than the speed of light. This is because the specific state of the entangled particles cannot be predetermined or controlled. It is only through a statistical analysis of many entangled particles that correlations emerge.
The precise mechanism by which entanglement works and how information is shared between entangled particles is still a topic of ongoing research and debate in quantum mechanics. Several interpretations and mathematical formalisms, such as wavefunction collapse, entanglement swapping, and quantum entanglement as a non-local correlation, have been proposed to explain this phenomenon.