I also went through a phase where quantum entanglement seemed mundane and easily explained. However, I realized that this was merely because I was taking the analogies too literally.<p>The key difference between a bag of coins and a microscopic quantum system is that the contents of the bag before being observed is <i>unknown</i>, whereas the quantum state is actually <i>indeterminate</i>. By observing one entangled particle, you force the other to also take on a definite state. Read up on Bell&#x27;s inequality for the experimental justification of this idea.