But here is the difference, familiar to many yet still deeply shocking: in the ordinary classical description, after you flip the coin but before you look, the coin is either heads or tails, you simply don’t know which. By contrast, in the quantum description, prior to examining the whereabouts of a particle like an electron that has a 50 percent chance of being here and a 50 percent chance of being there, the particle is not either here or there. Instead, quantum mechanics says the particle is hovering in a fuzzy mixture of being both here and there.
