No, you cannot physically cut air with a knife. A knife is a tool designed to cut through solid objects, such as food, materials, or other tangible substances. Air, on the other hand, is a gaseous substance composed of molecules that are widely dispersed and not densely packed together like solids or liquids.
Since air is not a solid or a liquid, it does not provide a physical resistance that can be cut. When you try to move a knife through the air, it simply passes through without encountering any substantial resistance or being divided. The knife essentially moves through the spaces between the air molecules.
However, it's worth noting that when a knife is moved rapidly through the air, it can create airflow and possibly generate wind or a breeze due to its movement. This effect is due to the displacement and movement of the air molecules caused by the knife's motion, rather than physically cutting the air itself.