When Lightning Strikes Twice (Or Thrice)
Alexander Graham Bell and Elisha Gray filed patents for the telephone on the same day.
Welcome back to Input Origins, your monthly time machine through the evolution of how we control our devices! This month, we're exploring something fascinating, how the same input breakthrough gets invented multiple times, by different people, in different places, with zero connection to each other.
It's called Multiple Discovery. And in the world of input devices? It happens more often than you'd think. Today, we're diving into two iconic examples: the touchscreen and the trackball. Both were invented simultaneously by different inventors, working independently, solving the same problem. When a control problem is ripe enough, the solution doesn't wait for one genius to solve it. It shows up in many places at once. Pretty wild, right?
A 1960s trackball controlling Honeysuckle Creek antenna and 1981 Wico Command Control.
The Trackball - Invented Four Times Over
The trackball holds a special place in the story of Multiple Discovery, it was independently invented four times! Three times for radar, once for gaming. (We covered its full story in Input Origins #15).
It started with a problem. Radar operators needed to track moving targets on screen with precision and speed. Joysticks were too shaky. Keyboards couldn't handle fluid 2D movement.
The solution? A ball in a socket. Smooth, stationary, and precise.
In 1946, British engineer Ralph Benjamin built the "roller ball", a metal ball rolling on rubber-coated wheels that translated rotation into coordinates. Six years later in 1952, Naval engineers at Ferranti Canada, solved the same problem with their own version using a five-pin bowling ball on air bearings with digital pulse sensors. Then in 1965, engineers at Telefunken in West Germany created the "Rollkugel" for radar flight control, using the same ball-in-socket principle. Three teams. Three countries. Zero connection. Each solving the same radar targeting problem with the same elegant answer.
And then it happened a fourth time. In 1978, Atari's engineering team independently reinvented the trackball. Atari Football became the first public appearance of a trackball outside of military secrecy.
E.A. Johnson's 1965 capacitive touchscreen and the HP 150 (1983)
The Touchscreen's Identity Crisis: A Triple Origin Story
If the trackball was invented four times, the touchscreen might have it beat. The idea of touching a screen to control it emerged independently across three continents, using completely different physics, by people who had never heard of each other.
In 1965, E.A. Johnson at the UK's Royal Radar Establishment needed a faster way for air traffic controllers to interact with their screens. Keyboards and mice were too slow. His solution, a grid of transparent conductive wires over a display, activated by the electrical charge in a human finger. The capacitive touchscreen was born!
Five years later, on the other side of the Atlantic, physicist Samuel Hurst at the University of Kentucky wasn't even trying to build an input device. He was logging data coordinates and accidentally created the Elograph, a resistive touchscreen that worked by pressing two conductive layers together. A different technology, same result.
And then, around 1972, at CERN in Switzerland, Frank Beck and Bent Stumpe faced their own problem. Their particle accelerator had too many parameters and too little room for physical knobs. Their answer? Etch copper buttons onto glass, turning the display itself into the control panel. Three locked silos: Government aviation in the UK, academic physics in the US, particle research in Switzerland. No shared data. Three different approaches. One same solution, touch the screen.
Multiple Discovery Explained
Multiple discovery isn't unique to input devices! It shows up everywhere. Newton and Leibniz both invented calculus around 1684. Darwin and Wallace arrived at evolution by natural selection independently, almost simultaneously. Bell and Elisha Gray filed patents for the telephone on the same day. It happens in movies too, "The Illusionist" and "The Prestige" two films about 19th century magicians released in the same week in 2006, as well as two Fyre Festival documentaries released in the same week in 2019. And it even happens in nature itself, wings evolved independently in birds, bats, and insects. Echolocation emerged separately in bats and dolphins.
So what's going on? One theory suggests that discoveries aren't really about lone geniuses at all. Knowledge accumulates gradually, like letters filling in on a board, until the answer becomes almost inevitable. The people matter less than the conditions. When the problem is ripe and the building blocks are available, the solution surfaces, sometimes in multiple places at once.
And that's exactly what we see in input. When radar operators needed precision, the trackball appeared three times. When screens needed touch, three unconnected teams built it using different physics. The pattern keeps repeating.
Which raises an interesting question, what's emerging right now, in multiple places at once?
