But how far are we from the theoretical bottom?
Just about another factor of a thousand, it turns out.
If we shrink from a micrometre to a thousandth of that, a nanometre, we've reached the scale where atoms become tangible objects. A one nanometre cube of diamond has 176 atoms in it.
Designing at this scale is working in a world where physics, chemistry, electrical engineering, and mechanical engineering become unified into an integrated field.
This field will be called molecular engineering, and I believe it will be at the heart of the next two industrial revolutions.