Touchscreen

Before touchscreens, humans communicated with computers through proxies: keyboards translated keystrokes into commands, mice translated hand movements into cursor positions. The idea of touching the display directly seemed obvious in hindsight—infants reach for objects before they can speak—but required solving a complex engineering problem: how does a screen know where a finger is?

Multiple approaches emerged independently. In 1965, E.A. Johnson at the Royal Radar Establishment in the UK described a capacitive touchscreen for air traffic control—the human finger's electrical properties would change the capacitance at the touch point. Resistive touchscreens, invented by George Samuel Hurst in 1971, used two conductive layers that made contact when pressed. At CERN in 1973, Frank Beck and Bent Stumpe built a capacitive touchscreen for the Super Proton Synchrotron control room, solving the problem of operators needing to interact with many different display configurations without constantly reaching for separate controls.

This convergent emergence across air traffic control, particle physics, and laboratory instrumentation revealed that the adjacent possible had matured. CRT displays were ubiquitous and well-understood. Transparent conductive materials (initially metal grids, later indium tin oxide) allowed electrical sensing while maintaining visibility. Analog-to-digital converters could process the continuous touch signal fast enough for responsive feedback. The core insight was recognizing that display and input could be unified.

Early touchscreens were expensive and limited to specialized applications. HP introduced touch-enabled computers in 1983. Point-of-sale terminals adopted resistive touchscreens in the 1990s because they could be operated with gloves and cleaned easily. But consumer electronics remained keyboard-and-button dominated. The transformation came when capacitive touchscreen technology matured enough for projected capacitive designs—where the sensing grid sat behind protective glass—enabling the thin, durable, multi-touch displays that would define the smartphone era.

Apple's 2007 iPhone demonstrated that capacitive multi-touch could replace nearly all physical buttons, creating an infinitely reconfigurable interface. The adjacent possible for smartphones had required not just touchscreens but ARM processors, lithium-ion batteries, MEMS sensors, and 3G networks—but the touchscreen was the visible manifestation of the transformation. By 2025, touchscreens had colonized nearly every consumer electronic device, from refrigerators to automobiles, fundamentally changing human expectations about how machines should respond to human intent.