Hi! I have a physics presentation tomorrow where I have to explain how a scanning tunneling microscope works. I also have to explain what quantum tunneling is and how it is used in a scanning tunneling microscope. I've done some research on the internet and I think I have a basic grasp of quantum tunneling. However, I have no idea how it is applied in the scanning tunneling microscope. I would really appreciate it if someone could explain this to me. I should probably also confirm whether my understanding of quantum tunneling is correct. I'll try to explain what I know in layman's terms, since that's how I'll be presenting it. Quantum tunneling is the idea that an object, when colliding with a surface, has a very small chance of "tunneling" through the surface. For example, when throwing a tennis ball at a wall, there is a small chance that it will appear on the other side of the wall. This chance is VERY small (close to nil?) for large objects such as the tennis ball. However, for very small matter, such as electrons, quantum tunneling is realistic. Does that sound about right?