Gerd Binnig

Gerd Karl Binnig was born in Frankfurt am Main on July 20, 1947, two years after the war ended, and spent his earliest years playing in the rubble of a bombed-out city. His family lived partly in Frankfurt and partly in nearby Offenbach. At the age of ten he announced, with the certainty children sometimes muster, that he would be a physicist. The conviction wavered. For a while he poured himself into music instead, joined a band, took up the violin at fifteen, and played in his school orchestra. The two loves never quite settled their account: even decades later, after the Nobel, he would describe physics and music as the same activity in different keys.

He studied at the Goethe University in Frankfurt, finishing a bachelor’s degree in 1973 and staying on for a doctorate in Werner Martienssen’s group under Eckhardt Hoenig. His 1978 thesis on superconductivity was solid, careful work, but nothing in it signaled what was coming. That same year he accepted an offer that almost everyone in his cohort considered eccentric. Instead of a university postdoc, he joined IBM’s research lab in Rüschlikon, just outside Zürich. Industrial labs were, in 1978, where ambitious young physicists went to disappear. Binnig was about to disappear into the most important microscope of the late twentieth century.

In 1978, Binnig accepted an offer from IBM to join their Zurich research group, where he worked with Heinrich Rohrer, Christoph Gerber and Edmund Weibel. There they developed the scanning tunneling microscope (STM), an instrument for imaging surfaces at the atomic level. The Nobel committee described the effect that the invention of the STM had on science, saying that "entirely new fields are opening up for the study of the structure of matter."…

At IBM Zürich he was paired with Heinrich Rohrer, a Swiss experimentalist twenty-one years his senior, along with Christoph Gerber and Edmund Weibel. Rohrer had been thinking about a problem nobody quite knew how to solve: how to image a surface, atom by atom, without destroying it. Conventional electron microscopes blasted samples with high-energy electrons, which worked at the nanometer scale but smeared out as soon as you tried to resolve individual atoms. What if, Rohrer wondered, you used quantum tunneling instead? Bring a fine metal tip close to a conducting surface, apply a tiny voltage, and a current of electrons would tunnel across the vacuum gap. Move the tip a single atom’s diameter closer and the current jumped by a factor of ten.

The physics of tunneling had been worked out by George Gamow in the late 1920s. What nobody had managed was the engineering. To resolve a single atom you needed to hold a tip steady within a fraction of an angstrom, isolate the whole apparatus from every vibration in the building, and keep the tip itself atomically sharp. Binnig and Rohrer spent three years on the problem. Their 1981 prototype sat on a heavy stone slab floated on inflated rubber tires to damp vibrations. The lab was on the ground floor of the IBM building, and at night, when the trucks stopped rumbling outside, they could finally see atoms.

The image they produced was of a clean gold surface. Individual atoms appeared as bumps in their hexagonal lattice, exactly where theory said they should be. It was the first time a human being had ever seen an atom directly. Not inferred its presence from a scattering pattern. Seen it, in the same elemental sense one sees a marble. The first conference talk in 1982 was met with polite confusion. Within two years the same audiences were lining up to build their own scanning tunneling microscopes.

In 1986, Binnig and Rohrer shared half the Nobel Prize in Physics for the invention of the STM. The other half went to Ernst Ruska, who had built the first electron microscope more than fifty years earlier and had been waiting, with quiet patience, for recognition to arrive. The ceremony brought together three generations of microscopy: Ruska, the careful experimentalist Rohrer, and Binnig, then thirty-nine, the youngest by a wide margin.

He did not stop. The STM had a limitation that bothered him: it only worked on conducting samples. Insulators, the materials that make up most of biology, could not pass a tunneling current. In 1985, with Christoph Gerber and Calvin Quate at Stanford, he proposed a different principle. Instead of measuring tunneling current, hang the tip on a tiny flexible cantilever and measure the deflection caused by the force between tip and surface. The atomic force microscope, or AFM, was born. Unlike the STM it worked on anything: glass, plastic, DNA, living cells. Today there are more AFMs in the world than STMs by a factor of ten, and they sit in nearly every materials laboratory and semiconductor fab.

Binnig spent the second half of the 1980s shuttling between Zürich and California, based at IBM’s Almaden Research Center and visiting Stanford. In 1987 he was made an IBM Fellow and started a new IBM group in Munich, partly for AFM development and partly because he had become fascinated by what he called creativity research. He wrote a book about it, Aus dem Nichts, “Out of Nothing,” arguing that creativity follows the same branching, self-similar logic as evolution. In 1994 he founded Definiens, a company applying image-analysis ideas drawn from AFM data processing to medical imaging. In 2016, three decades after the Nobel, he received the Kavli Prize in Nanoscience for the field he had effectively founded. The Binnig and Rohrer Nanotechnology Center, IBM’s flagship research building in Rüschlikon, opened in 2011 and is named after the two men who, on a quiet night in 1981, looked at a screen and saw a row of atoms.

For the quantum story Binnig matters because he is the one who turned the wavefunction into something one can point at. Schrödinger gave us the equation. Born gave us the probabilistic interpretation. Bohr and Heisenberg gave us the uncertainty principle. But it was Binnig and Rohrer who built the instrument that let us watch a single atom, in real space, on a screen. Quantum mechanics stopped being inferential the night the first STM image came up. Whatever the wavefunction is, we now know where it lives.