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. This correlation is non-local, meaning that the entangled particles can be separated by vast distances and still exhibit this connection.
While entanglement may seem to imply instantaneous communication or information transfer, it cannot be used for faster-than-light communication due to a fundamental principle in physics known as the no-communication theorem. This theorem, based on the principles of relativity, states that it is impossible to use entanglement to transmit information faster than the speed of light.
The reason for this limitation is that even though the states of entangled particles are instantaneously correlated, the actual measurement or observation of the entangled particles' states cannot be predetermined or controlled. When one particle's state is measured, it "collapses" into a definite value, but the other particle's state remains uncertain until it is measured as well. The measurement outcomes on both sides are random and do not convey any meaningful information until they are compared after the fact.
Since the outcomes of measurements on entangled particles are random and cannot be controlled or manipulated to transmit information in a predetermined manner, it is not possible to use entanglement for faster-than-light communication. Any attempt to use entanglement to communicate faster than the speed of light would violate the principles of causality and special relativity.
It's important to note that while entanglement itself cannot be used for faster-than-light communication, it is still a fascinating and valuable phenomenon in quantum mechanics. It has implications for quantum computing, quantum cryptography, and our understanding of fundamental aspects of quantum theory.