Researchers at Caltech used optical hardware to realize cellular automata, a type of computer model consisting of a “world,” or grid containing “cells” — represented by each individual square of the grid — that can live, die, reproduce, and evolve into multicellular creatures with unique behaviors. These automata, which have been used to perform computing tasks, are ideally suited to photonic technologies, according to Caltech assistant professor of electrical engineering and applied physics Alireza Marandi.
“If you compare an optical fiber with a copper cable, you can transfer information much faster with an optical fiber,” Marandi said. “The big question is, ‘Can we utilize that information capacity of light for computing as opposed to just communication?’ To address this question, we are particularly interested in thinking about unconventional computing hardware architectures that are a better fit for photonics than digital electronics.”
Technically speaking, cellular automata are computational models and can be thought of as simulated cells that follow a very basic set of rules, with each type of automata operating under its own set of rules. However, beyond these simple rules, complex behaviors can emerge in the automata. One of the best-known cellular automata, called The Game of Life or Conway’s Game of Life, was developed by English mathematician John Conway in 1970. It has just four rules that are applied to a grid of “cells” that can either be alive or dead:
- Any live cell with fewer than two live neighbors dies, as if by underpopulation.
- Any live cell with more than three live neighbors dies, as if by overcrowding.
- Any live cell with two or three live neighbors lives to the next generation.
- Any dead cell with exactly three live neighbors will come to life, as if by reproduction.
A computer running The Game of Life repeatedly applies these rules to the world in which the cells live at a regular interval, with each interval being considered a generation. Within a few generations, those simple rules lead to the cells organizing themselves into complex forms with evocative names such as loaf, beehive, toad, and heavyweight spaceship.