When David G. Grier got a tenure-track teaching position at the University of Chicago in 1992, he expected to continue the work on high-temperature superconductors that he had completed as a postdoctoral fellow at Bell Labs. Biding his time while his superconductor laboratory was being set up, he decided to carry out what he thought would be a quick and easy experiment on suspensions of particles, called colloids. These materials serve as a means for scientists to study how the atoms in metal crystals or other collections of tiny particles interact with one another, without having to move around individual atoms.

"We whipped up the experiment, and nothing was what it was supposed to be," Grier says. One-micron-diameter latex beads carrying a negative electrical charge had demonstrated a strong attraction when they were placed in a solution of water between two closely spaced parallel plates also bearing a negative charge. "It contradicted a 50-year-old theory that holds that like charges in a solution repel," he adds. The technology needed to understand the colloids was one that he had learned to use at Bell Labs, where it had been invented.

This article was originally published with the title Hands of Light.

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