When two particles become entangled, their quantum states become correlated in such a way that measuring one particle's state can provide information about the other, regardless of the distance between them. This correlation is established during the process of entanglement and is maintained even when the particles are separated by large distances.
The instantaneous change in the quantum field associated with an entangled particle when it is observed is a consequence of the non-local nature of entanglement. According to quantum mechanics, the wave function describing the entangled particles is a superposition of all possible states. When one particle is measured, its wave function collapses to a specific state, and due to the entanglement, the other particle's wave function also collapses instantaneously to a correlated state.
However, it is important to note that this apparent instantaneous change does not violate the principles of relativity or allow for faster-than-light communication. The collapse of the wave function occurs instantaneously, but the information obtained from the measurement cannot be used to transmit signals faster than the speed of light. This is because the measurement outcomes are random and cannot be controlled or manipulated to transmit information.
The phenomenon of instantaneous changes in the quantum field through space when an entangled particle is observed is still a topic of ongoing research and discussion in the field of quantum physics. Various interpretations and theories attempt to explain the mechanism behind entanglement and its non-local effects, such as the Copenhagen interpretation, many-worlds interpretation, and pilot-wave theory. However, the exact nature of entanglement and its consequences are still the subject of scientific investigation.