Quantum reflection

Quantum reflection is a very cool trick that happens when tiny particles, like atoms or electrons, get close to a flat surface. Imagine that you are standing in front of a big wall. If you try to walk straight into the wall, you'll bump right into it and stop moving. But when tiny particles get close to a flat surface, something different happens. Instead of just stopping, they might actually turn around and start going the other way!

This happens because of something called the "wave-particle duality." Even though tiny particles are really small, they are actually made up of waves. When these waves get close to a flat surface, they can combine with other waves and create a new wave pattern that reflects the particles back, like a mirror. This can happen even if the particles have a lot of energy and should be able to overcome the barrier of the wall.

So basically, when tiny particles get close to a flat surface, they can reflect off of it like bouncing balls. This is called quantum reflection, and it's a super weird but super cool phenomenon that scientists are still studying and trying to understand better.