Nanoscientists use powerful microscopes called scanning probe microscopes to “see” atoms and molecules. In school or maybe at home you probably used an optical microscope. With those microscopes you can see cells. Scanning probe microscopes are a lot different than optical microscopes. Instead of using lenses and light to magnify a specimen, scanning probe microscopes “see” by using a really tiny needle as a probe.

This special needle is used to “feel” the surface of a specimen and it sends back information that makes a kind of picture. So under the right conditions, you can see atoms and molecules.

Scanning probe microscopes are pretty big and are tricky to work. The really tough part is getting the atoms and molecules to stay still. Since atoms and molecules are in constant motion, the only way to do this is to keep them really cold, because the colder they are the slower they move. How cold? Almost absolute zero, five degrees Kelvin—that’s minus 450 degrees Fahrenheit. Brrr!!! The other problem is that you have to get rid of most of the atoms, which means working in a vacuum because even air has a lot of atoms.

Scientists have one way to see how molecules behave without even making them or testing them for real. They can see how molecules might self-assemble using simulations. Simulations are done on computers that can figure out all of the forces that make molecules self-assemble. Sort of like a video game where you crash the car into the wall and it bounces off, simulating what might happen for real. It looks real because the computer figures out what it should look like and simulates the movements of the crash.

Scientists use simulations to figure out how to make better molecules, including ones that self-assemble better. Simulations help scientists make predictions without going into the laboratory or using a scanning probe microscope.