A growing revolution in imaging is making it possible for biologists to watch small-scale events as they unfold in living cells and tissues.

New technologies—more sophisticated imaging techniques, fluorescent molecules that act as beacons of light in the cell, and the computing power to gather and stitch together multiple images and create videos from high-powered microscopes—make it possible to harness one of light’s key advantages: gentleness. Unlike higher-resolution techniques, light microscopes can image biological structures without killing them or chemically fixing them. At Harvard, the resurgence of light microscopy is making it possible to see structures and events that have never before been seen in the context of living cells and organisms. New discoveries are emerging at many scales of life, from the activation of a single gene in DNA to the development of disease in an organ.