 In our How Small Is It chapter on the microscopic, we covered scanning electron microscopes that mapped the surface of an object by using the wave nature of electrons and analyzing their scattering properties. Here we will cover scanning tunneling microscopes, or STM for short, that use the quantum mechanical tunneling property. Here's an STM at the Max Planck Institute. It has a small pinhead that is actually one single atom at its tip. The tip is brought close enough to the object or electrons to tunnel across the space, exactly in accordance with Schrodinger's equation. This creates an electric current. As the tip scans across the object, the current will go up or down depending on whether an atom is under the tip or not. This is repeated over and over till the entire surface is mapped. What we are doing is actually feeling the surface of the object to see and measure the atoms. With a little stronger pull, we can even dislodge and move atoms. Here we see that the scientists at the Max Planck Institute move the atoms one by one to spell their institute's initials, MPI. The tag is just six nanometers wide.