Quantum tunneling isn't as mysterious as popular discourse likes to make it sound.
Quantum tunneling involves barriers to movement. Think an insulator around a wire. Electrons can freely move throughout the bulk of the metal and even just a little bit outside of the metal, but they can't transfer to the atoms in the insulating material. However, if you have an arrangement like two pieces of metal separated by a very small bit of insulator, tunneling can become possible. Classical mechanics would say that any amount of insulator between conductors should be able to completely stop charge transfer between conductors no matter how small. However, the wave function that describes an electron's characteristics isn't just a single point. It is spread out a bit. If the insulating layer is small enough, sometimes the electron wave functions will span through the insulating layer and a small portion of it extends into the next conductor. This means that if we measure the charge state on both pieces of metal, every once in a while, the charge state of one will decrease at the same time that the charge state of the other increases by the value of 1 electron. Lots of factors change how often this happens, such as a strong electric field. So do we know where the electron has gone? Not specifically, but we know the charge states of the two regions and it is otherwise confined. Do we know if it is the same electron? No, electrons are completely indistinguishable, and this is actually a pretty important concept for quantum mechanics. But whether it is the same electron, or if there's some exchange that occurs during the tunneling doesn't really matter. We know that a charge transfer has occurred through a barrier without adding or removing energy.
all 7 comments