There are wave behaviors you are so used to, you don’t even think about them.  The fact that sound bends as it passes through an opening is a common enough occurrence that you probably don’t stop to think about it.  If someone is in a room and you are out in the hallway, you don’t have to be right in front of the door to hear what they are saying.  The sound bends as it passes through the doorway in a wave behavior known as diffraction.  But if that same person were to sign a flashlight at the door, the light wouldn’t bend and illuminate where you are.  As we will see next semester, light is also a wave, but the differences between light waves and sound waves mean that we will need a different experiment to see the diffraction of light.  Though passing through a doorway or around a tree is sufficient for sound to bend as it travels, we will need to rescale our doorway and our tree to see light diffract.