Galilean Relativity

Galilean invariance or Galilean associatively states which the laws of motion are the similar within all inertial frames. Galileo Galilei first define this principle in 1632 in his Dialogue Concerning the Two Chief World Systems using the example of a ship travelling at constant velocity, without rocking, on a smooth sea; any observer doing experiments below the deck would not be able to tell whether the ship was moving or stationary. The fact in which the Earth orbits around the sun at around 30 km•s-1 offers a somewhat more dramatic instance, though it is technically not an inertial reference frame.