"I couldn't stop looking at the images," Gerd Binnig would say later, when accepting the Nobel Prize in 1986. "It was entering a new world."
Just four years before, in 1982, he and Heinrich Rohrer had invented a microscope that could probe a piece of material, inspect the atoms that made it up, and report back. But there was more; not only could they inspect the atoms—they could move them, too.
For centuries, scientists had been using light and lenses to see beyond the resolutions allowed by the inborn lenses of the human eye. But only since the 1930s had they been able to observe the world at scales smaller than light can elucidate.
In 1933, a German physicist had developed an electron microscope that could create images at a smaller scale than the best light microscope at the time—by sending electrons, rather than waves of light, through a sample. And as these so-called "transmission electron microscopes" improved, they showed with increasingly clarity the world of small things.
Just a few years later, another German inventor created a scanning electron microscope that would show the depth and surface features of the sample.
The microscope that Binnig and Rohrer created did something different. It held a teeny probe, its point as small as a single atom, near the surface of a sample. The probe obtains its information from electrons "tunneling"—coasting on their quantum wave properties—through the material, and uses that information to create an image of its surface at the atomic level.
This, essentially, is why nanotechnology research has sped up so quickly in the past decades. These probes can not only see on these atomic levels, but they can reach out and touch the atoms, moving them into place. Here's one way to think about it, from Julian Chen's Introduction to Scanning Tunneling Microscopy:
It was often said that STM is to nanotechnology what the telescope was to astronomy. Yet STM is capable of manipulating the objects it observes, to build nanoscale structures never existed in Nature. No telescope is capable of bringing Mars and Venus together.