An Oscillator is any pattern in the Game of Life that returns to its original state after a fixed number of generations. This cycle period is called the "period" of the oscillator.
The simplest oscillator is the Blinker (shown here). It consists of three cells in a row. It alternates between a horizontal line and a vertical line (period 2). It is the most common object in the Game of Life universe.
Oscillators come in all shapes and sizes, from the tiny Blinker to the massive Pulsar and Pentadecathlon. They are the "clocks" of the Life universe, keeping time and maintaining stable rhythms amidst the chaos.
Click "Open in Simulator" to see this pattern evolve.