the silence after "any questions?"

Every workshop has the same moment. The material is finished. The slides go dark. You ask if there are any questions, and the room does the thing rooms do. It looks somewhere else. At the table. At a laptop. At absolutely nothing, with the intense concentration of someone studying a very important nothing.

For years I assumed this meant the material had landed cleanly. No confusion, no questions, job done. I have since revised that theory considerably, mostly because I have also sat in that exact silence, on the other side, doing the exact same thing, once while the presenter was looking directly at me.