Do Atoms Ever Touch?

Atoms touch all the time! But to understand why we first have to decide what we mean by the word “touch.” Our normal conception of touching is grounded in the macroscopic world. I put a cup on the table – the cup is touching the table. You dip your toes in the water – you are touching the water, and so on. In all these cases, one solid boundary or surface (the bottom of the cup, the edge of your toe) touches another solid boundary or surface (the top of the table, the sur