The concept that matter is made up of tiny atoms has been proposed for millennia, but we rely on our five senses to provide the ultimate truth. The 1986 Nobel Prize for Physics rewarded two radical leaps in microscope technology that finally allowed us to witness life at the atomic level.
The light microscope, invented in the 17th century, provided scientists with the first extension of the human eye, but observing anything in greater detail is limited by the wavelength of light. In the same way that large ocean waves are not affected significantly by small objects, it is impossible for visible light to produce an image of objects such as proteins and atoms that are smaller than its wavelength.
The development of the electron microscope opened up this previously hidden world. The electron microscope works on the principle that a short coil carrying an electric current can deflect electrons in the same way that a lens deflects light. Ernst Ruska heard about this theory, then a daring hypothesis, when he was an engineering student in 1928. Within just five years he designed and built the first electron microscope, using two coils as magnetic lenses for electrons. As electrons have a much smaller wavelength than light, this microscope could see details many times smaller than is possible with a light microscope.
Almost 50 years later, Gerd Binnig and Heinrich Rohrer succeeded in designing the scanning tunneling microscope, in which a remarkably fine stylus scans a surface and its vertical movement is used to create a topographical map of the surface at the atomic level. Generating faithful images relies on keeping the stylus at a fixed distance from the surface, which Binning and Rohrer solved using the so-called tunneling effect, in which a current flows between the needle tip and the surface only if they are close enough together. Thanks to their advances, crystal surfaces, DNA molecules and viruses could be visualized, opening up new vistas to life around us.