Modern computers can handle a grid thousands of squares across, and calculate several turns a second. We can just set up an initial pattern of squares to be alive, then sit back and watch what happens turn by turn. When you first start playing The Game Of Life, what happens is pretty unsurprising. Some patterns expand to fill large areas of the universe, then settle down into clusters of steady patterns. After playing the game for a while, Conway discovered an interesting pattern of five cells which he named a glider.
Gliders are a stable repeating cell pattern.
That is, the arrangement of living cells changes from turn to turn, but they keep returning to their original pattern after four ticks of the clock. Each time the cells return to that initial arrangement, the pattern has moved one square diagonally on the grid. The glider is, if you like, a stable moving multicellular entity within the Life universe. The challenge was printed in the pages of Scientific American magazine, and soon an MIT student named R. William Gosper, Jr had come up with a design for a glider gun. It fired out a new glider every thirty turns, proving that it was possible for a single group of living cells to expand without limit into the Life universe.