A photon is a spaceship moving at the speed of light. Photons are not possible in Conway's Game of Life, but they do exist in other Life-like rules, for example Seeds or Live Free or Die.
x = 2, y = 4, rule = B2/S
#C [[ THUMBSIZE 2 THEME 6 GRID GRIDMAJOR 0 SUPPRESS THUMBLAUNCH ]]
#C [[ THEME 6 GRID GRIDMAJOR 0 THUMBLAUNCH AUTOSTART GPS 4 THUMBSIZE 2 TRACKLOOP 1 -1 0 ]]